Nafarelin acetate

Description

Nafarelin is an agonist of gonadotropin-releasing hormone (GNRH). It is a long-acting agent that, after an initial increase in sex hormone levels, decreases the level of circulating gonadotropins and sex hormones. In vivo, nafarelin (0.5-2.0 μg/kg, s.c.) reduces plasma levels of luteinizing hormone and testosterone (Item Nos. 15645 | ISO60154) as well as testicular volume, sperm count, sperm motility, and duration of ejaculation in male dogs. Nafarelin (32 μg/animal per day) inhibits estrus in female beagle dogs. It also reduces the volume of endometrial tissue in a rat model of endometriosis. Formulations containing nafarelin have been used in the treatment of endometriosis and central precocious puberty.

Originator

Nafarelin Acetate,Bachem AG

Definition

ChEBI: Nafarelin acetate is an acetate salt obtained by reaction of nafarelin with one equivalent of acetic acid. It has a role as a gonadotropin releasing hormone agonist and an anti-estrogen. It contains a nafarelin.

Manufacturing Process

In the reaction vessel of a Beckman 990 Peptide Synthesizer was placed 0.8 g (0.8 mmol) of benzhydrylamino-polystyrene-divinylbenzene resin (Lab Systems, Inc.) as described by Rivaille, supra. Amino acids were added sequentially to this resin by means of the usual methods of Boc-strategy of peptide synthesis on above copolymer.
The resin was coupled sequentially with a 2.5 molar excess of each protected amino acid and DCC. Thus, the resin was treated during successive coupling cycles with 0.433 g Boc-Gly-OH, 0.432 g Boc-Pro-OH, 0.857 g Boc-Arg(Tosyl)- OH, 0.462 g Boc-Leu-OH, 0,504 g Boc-3-(2-naphthyl)-D-alanine and 0.272 g 1-hydroxybenzotriazole, 0.724 g N-Boc, O-2-bromobenzoyloxycarbonyl-Ltyrosine, 0.59 g Boc-Ser(Benzyl)-OH, 0.608 g Boc-Trp-OH, 0.654 g BocHis(Tosyl)-OH and 0.524 g pyroglutamic acid. A coupling cycle for one amino acid and completeness of the reaction is checked by the ninhydrin method of E. Kaiser, et al., Anal. Biochem., 34, 595 (1970).
The resin was removed from the reaction vessel, washed with CH2Cl2, and dried in vacuo to yield 2.0 g of protected polypeptide resin.
The polypeptide product was simultaneously removed from the resin and completely deprotected by treatment with anhydrous liquid HF. A mixture of 2.0 g of protected polypeptide resin and 2 mL of anisole (scavenger) in a KelF reaction vessel was treated with 20 mL of redistilled (from CoF3) anhydrous liquid HF at 0°C for 30 minutes. The HF was evaporated under vacuum and the residue of (pyro)-Glu-His-Trp-Ser-Tyr-3-(2-naphthyl)-D-alanyl-Leu-ArgPro-Gly-NH2,as its HF salt, was washed with ether. The residue was then extracted with glacial acetic acid. The acetic acid extract was lyophilized to yield 0.8 g of crude material. The crude polypeptide was loaded on a 4x40 cm. Amberlite XAD-4 column (polystyrene-4% divinylbenzene copolymer) and eluted with a concave gradient from water (0.5 L) to ethanol (1 L). The tubes containing fractions from effluent volume 690 mL to 1,470 mL were pooled and stripped to dryness to yield 490 mg of partially purified polypeptide.
A 150 mg sample of the partially purified product was subjected to partition chromatography on a 3 times 50 cm. column of Sephadex G-25 using the solvent system 1-butanol/toluene/acetic acid/water containing 1.5% pyridine in the ratios 10:15:12:18. The pure fractions were pooled on the basis of thin layer chromatography (silica gel; BuOH/H2O/HOAc/EtOAc; 1:1:1:1) and HPLC (5 micron, reverse phase, octadecylsilyl packing; 40% 0.03 M NH4OAc/60% acetonitrile). The desired product came off the column in fractions from effluent volume 1,000 mL to 1,400 mL (Rf 0.1). The pure fractions were pooled, stripped to dryness, taken up in H2O, and lyophilized to yield 57 mg of pure pyro-glutamyl-histidyl-tryptophylseryl-tyrosyl-3-(2-naphthyl)-D-alanylleucyl-arginylprolyl-glycinamide, as its acetic acid addition salt, [α]D25-27.4° (c 0.9, HOAc), m.p. 185°-193°C (dec.).

Therapeutic Function

Gonadotropic

Raw materials

Preparation Products