organic chemistry – Page 3

Improving Drug Delivery Chemotherapy: Light activation improves penetration and efficacy of nanoparticles as carriers

drugs, GENERIC Comments Off

Nov 132013

A schematic showing how chemotherapy-carrying nanoparticles (left) penetrate deeper into tumor sites and decompress blood vessels after the tumors are irradiated with ultraviolet light (right).

Nanoparticles carrying a cancer drug are administered to mice and exposed to UV light, causing them to contract and release the drug into tumors.

Credit: Modified from Proc. Natl. Acad. Sci. US

http://cen.acs.org/articles/91/i45/Improving-Drug-Delivery.html

Nanoparticles are promising cargo ships for targeted drug delivery. But the materials have had limited success treating cancer, because they often can’t penetrate deep into tumors. The nanoparticles are stalled by the extracelluar matrix and compressed blood vessels.

http://cen.acs.org/articles/91/i45/Improving-Drug-Delivery.html

TAMOXIFEN, can treat and prevent one type of breast cancer, without the side effects of chemotherapy.

GENERIC, PROCESS, Uncategorized Comments Off

Nov 082013

TAMOXIFEN

10540-29-1 CAS

READ ABOUT TITLE AT……….http://www.rsc.org/chemistryworld/sites/default/files/CIIE_Tamoxifen.mp3

Molecular Formula: C₂₆H₂₉NO•C₆H₈O₇
CAS Number: 54965-24-1
Brands: Nolvadex, TAMOXIFEN CITRATE

Chemically, NOLVADEX (tamoxifen citrate) is the trans-isomer of a triphenylethylene derivative. The chemical name is (Z)2-[4-(1,2-diphenyl-1-butenyl) phenoxy]-N, N-dimethylethanamine 2 hydroxy-1,2,3- propanetricarboxylate (1:1). The structural and empirical formulas are:

NOLVADEX (Tamoxifen Citrate) Structural Formula Illustration

Tamoxifen citrate has a molecular weight of 563.62, the pKa’ is 8.85, the equilibrium solubility in water at 37°C is 0.5 mg/mL and in 0.02 N HCl at 37°C, it is 0.2 mg/mL.

NDA021807 APPR2005-10-29 DARA BIOSCIENCES,

SOLTAMOX

US PATENT 6,127,425

US 6127425

APPROVED 1998-06-26

EXPIRY 2018-06-26

Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist, and thus may be characterized as a mixed agonist/antagonist. Tamoxifen is the usual endocrine (anti-estrogen) therapy for hormone receptor-positive breast cancer in pre-menopausal women, and is also a standard in post-menopausal women although aromatase inhibitors are also frequently used in that setting.

Some breast cancer cells require estrogen to grow. Estrogen binds to and activates the estrogen receptor in these cells. Tamoxifen is metabolized into compounds that also bind to the estrogen receptor but do not activate it. Because of this competitive antagonism, tamoxifen acts like a key broken off in the lock that prevents any other key from being inserted, preventing estrogen from binding to its receptor. Hence breast cancer cell growth is blocked.

Tamoxifen was discovered by pharmaceutical company Imperial Chemical Industries (now AstraZeneca) and is sold under the trade names Nolvadex, Istubal, and Valodex. However, the drug, even before its patent expiration, was and still is widely referred to by its generic name “tamoxifen.

Breast cancer

Tamoxifen is currently used for the treatment of both early and advanced ER+ (estrogen receptor positive) breast cancer in pre- and post-menopausal women.Additionally, it is the most common hormone treatment for male breast cancer. It is also approved by the FDA for the prevention of breast cancer in women at high risk of developing the disease. It has been further approved for the reduction of contralateral (in the opposite breast) cancer.

In 2006, the large STAR clinical study concluded that raloxifene is equally effective in reducing the incidence of breast cancer, but after an average 4-year follow-up there were 36% fewer uterine cancers and 29% fewer blood clots in women taking raloxifene than in women taking tamoxifen, although the difference is not statistically significant.

Nolvadex (tamoxifen) 20 mg tablets

In 2005, the ATAC trial showed that after average 68 months following a 5 year adjuvant treatment, the group that received anastrozole (Arimidex) had significantly better results than the tamoxifen group in measures like disease free survival, but no overall mortality benefit. Data from the trial suggest that anastrozole should be the preferred medication for postmenopausal women with localized breast cancer that is estrogen receptor (ER) positive.Another study found that the risk of recurrence was reduced 40% (with some risk of bone fracture) and that ER negative patients also benefited from switching to anastrozole.

Crystallographic structure of 4-hydroxy-tamoxifen (carbon = white, oxygen = red, nitrogen = blue) complexed with ligand binding domain of estrogen receptor alpha (cyan ribbon)

Tamoxifen

lTamoxifen was first developed in 1962 as a morning-after birth control pill that was successful in experiments with laboratory rats.

lTamoxifen (brand name Nolvadex) is the best-known hormonal treatment and the most prescribed anti-cancer drug in the world.

lUsed for over 20 years to treat women with advanced breast cancer, tamoxifen also is commonly prescribed to prevent recurrences among women with early breast cancer.

lIs a SERMs.

Anti-estrogens work by binding to estrogen receptors, blocking estrogen from binding to these receptors, stopping cell proliferation

lBreast-cancer prevention occurred in 1998 when the National Cancer Institute (NCI) announced results of a six-year study showing that tamoxifen reduced the incidence of breast cancer by 45 percent among healthy but high-risk women.

l13,388 healthy women considered at high risk for breast cancer were recruited

l85 developed breast cancer compared to 154 of those on the placebo or dummy pill.

lpotentially life-threatening side effects. There were 33 cases of endometrial cancer in the tamoxifen group

lThere were 30 cases of blood clots in major veins (deep-vein thrombosis)

lBecause these problems developed exclusively among postmenopausal women

–60-year-old, an age at which 17 out of every 1,000 women can be expected to develop breast cancer within five years

–ages of 35 and 59 were eligible to participate if their risks matched or exceeded those of a 60-year-old

lAlthough tamoxifen has been useful both in treating breast cancer patients and in decreasing the risk of getting breast cancer.

lSide effects arise from the fact that while tamoxifen acts as an antiestrogen that blocks the effects of estrogen on breast cells, it mimics the actions of estrogen in other tissues such as the uterus. Its estrogen-like effects on the uterus stimulate proliferation of the uterine endometrium and increase the risk of uterine cancer.

Adequate patent protection is required to develop an innovation in a timely manner. In 1962, ICI Pharmaceuticals Division filed a broad patent in the United Kingdom (UK) (Application number GB19620034989 19620913). The application stated, “The alkene derivatives of the invention are useful for the modification of the endocrine status in man and animals and they may be useful for the control of hormone-dependent tumours or for the management of the sexual cycle and aberrations thereof. They also have useful hypocholesterolaemic activity”.

This was published in 1965 as UK Patent GB1013907, which described the innovation that different geometric isomers of substituted triphenylethylenes had either oestrogenic or anti-oestrogenic properties. Indeed, this observation was significant, because when scientists at Merrell subsequently described the biological activity of the separated isomers of their drug clomiphene, they inadvertently reversed the naming. This was subsequently rectified.

Although tamoxifen was approved for the treatment of advanced breast cancer in post-menopausal women in 1977 in the United States (the year before ICI Pharmaceuticals Division received the Queen’s Award for Technological Achievement in the UK), the patent situation was unclear. ICI Pharmaceuticals Division was repeatedly denied patent protection in the US until the 1980s because of the perceived primacy of the earlier Merrell patents and because no advance (that is, a safer, more specific drug) was recognized by the patent office in the United States. In other words, the clinical development advanced steadily for more than a decade in the United States without the assurance of exclusivity. This situation also illustrates how unlikely the usefulness of tamoxifen was considered to be by the medical advisors to the pharmaceutical industry in general. Remarkably, when tamoxifen was hailed as the adjuvant endocrine treatment of choice for breast cancer by the National Cancer Institute in 1984, the patent application, initially denied in 1984, was awarded through the court of appeals in 1985. This was granted with precedence to the patent dating back to 1965! So, at a time when world-wide patent protection was being lost, the patent protecting tamoxifen started a 17 year life in the United States. The unique and unusual legal situation did not go uncontested by generic companies, but AstraZeneca (as the ICI Pharmaceuticals Division is now called) rightly retained patent protection for their pioneering product, most notably, from the Smalkin Decision in Baltimore, 1996. (Zeneca, Ltd. vs. Novopharm, Ltd. Civil Action No S95-163 United States District Court, D. Maryland, Northern Division, March 14, 1996.)

Title: Tamoxifen

CAS Registry Number: 10540-29-1

CAS Name: (Z)-2-[4-(1,2-Diphenyl-1-butenyl)phenoxy]-N,N-dimethylethanamine

Additional Names: 1-p-b-dimethylaminoethoxyphenyl-trans-1,2-diphenylbut-1-ene

Molecular Formula: C26H29NO

Molecular Weight: 371.51

Percent Composition: C 84.06%, H 7.87%, N 3.77%, O 4.31%

Literature References: Nonsteroidal estrogen antagonist.

Prepn: BE 637389 (1964 to ICI). Identification and separation of isomers: G. R. Bedford, D. N. Richardson, Nature 212, 733 (1966); BE 678807; M. J. K. Harper et al., US 4536516 (1966, 1985 both to ICI). Stereospecific synthesis: R. B. Miller, M. I. Al-Hassan, J. Org. Chem. 50, 2121 (1985). Review of chemistry and pharmacology: B. J. A. Furr, V. C. Jordan, Pharmacol. Ther. 25, 127-205 (1984). Reviews of clinical experience in treatment and prevention of breast cancer: I. A. Jaiyesimi et al., J. Clin. Oncol. 13, 513-529 (1995); C. K. Osborne, N. Engl. J. Med. 339, 1609-1618 (1998).

Properties: Crystals from petr ether, mp 96-98°.

Melting point: mp 96-98°

Derivative Type: Citrate

CAS Registry Number: 54965-24-1

Manufacturers’ Codes: ICI-46474

Trademarks: Kessar (Pharmacia); Nolvadex (AstraZeneca); Tamofène (Aventis); Zemide (Alpharma); Zitazonium (Servier)

Molecular Formula: C26H29NO.C6H8O7

Molecular Weight: 563.64

Percent Composition: C 68.19%, H 6.62%, N 2.49%, O 22.71%

Properties: Fine, white, odorless crystalline powder, mp 140-142°. Slightly sol in water; sol in ethanol, methanol, acetone. Hygroscopic at high relative humidities. Sensitive to uv light. LD50 in mice, rats (mg/kg): 200, 600 i.p.; 62.5, 62.5 i.v.; 3000-6000, 1200-2500 orally (Furr, Jordan).

Melting point: mp 140-142°

Toxicity data: LD50 in mice, rats (mg/kg): 200, 600 i.p.; 62.5, 62.5 i.v.; 3000-6000, 1200-2500 orally (Furr, Jordan)

Derivative Type: (E)-Form

CAS Registry Number: 13002-65-8

Properties: mp 72-74° from methanol.

Melting point: mp 72-74° from methanol

Derivative Type: (E)-Form citrate

Manufacturers’ Codes: ICI-47699

Properties: mp 126-128°.

Melting point: mp 126-128°

CAUTION: Tamoxifen is listed as a known human carcinogen: Report on Carcinogens, Eleventh Edition (PB2005-104914, 2004) p III-239.

Therap-Cat: Antineoplastic (hormonal).

Keywords: Antineoplastic (Hormonal); Antiestrogens; Selective Estrogen Receptor Modulator (SERM).

Synthesis of the E and Z isomers of the antiestrogen Tamoxifen. David W.Robertson and John A. Katzenellenbogen. Journal of Organic Chemistry 1982 , 47, Pages 2387-2393. An early synthesis of Tamoxifen : Production of non stereo specific products.

For easy of understanding the complete synthesis has been broken down into a number of steps.Step 1.

Step 1. This step shows use of a simple friedel-craft acylation involving Anisole(A) and Phenylacetic acid (B). The acylating agent in this process was a mixture of PCl5 / SnCl4. The ketone C was formed in a 78% yield.

Step 2.

Step 2.

Alkylation was promoted by treating the ketone C with Sodium hydride (NaH). This removed the acidic protons (located on the position alpha to the carbonyl group) to produce the enolate ion. This could be isolated as the sodium enolate of the ketone treatment of this with ethyl iodide resulted in the formation of compound (D) in a 94% yield. The Ethyl iodide was chosen as the acylating agent probably as it contains the iodide ion , which is an excellent leaving group. It can therefore facilitate an SN2 substitution reaction with relative easy.

Step 3.

Step 3. The phenol was deprotected using Lithium ethanthiolate in DMF ( Dimethyl This facilitated the removal of the methyl group and replaced it with a H to form a hydroxl group. Thus forming compound (E) in a 96% yield.

This is a key step as it has left a chink in the armour of the molecule. This can then be used to build up a characteristic part of the Tamoxifen molecule. (eg the (diemthylamino)ethyl group can be added easily from here)

Step 4.

Step 4.

Then product E can be alkylated by treatment with 2-(dimethylamino) ethy chloride. The most facile site of alklation is the OH group on the phenyl ring. This can be interpreted roughly by using HSAB theory. e.g Hard and Soft acid/base theory. The carbon adjacent to the chloride ion of the reactant 2-(dimethylamino)ethyl chloride is made slightly harder due to the process of symbiosis. This can rationalise the formation between the hard oxygen atom to the normally soft carbon atom. In this case the carbon atom has become slightly harder due to the presence of the hard chorine atom. Hence the interaction is favourable by HSAB theory. The above reaction gives product F via a SN2 substitution reaction in 70% yield.

Step 5.

Step5.

F on treatment with PhMgBr forms the tertiary alcohol (G).

Formation of the Grignard reagent can be achieved via reaction of PhBr + Mg —–> PhMgBr. The Grignard reagent has effectively formed a carbanion species eg C delta negative (-ve). This is due to the presence of the C-Mg bond. the fact that Magnesium is a more electropositive element thus making the Carbon atom the more electronegative element and hence acquiring a negative charge. As a result of the negative nature of the carbon atom it can now attack the delta positive (+ve) Carbon atom of the carbonyl group.

step 6.

Step 6.The dehydration of F was initiated by treatment of methanoic hydrogen chloride. this gives the required structure of Tamoxifen. However it gives a racemic mixture of both cis and trans isomers.

The ratio of the Cis / Trans isomers was (1.3 / 1). These isomers of Tamoxifen can be separated by Silica gel thin layer chromatography with benzene / triethylamine (9:1) as the developing solvent. Analysis of this technique revealed that the Z (Trans) isomer was more mobile than the E (Cis) isomer.

Synthetic Route 2: A Stereospecific Approach.

Stereospecific Synthesis of (Z) – Tamoxifen via carbometalation of Alkynylsilanes.

Studied for historical reasons rather than synthetic brilliance. This synthesis was the first stereo specific synthesis of (Z) Trans Tamoxifen. Comparison between this synthesis and the previous route I believe can illustrate the development of synthetic approaches to large molecules. In particular the quest for stereo specific reactions. So starting from an alkynylsilane (A) and through a series of reactions we can generate only the (Z) – Trans isomer of Tamoxifen.

Again for ease of understanding the complete synthesis has been broken down into a number of steps.

Step1.

Step1.

This step contains the vital stereo specific step. Namely the carbometalation of the alkynylsilane.It is this step which establishes the stereochemistry about the double bond. The phenyl (trimethyl silyl) – acetylene was carbometalated with diethylaluminium chloride – titanocene dichloride reactant to produce an organometallic intermediate. This organometallic intermediate was then cleaved with N bromosucciniamide to produce the alkene (B) in 85% yield.

The stereochemistry was assigned as E (Cis) mechanistic evidence suggests that this is linked to some steric reasons.

(Earlier work dedicated to this reaction see : Miller, R.B. Al-Hassan.M.I J.Org.Chem. 1984, 49, 725)

Step2.

Step 2.

The second step shows the stereo specific replacement of the Br group by a phenyl group. This was achieved by use of Palladium – catalysed coupling of compound (B) with phenyl zinc chloride to form (C) the vinylsilane in a 95% yield.

Step3.

Step3.

This step during the synthesis was reported to be tricky and several approaches were attempted before a successful technique was discovered.

The objective of this step was to replace the trimethyl Silyl group by a suitable halogen atom (e.g. Bromine or Iodine)

However a facile reaction was reported when (C) was treated with bromine – sodium methoxide at -78�C to produce the vinyl bromide (D) in a yield of 85%

Step 4.

Step 4.

The vinyl bromide (D) coupled well with a Zinc organometallic species to produce (E) the ethyl triaryl olefin in a yield of 84%.

Step 5.

The formation of (F) Tamoxifen was achieved by demethylation with sodium ethylthoilate in refluxing dimethyl formamide. then reaction of the phenoxide ion with 2-( dimethylamino)ethyl chloride via a SN2 substitution.

Purification of the crude product was achieved via it’s hydrochloride salt ( via a reaction with HCl (g)) then F was regenerated by treatment with dilute base this produced the stereospecific (Z)- Trans isomer in an overall yield of 60%.

a synthesis

Palladium-Catalyzed Fluoride-Free Cross-Coupling of Intramolecularly ActivatedAlkenylsilanes and Alkenylgermanes: Synthesis of Tamoxifen as a Synthetic Application (pages 642–650)Kenji Matsumoto and Mitsuru ShindoArticle first published online: 23 FEB 2012 | DOI: 10.1002/adsc.201100627

http://pubs.rsc.org/en/content/articlelanding/2011/cs/c0cs00129e#!divAbstract

EP 0883587 A1 WO1997026234A1)

Preparation of Z isomer of Tamoxifen

A solution of bromobenzene (3.92g, 25mmol) in ether (5ml) containing a crystal of iodine was added dropwise to a suspension of magnesium turnings (0.63g, 26mmol) in ether (5ml) at reflux, under nitrogen. After the addition was complete, the reaction mixture was cooled to room temperature and a solution of l- [ 4- ( 2- chloroethoxy)phenyl]-2-phenyl-l-butanone (3.75g, 12.4mmol) in ether (15ml) was added over 1 hour. The resulting mixture was refluxed for 16 hours, then poured into dilute hydrochloric acid (50ml) and extracted with ether (3x40ml) . The combined ether layers were concentrated, the residual oil was dissolved in ethanol (10ml) and refluxed with concentrated hydrochloric acid (5ml) for 4 hours. The organic phase was separated, dried (Na₂S0₄) and evaporated to dryness to give a yellow oil. Η NMR (see Figures 1 to 4 and discussion below) showed this to be a 2:1 mixture of the Z and E isomers. The oil was then dissolved in warm methanol (about 40°C) and allowed to cool to room temperature. The colourless crystals formed proved to be pure Z isomer of 2-chloroethoxy tamoxifen (4.12g, 11.4mmol, 92% yield) . M.p. 107-109°C, m/z 362/364 (chlorine atom present), <S_H 0.92 (3H, t, J = 7.33 Hz, CH₃) , 2.46 (2H, q, J = 7.33 Hz, CH₂CH₃) , 3.72 (2H, t, J = 5.86 Hz, 0CH₂CH₂C1) , 4.09 (2H, t, J = 5.86 Hz, 0CH₂CH₂C1) , 6.55 (2H, d, J = 8.79 Hz, aromatic protons ortho to 0CH₂CH₂C1) , 6.79 (2H, d, J = 8.79 Hz, aromatic protons meta to 0CH₂CH₂C1) , 7.10-7.38 (10H, m, the two remaining C₆H₅ ^,s) (see Figure 5) . The 2-chloroethoxy tamoxifen was reacted with dimethylamine in ethanol, under reflux, to produce the desired Z isomer of tamoxifen.

Analysis of Η NMR data

Figures 1 to 4 represent a mixture of the E- and Z- forms of compound XI described above.

The expansion of the region ό^* 0.80 to 1.05 shows two overlapping triplets corresponding to the CH₃ groups in the

Z- and E- derivatives respectively. The critical point is the ratio of the heights of the peaks at 0.92 (for the Z) and 0.94 (for the E) , which is approximately 2:1. The expansion of the 4.00 to 4.35 region reveals similar information where ratios are 10:6.4 and 5.56:3.43.

Similarly expansion of the region 3.6 to 3.9 shows the ratio to be 2.46:1. All of these measurements suggest an approximate 2:1 ratio.

Referring to Figure 5, this shows almost pure Z- isomer. It should be noted that there is 660 mg of this from an original mixture of a 2:1 ratio mixture of 780 mg which would contain only 520 mg of the Z-isomer.

Z isomer of tamoxifen and 4-hydroxytamoxi en include stereoselective syntheses (involving expensive catalysts) as described in J. Chem. Soc, Perkin Trans I 1987, 1101 and J. Org. Chem. 1990, 55, 6184 or chromatographic separation of an E/Z mixture of isomers as described in J. Chem. Res., 1985 (S) 116, (M) 1342, 1986 (S) 58, (M) 771.

(Z)-tamoxifen (1) as a white solid, mp: 95.8-96.3 ºC. ¹H-NMR (500 MHz, CDCl₃) d 0.92 (3H, t, J 7.3 Hz), 2.29 (6H, s), 2.45 (2H, q, J 7.3 Hz), 2.65 (2H, t, J 5.8 Hz), 3.93 (2H, t, J 5.8 Hz), 6.68 (2H, d, J 9.5 Hz), 6.78 (2H, d, J 9.5 Hz), 7.08-7.28 (10H, m).¹³C-NMR (125 MHz, CDCl₃) d 13.6 (CH₃), 29.0 (CH₂), 45.8 (CH₃), 58.2 (CH₂), 65.5 (CH₂), 113.4 (C), 126.0 (C), 126.5 (CH), 127.8 (CH), 128.1 (C), 129.7 (C), 131.8 (CH), 135.6 (CH), 138.2 (CH), 141.3 (CH), 142.4 (CH), 143.8 (C), 156.7 (C). IR (KBr film) n_max/cm^-1: 3055, 2979, 2925, 2813, 2769, 1606, 1509, 1240, 1035, 707. GC–MS (EI) m/z 371(5%), 58(100%).

(Z)-tamoxifen (1) and (E)-tamoxifen (2) in 52% yield. ¹H-NMR (300 MHz, CDCl₃) d 0.91 (Z isomer. 3H, t, J 7.3 Hz), 0.94 (E isomer. 3H, t, J 7.3 Hz), 2.28 (Z isomer. 6H, s), 2.34 (E isomer. 6H, s), 2.42-2.52 (Z and Eisomers. 4H, m), 2.63 (Z isomer. 2H, t, J 5.9 Hz), 2.74 (E isomer. 2H, t, J 5.9 Hz), 3.94 (Z isomer. 2H, t, J 5.9 Hz), 4.07 (E isomer. 2H, t, J 5.9 Hz), 6.68 (Z isomer. 2H, d, J 9.7 Hz), 6.76 (E isomer. 2H, d, J 9.3 Hz), 6.86-7.36 (Z and E isomers. 10H, m). IR (KBr film) n_max/cm^-1: 3081, 3056, 2974, 2826, 2770, 1611, 1509, 1238, 1044. GC–MS (EI) m/z: Z isomer, 371(4%), 72 (24%), 58(100%); E isomer, 371(3%), 72 (24%), 58(100%). (the diastereoisomeric ratio was determined by capillary GC analysis and the configuration of the major diastereoisomer established by comparison of the NMR data of the synthetic mixture with an authentic sample of (Z)-tamoxifen (1).

nmr

FTIR

shows the typical spectra’s of pure tamoxifen citrate, PCL, a physical mixture of tamoxifen citrate and PCL and drug-loaded implants. The spectrum of tamoxifen citrate shows characteristic absorption bands at 3027 cm⁻¹ (=C-H stretching), 1507 and 1477 (C=C ring stretching) and 3180 cm ^-1 (-NH2). PCL displays a characteristic absorption band at strong bands such as the carbonyl stretching mode around 1727 cm⁻¹ (C=O), asymmetric stretching 2949 cm⁻¹ (CH ₂ ) symmetric stretching 2865 cm⁻¹ (CH ₂ ). No changes in the spectrum of the physical mixture and drug-loaded microspheres were evident by FTIR spectroscopy. The strong bands such as the carbonyl peak were clear at all points.

Figure 2: Transmission FTIR spectra of (a) tamoxifen-loaded implant, (b) physical mixture of drug+PCL, (c) pure PCL, (d) pure tamoxifen citrate

enlarged view

Figure 2: Transmission FTIR spectra of (a) tamoxifen-loaded implant, (b) physical mixture of drug+PCL, (c) pure PCL, (d) pure tamoxifen citrate

FTIR spectra of A) tamoxifen citrate; B) PLGA; C) mixture of drug and excipients; D) freshly prepared nanoparticles in the formulation (BS-3HS).

Mentions: The pure drug tamoxifen citrate, PLGA-85:15, PVA, a mixture of PLGA and PVA, and a mixture of tamoxifen citrate, PLGA, and PVA; and a freshly prepared formulation were mixed separately with IR grade KBr in the ratio of 1:100 and corresponding pellets were prepared by applying 5.5 metric ton pressure with a hydraulic press. The pellets were scanned in an inert atmosphere over a wave number range of 4000–400 cm−1 in Magna IR 750 series II, FTIR instrument (Nicolet, Madison, WI, USA).

dsc

Figure 3: DSC thermograms of pure tamoxifen (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant. The experiment was carried with crimped aluminum pans and a heating rate of 10ºC/min

DSC thermograms of pure tamoxifen (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant. The experiment was carried with crimped aluminum pans and a heating rate of 10ºC/min

xrd

$Figure 4: X-ray diffraction studies of pure drug (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant$

X-ray diffraction studies of pure drug (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant

synthesis

J.Chem. Research,1985(S) 116, (M) 1342 and 1986 (S) 58, (M) 0771.

EPROSARTAN MESYLATE

GENERIC, Uncategorized 1 Response »

Nov 022013

TEVETEN® (eprosartan mesylate) is a non-biphenyl non-tetrazole angiotensin II receptor (AT1) antagonist. A selective non-peptide molecule, TEVETEN® is chemically described as the monomethanesulfonate of (E)-2-butyl-1 -(p-carboxybenzyl)-α-2-thienylmethylimid-azole-5 -acrylic acid.

Its empirical formula is C23H24N2O4S•CH4O3S and molecular weight is 520.625. Its structural formula is:

EPROSARTAN MESYLATE

tevetenEprosartan mesilate, SK&F-108566-J(?, SK&F-108566, Teveten SB, Navixen, Regulaten, Tevetenz, Teveten

US 5656650

exp Aug 12, 2014

CAS EPROSARTAN

144143-96-4

133040-01-4


Chemical Name:	Eprosartan mesylate
Synonyms:	EPROSARTAN MESYLATE;Eprosartan Methanesulfonate;4-[[2-butyl-5-(2-carboxy-3-thiophen-2-yl-prop-1-enyl)-imidazol-1-yl]methyl]benzoic acid mesylate;4-({2-butyl-5-[(1E)-2-carboxy-2-(thiophen-2-ylMethyl)eth-1-en-1-yl]-1H-iMidazol-1-yl}Methyl)benzoic acid;(E)-α-[[2-Butyl-1-[(4-carboxyphenyl)Methyl]-1H-iMidazol-5-yl]Methylene]-2-thiophenepropanoic Acid Methanesulfonate;(αE)-α-[[2-Butyl-1-[(4-carboxyphenyl)Methyl]-1H-iMidazol-5-yl]Methylene]-2-thiophenepropanoic Acid MonoMethanesulfonate
CBNumber:	CB4842192
Molecular Formula:	C24H28N2O7S2
Formula Weight:	520.61832

Eprosartan is an angiotensin II receptor antagonist used for the treatment of high blood pressure. It is marketed as Teveten byAbbott Laboratories in the United States.It is marketed as Eprozar by INTAS Pharmaceuticals in India and by Abbott Laboratorieselsewhere. It is sometimes paired with hydrochlorothiazide, marketed in the US as Teveten HCT and elsewhere as TevetenPlus.

The drug acts on the renin-angiotensin system in two ways to decrease total peripheral resistance. First, it blocks the binding ofangiotensin II to AT₁ receptors in vascular smooth muscle, causing vascular dilatation. Second, it inhibits sympathetic norepinephrine production, further reducing blood pressure.

As with other angiotensin II receptor antagonists, eprosartan is generally better tolerated than enalapril (an ACE inhibitor), especially among the elderly.^[1]

^{Eprosartan is an angiotensin II receptor antagonist used for the treatment of high blood pressure. It acts on the renin-angiotensin system in two ways to decrease total peripheral resistance. First, it blocks the binding of angiotensin II to AT1 receptors in vascular smooth muscle, causing vascular dilatation. Second, it inhibits sympathetic norepinephrine production, further reducing blood pressure.}

Ruilope L, Jäger B, Prichard B (2001). “Eprosartan versus enalapril in elderly patients with hypertension: a double-blind, randomized trial”. Blood Press. 10 (4): 223–9. doi:10.1080/08037050152669747. PMID 11800061.

Teveten website

PAT APR EXP

Canada	2250395	2005-09-06	2017-03-26
Canada	2115170	2004-05-25	2012-08-12
United States	5656650	1994-08-12	2014-08-12
United States	5185351	1993-02-09	2010-02-09


Canada	2115170	2004-05-25	2012-08-12
United States	5656650	1994-08-12	2014-08-12
Canada	2250395	2005-09-06	2017-03-26

J Med Chem1991,34,(4):1514-7

J Med Chem1993,36,(13):1880-92

Synth Commun1993,23,(22):3231-48

AU 9056901, EP 403159, JP 91115278, US 5185351.

Drugs Fut1997,22,(10):1079

Eprosartan mesylate was developed successfully by SmithKline Beecham Corporation in 1997, and marketed in Germany in 1998 under the trade-name Teveten and in the United States later in 1999. Eprosartan mesylate, as an angiotensin II receptor blocker, is an antihypertensive drug of the latest generation. Eprosartan mesylate is potent to lower systolic and diastolic pressures in mild, moderate and severe hypertensive patients, and is safe and tolerable. Eprosartan mesylate is rapidly absorbed when administrated orally, with a bioavailability of 13% and a protein binding rate of 98%. The blood peak concentration and AUC (Area Under Curve) can be elevated by about 50% in patients with liver and kidney dysfunction, or fullness after administration, and can be elevated by 2 to 3 folds in elderly patients. Eprosartan mesylate has a structure shown as follows:

U.S. Pat. No. 5,185,351 discloses a method for preparing eprosartan mesylate using Eprosartan and methanesulfonic acid in isopropanol (U.S. Pat. No. 5,185,351, Example 41 (ii)). However, it is found when following this method for preparing eprosartan mesylate in industry, an esterification reaction can occur between eprosartan and isopropanol and the following two impurities can be generated:

In addition to the above two esterification impurities, the salifying method provided by the above patent is prone to produce isopropyl mesylate. Considering currently known potential risk of gene toxicity of methylsulfonic acid ester on human as well as the stringent requirements of methylsulfonic acid ester from the Europe and the America authorities, it is important to produce eprosartan mesylate in a non-alcohol solvent during the process of producing eprosartan mesylate, since it avoids the formation of methylsulfonic acid ester and the residue thereof in the final product. Since the dosage of eprosartan mesylate is high, it is particularly important to strictly control methylsulfonic acid ester in eprosartan mesylate.

In addition, for the above salifying method, solid eprosartan is suspended in propanol at a low temperature, then methanesulfonic acid is added, about ten seconds later a great deal of eprosartan mesylate precipitate is obtained. Therefore, solid eprosartan may be embedded by the precipitated eprosartan mesylate. Since isopropyl alcohol has a high viscosity at low temperature, a heavy filtering operation burden is needed to obtain solid from isopropanol, and the obtained solid contains quite an amount of isopropanol.

Eprosartan has been obtained by several different ways: 1) The iodination of 2-butylimidazole (I) with I2 and Na2CO3 in dioxane/water gives 2-butyl-4,5-diiodoimidazole (II), which is treated with benzyl chloromethyl ether (III) and K2CO3 in DMF yielding the imidazole derivative (IV). The condensation of (IV) with N-methyl-N-(2-pyridyl)formamide (V) by means of butyllithium in THF affords 1-(benzyloxymethyl)-2-butyl-4-iodoimidazole-5-carbaldehyde (VI), which is deprotected with concentrated HCl ethanol to give 2-butyl-4-iodoimidazole-5-carbaldehyde (VII). The acylation of (VII) with methyl 4-(bromomethyl)benzoate (VIII) by means of K2CO3 in hot DMF yields 4-(2-butyl-5-formyl-4-iodoimidazol-1 ylmethyl)benzoic acid methyl ester (IX), which is deiodinated by hydrogenation with H2 over Pd/C in methanol affording compound (X). The condensation of (X) with methyl 3-(2-thienyl)propionate (XI) by means of lithium diisopropylamide (LDA) in THF gives (XII), which is acylated with acetic anhydride and dimethylaminopyridine (DMAP) in dichloromethane yielding the corresponding acetate (XIII). Elimination of acetic acid from (XIII) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in hot toluene affords the expected propenoic ester (XIV), which is finally saponified with NaOH or KOH in ethanol/water.

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WO 1998035962 A1

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Pfizer 2013 and beyond

companies Comments Off

Oct 252013

Pfizer

Pfizer gets a lot of coverage in the financial papers–even if some of it turns out to be misguided.

For example, Pfizer got the media coverage all drug companies desire on May 4 from Seeking Alpha, http://seekingalpha.com/article/560531-pfizer-alzheimers-drugs-will-carry-stock-to-new-highs-in-2013

a stock market blog that provides free stock market analysis. A piece entitled “Pfizer: Alzheimer’s Drugs Will Carry Stock To New Highs In 2013” had a subheading “strong pipeline.”

Turns out that was too optimistic, as Pfizer’s Alzheimer’s drug–along with Johnson and Johnson’s–both failed to produce. But many stock analysts still hold hope that Pfizer has a new ‘cash cow’ coming down the pipeline.

Daily Finance http://www.dailyfinance.com/2012/09/07/a-peek-at-pfizers-pipeline/

notes that Pfizer currently has 87 drugs in its pipeline. While its true that most are in the early stages, 11 are ready to be reviewed by the FDA.

That number puts it ahead of most of its rivals, with Eli Lilly, a close second, having 63 drugs in Phases 1-3, plus one currently being reviewed. Bristol-Myers Squibb has 46 drugs in development, 7 under review, Merck has 35 drugs in Phase 2 or 3 with two under review, and Johnson and Johnson has 18 drugs that are already in Phase 3 clinical trials or up for FDA approval.

But, of course, as the journal points out, “Quality trumps quantity. . . . One or two blockbusters can be better than several lower-revenue drugs.”

So what does Pfizer have up its sleeve that might begin to fill the very big shoes of Lipitor?

Well, the company has diversified the therapeutic areas under research, with 26% of R&D efforts going toward oncology treatments, 20% to neuroscience and pain, 17% to cardiovascular and metabolic diseases, 14% to inflammation and immunology, 5% to vaccines, and 18% toward ‘other.’

Pfizer has several medicines for diabetes alone coming up, in Phase I and Phase II trials, almost all meant to treat type 2 diabetes.

But, notes Seeking Alpha,http://seekingalpha.com/article/560531-pfizer-alzheimer-s-drugs-will-carry-stock-to-new-highs-in-2013

its blockbuster potential in this area is limited by the existing treatments of Merck and Sanofi. 10% of Sanofi’s total sales come from Lantus,

a diabetes drug useful for both types 1 and 2, and Merck made $1.3 billion off its Januvia

franchise in the first quarter of this year alone.

So hopes are pinned on Pfizer’s tofacitinib, currently under FDA review, as the treatment with the potential to earn $1 billion or more in sales, easing the gaping wound left by Lipitor. Tofacitinib prompts such high hopes because it might possibly treat rheumatoid arthritis, psoriasis, and irritable bowel syndrome. Some analysts have pinned this as the cash cow Pfizer so badly needs to replace treatments lost to the patent cliff.

Tofacitinib

http://seekingalpha.com/article/812981-pfizers-success-with-its-jak-inhibitor

If it gets approved, Tofacitinib would be first treatment for rheumatoid arthritis (RA) in a new class of medicines (known as Jenus kinase, or JAK, inhibitors), and the first JAK inhibitor approved for rheumatoid arthritis.

Tofacitinib showed statistically significant improvement compared to placebo in decreasing the symptoms of RA (as measured by 20% improvement in the American College of Rheumatology scale), in improving physical function (as measured by mean change in Health Assessment Questionnaire-Disability Index), and in leading to remission (as measured by Disease Activity Score 28 ESR).

Joel Kremer, MD, chief of medicine at Albany Medical College in N.Y., after analyzing the data, commented, “Tofacitinib appears to reduce the signs and symptoms of rheumatoid arthritis very quickly. We hope that after carefully considering the benefit/risk equation, this compound will provide an additional valuable treatment option for patients who have experienced inadequate response to prior treatments.”

Pfizer also believes its blood thinner Eliquis, which it is developing with Bristol-Myers Squibb (see below) could be a big money-maker.

apixaban, eliquis

Alzheimer’s Image Problem Solved

Uncategorized Comments Off

Oct 252013

Copper-based radiopharmaceuticals for diagnostic imaging can target the amyloid-β plaques implicated in Alzheimer’s disease

http://www.chemistryviews.org/details/news/5384281/Alzheimers_Image_Problem_Solved.html

Alzheimer’s Image Problem Solved

ViiV Healthcare files new drug application for three-drug HIV pill with US FDA

NDA Comments Off

Oct 242013

ViiV Healthcare, a joint venture involving GlaxoSmithKline (GSK), Pfizer and Shionogi, has submitted a New Drug Application (NDA) to the US Food and Drug Administration (FDA) for its investigational single-tablet regimen (STR) combining dolutegravir, abacavir and lamivudine for treatment of HIV-1 patients.

click hereViiV Healthcare files new drug application for three-drug HIV pill with US FDA

Ranbaxy obtains approval to market malaria drug in India

INDIA Comments Off

Oct 232013

Ranbaxy Laboratories has secured approval from India’s Central Drugs Standard Control Organisation (CDSCO) to produce and market its Synriam drug in the country to treat malaria caused by the Plasmodium vivax parasite in adults.

Ranbaxy obtains approval to market malaria drug in India CLICK HERE

http://www.pharmaceutical-technology.com/news/newsranbaxy-obtains-approval-market-malaria-drug-india?WT.mc_id=DN_News

AltheRx obtains US patent for solabegron combination therapy for OAB treatment

phase 2, Uncategorized Comments Off

Oct 212013

solabegron

AltheRx Pharmaceuticals has received a notice of allowance for its patent application from the US Patent and Trademark Office (USPTO) for the use of solabegron, a beta 3-adrenergic receptor agonist, in combination with antimuscarinics at both therapeutic and sub-therapeutic doses, for the treatment of overactive bladder (OAB).

AltheRx obtains US patent for solabegron combination therapy for OAB treatment

http://www.pharmaceutical-technology.com/news/newsaltherx-obtains-us-patent-for-solabegron-combination-therapy-for-oab-treatment?WT.mc_id=DN_News

Solabegron (GW-427,353) is a drug which acts as a selective agonist for the β3 adrenergic receptor. It is being developed for the treatment of overactive bladder andirritable bowel syndrome.^[1]^[2]^[3] It has been shown to produce visceral analgesia by releasing somatostatin from adipocytes.,^[4]^[5]

Solabegron was discovered by GlaxoSmithKline and acquired by AltheRx in March 2011. Solabegron relaxes the bladder smooth muscle by stimulating beta-3 adrenoceptors, a novel mechanism compared to older established drug treatments for overactive bladder syndrome such as the anticholinergic agents. Astellas Pharma have developed the first commercially available β3 adrenergic receptor, mirabegron, which is now licensed in Japan^[6] and the US^[7] for overactive bladder. Mirabegron is not licensed for irritable bowel syndrome.

A Phase II study of Solabegron for overactive bladder (OAB) looked at 258 patients with moderate to severe incontinence experiencing an average of 4.5 wet episodes per day. Results demonstrated a statistically significant improvement with Solabegron as compared to placebo, as measured by the percent reduction of the number of wet episodes and the absolute number of daily voids.

A Phase II study for irritable bowel syndrome (IBS) evaluated 102 patients with IBS. Solabegron demonstrated significant reduction in pain associated with the disorder and a trend for greater improvement in the quality of life, compared to placebo.

Both Phase II studies indicated a tolerability profile for Solabegron that was similar to placebo. The OAB patients did not suffer from dry mouth, constipation, increase in heart rate or cognitive issues.

AltheRx is currently preparing to advance Solabegron into a large clinical study in OAB.

Synthesis

Hicks A, McCafferty GP, Riedel E, Aiyar N, Pullen M, Evans C, Luce TD, Coatney RW, Rivera GC, Westfall TD, Hieble JP. GW427353 (solabegron), a novel, selective beta3-adrenergic receptor agonist, evokes bladder relaxation and increases micturition reflex threshold in the dog. Journal of Pharmacology and Experimental Therapeutics. 2007 Oct;323(1):202-9.doi:10.1124/jpet.107.125757 PMID 17626794
Grudell AB, Camilleri M, Jensen KL, Foxx-Orenstein AE, Burton DD, Ryks MD, Baxter KL, Cox DS, Dukes GE, Kelleher DL, Zinsmeister AR. Dose-response effect of a beta3-adrenergic receptor agonist, solabegron, on gastrointestinal transit, bowel function, and somatostatin levels in health.American Journal of Physiology. Gastrointestinal and Liver Physiology. 2008 May;294(5):G1114-9. PMID 18372395
Kelleher DL, Hicks KJ, Cox DS, et al. Randomized, double-blind, placebo (PLA)-controlled, crossover study to evaluate efficacy and safety of the beta 3-adrenergic receptor agonist solabegron (SOL) in patients with irritable bowel syndrome (IBS). Neurogastroenterol Motil 2008;20 (Suppl 2):131.
Cellek S, Thangiah R, Bassil AK, Campbell CA, Gray KM, Stretton JL, Lalude O, Vivekanandan S, Wheeldon A, Winchester WJ, Sanger GJ, Schemann M, Lee K. Demonstration of functional neuronal beta3-adrenoceptors within the enteric nervous system. Gastroenterology. 2007 Jul;133(1):175-83.
Schemann M, Hafsi N, Michel K, Kober OI, Wollmann J, Li Q, Zeller F, Langer R, Lee K, Cellek S. The beta3-adrenoceptor agonist GW427353 (solabegron) decreases excitability of human enteric neurons via release of somatostatin.Gastroenterology 2009 Sep 25. [Epub ahead of print]
http://www.ncbi.nlm.nih.gov/pubmed/22384458
http://chembl.blogspot.co.uk/2012/07/new-drug-approvals-2012-pt-xiv.html

MONOCLONAL ANTIBODIES

MONOCLONAL ANTIBODIES Comments Off

Oct 172013

PPT from many87

Production of MAb

Fig.1 Production of MAb

Large Scale Production Of MAbs:

Commercially, on large scale, MAbs are produced by two methods.

(a) Ascites production in mice

(b) In-vitro fermentation

The production method is summarized in Fig.no.2a & 2b.

a) Ascites Production In Mice:

The first monoclonal antibodies approved by FDA for therapeutic use OKTS, is produced by ascitic technology¹⁹.

In this method hybridoma cells are injected into peritoneal cavity of histocompatible mice. The mice are pretreated by i.p. injection of Pristane to irritate the peritoneal cavity which facilitates the growth of ascitic tumor. The fluid produced may contain the high concentration of secreted MAbs, 2 to 20 μg / ml and 2 to 6 ml or more can be harvested per mouse. Comparison of different MAb production^22,23 methods is shown inTable 1.

Drawbacks of this method are:

1. It is very costly, very difficult and not reliable.

2. Product may get contaminated with mouse immunoglobulins and also with other mouse proteins.

3. Viruses can be introduced as contaminants.

4. Antibody yield is often less as compared to other methods.

b) In-Vitro Fermentation:

In this method, the cells are grown and gradually moved to larger and larger culture ensuring exponential growth. Typical antibody levels in the culture supernatant ranges from 5-50 μg/ml depending on the individual clone and on cell density. When more production of antibody is required 1-litre cultures in roller bottles are used. Required cells are removed from rest of media by centrifugation or filtration, generally followed by ultra filtration step for concentrating the filtrate by up to 20 folds.

Advantages of this method are:

(1) As serum required in culture media is reduced, it is cost effective.

(2) There will not be any contamination with mouse immunoglobulin.

But the major drawback is that of contamination of final product with serum or protein based growth factors.

Table 1: Comparison of different MAb production methods.

Production system	Scale	Volume (ml)	Concentration (mg/ml)	Production time (weeks)	Quality
Ascites (in vivo)	20-250 mg	5-10	< 20	2-3	Low
Stir growth	—	100-2500	0.01-0.1	2-3	High
Dialysis membrane	< 50 mg	10-25	0.1-1.5	2-5	High
Roller bottles	< 2 gm	100-2000	0.01-0.2	2-6	High
Hollow fiber	0.15-30 gm	25-1000	0.2-0.3	3-12	High
Fermentor	2-100 gm	< 2000 lit	0.05-0.5	2-12	High

MAb Production

Fig. 2a: MAb Production (Flowchart)

Freeze Dried MAb Production

Fig. 2b: Freeze Dried MAb Production (Flowchart)

i) Purification:

Contamination, during production process, such as protein, nucleic acid, endotoxins, immunoglobulin and adventitious agent can be removed by purification method. The purification methods such as precipitation with ammonium sulphate, zone electrophoresis, ion exchange chromatography, hydrophobic interaction chromatography, gel filtration and affinity chromatography are used¹⁹.

· Affinity chromatography is often used for initial purification.

· Ion exchange chromatography is used for removing endotoxins and DNA.

· Gel filtration chromatography can remove both high and low molecular form of monoclonal antibodies and it is usually used as the final polishing step.

j) Characterization:

The final determination of monoclonality requires biochemical and biophysical characterization of the immunoglobulin. It is also characterized immunochemically to define its affinity for antigen, its immunoglobulin subclass, the epitopes for which it is specific and the effective number of binding site that it possesses¹⁹.

k) Final Processing:

Depending upon the intended application, the antibody may be conjugated to specific radionuclide or toxin. Then the stabilizing agent is added, and the product is filled into final container under inert gas or other specialized conditions. Lyophillization is frequently applied to get freeze dried product.

Antigenicity Of Murine MAb:

The main problem for mouse MAb is that, human body recognizes it as a foreign agent and produces antibodies against such mouse MAb. The induced human anti-mouse antibodies (HAMA) quickly reduce the effectiveness of mouse MAb and also their interaction may lead to allergic reactions.

To overcome the problem, Human MAbs can be used. Though difficult, this is possible by fusion of EBV (Epstein Barr Virus) transformed human B-lymphocyte with appropriate fusion partners²¹. EBV is a lymphotrophic DNA herpes virus which is capable of converting normal B-lymphocytes of human and/or mouse into cancer cell having proliferating capacity in vitro. But the presence of EBV as contaminant can pose a problem of producing cancer²⁴.

Even the human-human hybridomas producing MAbs have been produced ^25,26. Olsson and Kaplan in the year 1980 produced first human-human myeloma (SKO-007), against the hapten 2, 4-dinitrophenyl (DNP)¹⁹.

The routine production of human MAbs is prevented due to following reason:-

Sources of antibody producing cells²⁷.
Reliable methods for lymphocytes immortalization.
Stability²⁸ and antibody producing capacity.
Administration of some antigens to humans could endanger their health²⁹.
Recovery of B-lymphocytes from the spleen of human is impracticable.
The fusion of human lymphocytes with human lymphoblastoid cell lines is a very inefficient process.
Low production yield of human monoclonal antibody.

Hence, other alternatives methods come forth.

Advantages Of MAbs:

Pure one molecular species with high specificity for a particular antigenic target.
Anti-serum titer values are high.
Antibodies with high avaidity can be produced.
In vitro and in vivo production is possible.
Radiolabelling and fluorescent conjugation of monoclonal antibody are easy.

Disadvantages Of MAbs:

Initial cost involved in the technique is high. However, continuous production is somewhat economical.
Methods are time consuming.
Antigenicity of Murine MAb.
MAbs have comparatively less complement fixing ability than that of convectional antiserum.
MAbs are highly selective for a particular single antigenic determinant. This renders them incapable of distinguish between different molecules, cells bearing the chemical structure or determinants except one against which it is targeted.
The high antibody avidity (energy of binding to an antigen) of MAbs is advantageous for immunoassay but some property is undesirable for purification process.

Formulation Development of Insoluble Drugs

drugs, GENERIC, MANUFACTURING, nanotechnology Comments Off

Oct 152013

Formulation development of insoluble drugs has always been a challenge in pharmaceutical development. This presentation reviews some current options to old problem.