Rectiv - Pharmaceutical Information, Clinical Trials, Detailed Pharmacology, Toxicology
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Rectiv - Scientific Information

Manufacture: Forest Laboratories, Inc.
Country: United States
Condition: Anal Fissure and Fistula
Class: Antianginal agents, Vasodilators
Form: Cream, gel, liniment or balm, lotion, ointment, etc
Ingredients: nitroglycerin, propylene glycol, lanolin, sorbitan sesquioleate, paraffin wax, white petrolatum

Description

Nitroglycerin is 1,2,3,-propanetriol trinitrate, an organic nitrate whose structural formula is as follows:


and whose molecular weight is 227.09. RECTIV (nitroglycerin) Ointment 0.4% contains 0.4% nitroglycerin w/w (4 mg nitroglycerin/1 g ointment), propylene glycol, lanolin, sorbitan sesquioleate, paraffin wax, and white petrolatum. RECTIV (nitroglycerin) Ointment 0.4% is available in tubes with a one-inch dosing line on the carton allowing the measurement of approximately 375 mg of nitroglycerin ointment 0.4% (1.5 mg nitroglycerin) for application.

Clinical Pharmacology

Mechanism of Action

Nitroglycerin forms free radical nitric oxide (NO), which activates guanylate cyclase, resulting in an increase of guanosine 3',5'-monophosphate (cyclic GMP) in smooth muscle and other tissues. This leads to dephosphorylation of myosin light chains, which regulates the contractile state in smooth muscle and results in vasodilatation.

Pharmacodynamics

The principal pharmacological action of nitroglycerin is relaxation of vascular smooth muscle. Intra-anal application of nitroglycerin reduces sphincter tone and resting intra-anal pressure.

Pharmacokinetics

Absorption

In six healthy subjects, the average absolute bioavailability of nitroglycerin applied to the anal canal as a 0.2% w/w ointment was approximately 50% of the 0.75 mg nitroglycerin dose.

Distribution

The volume of distribution of nitroglycerin following intravenous administration is about 3 L/kg. At plasma concentrations between 50 and 500 ng/mL, the binding of nitroglycerin to plasma proteins is approximately 60%, while that of 1,2- and 1,3-dinitroglycerin is 60% and 30%, respectively.

Metabolism

Nitroglycerin is metabolized by a liver reductase enzyme to glycerol di- and mononitrate metabolites and ultimately to glycerol and organic nitrate. Known sites of extrahepatic metabolism include red blood cells and vascular walls. In addition to nitroglycerin, the two major metabolites, 1,2- and 1,3- dinitroglycerols are found in plasma. The contribution of metabolites to the relaxation of the internal anal sphincter is unknown. The dinitrates are further metabolized to nonvasoactive mononitrates and ultimately to glycerol and carbon dioxide.

Elimination

Metabolism is the primary route of drug elimination. Nitroglycerin plasma concentrations decrease rapidly with a mean elimination half-life of two to three minutes. Half-life values range from 1.5 to 7.5 minutes. Clearance (13.6 L/min) greatly exceeds hepatic blood flow.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

Animal carcinogenicity studies with topically applied nitroglycerin have not been performed.

Rats receiving up to 434 mg/kg/day of dietary nitroglycerin for 2 years developed dose-related fibrotic and neoplastic changes in liver, including carcinomas, and interstitial cell tumors in testes. At the highest dose, the incidence of hepatocellular carcinomas was 52% compared to 0% in untreated controls. Incidence of testicular tumors were 52% vs. 8% in controls. Lifetime dietary administration of up to 1058 mg/kg/day of nitroglycerin was not tumorigenic in mice.

Nitroglycerin was mutagenic in the in vitro bacterial reverse mutation (Ames) assay with Salmonella typhimurium. A similar mutation in this S. typhimurium was also reported with other NO donors. There was no evidence of clastogenic potential in multiple assays including a rodent dominant lethal assay, an in vitro Chinese Hamster Ovary assay that was conducted in the absence of metabolic activation, and several in vivo chromosomal aberration assays conducted in rats and dogs.

In a three-generation reproduction study, rats received dietary nitroglycerin at doses up to approximately 434 mg/kg/day for 6 months prior to mating of the F0 generation with treatment continuing through successive F1 and F2 generations. The high dose was associated with decreased feed intake and body weight gain in both sexes at all matings. No specific effect on the fertility of the F0 generation was seen. Infertility noted in subsequent generations, however, was attributed to increased interstitial cell tissue and aspermatogenesis in the high-dose males.

Clinical Studies

RECTIV ointment was evaluated in a 3-week double-blind, randomized, multi-center, placebo-controlled study. Patients with a painful chronic anal fissure for at least 6 weeks and moderate or severe pain prior to treatment (≥ 50 mm on the 100 mm visual analog scale, VAS) were randomized to receive 0.4% (1.5 mg) nitroglycerin or placebo ointment applied to the anal canal every 12 hours. Pain as assessed by the change in VAS from baseline to Days 14-18 was lower in patients receiving 0.4% ointment compared to placebo. The mean change from baseline was 44 mm for RECTIV and 37 mm for placebo. The difference in the mean change in pain between RECTIV and placebo was -7.0 mm (95% Confidence Interval: -13.6 to -0.4 mm).