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Pharmacokinetics of m-nifedipine in rabbits after intravenous injection
Aim:
To study the dose effects on pharmacokinetics of m-Nif.
Methods:
Fifteen rabbits were divided into 3 groups receiving i.v. m-Nif 0.5, 1, and 2 mg.kg-1. Plasma levels of m-Nif were determined with HPLC method.
Results:
The concentration-time data were fitted with 2-compartment model. After i.v. 1 mg.kg-1, the parameters were: Vd = 0.37 +/- 0.10 L.kg-1, T1/2 alpha = 6.4 +/- 2.9 min, T1/2 beta = 84 +/- 22 min, AUC = 94 +/- 16 mg.min.L-1, Cl = 0.65 +/- 0.13 L.kg-1.h-1. No statistically significant difference was found in Cl and T1/2 beta between 3 dose groups. AUC (standardized to body weight) was correlated with doses.
Conclusions:
m-Nif was distributed widely and eliminated at a fairly rapid rate in the rabbits. No dose-dependent pharmacokinetics was found after i.v. m-Nif 0.5-2 mg.kg-1. m-Nifedipine, 2, 6-dimethyl-3, 5-dicarbomethoxy-4-(3'-nitrophenyl)-1, 4-dihydropyridine (m-Nif) is a new calcium channel blocker. Dihydropyridine calcium channel antagonists are mainly used for the treatment of hypertension and angina[1]. Nifedipine is susceptible to photodegradation, but m-Nif is stable when exposed to light. The 2 drugs have the same antihypertensive effect[2]. So far, no report has been found on pharmacokinetics of m-Nif. Using a high performance liquid chromatographic (HPLC) method, we studied the dose effects on the pharmacokinetics of i.v. m-Nif 0.5, 1, and 2 mg.kg-1 in conscious rabbits.
Insights
This study found that m-Nifedipine (m-Nif) exhibits dose-independent pharmacokinetics in rabbits within the tested intravenous dosage range. The drug is widely distributed and rapidly eliminated, suggesting consistent absorption and metabolism across different doses.
Area of Science:
- Pharmacology
- Drug Metabolism and Pharmacokinetics
Background:
- m-Nifedipine (m-Nif) is a novel, photostable dihydropyridine calcium channel blocker.
- Dihydropyridine calcium channel antagonists are crucial for managing hypertension and angina.
- Unlike nifedipine, m-Nif offers enhanced stability when exposed to light while maintaining similar antihypertensive efficacy.
Purpose of the Study:
- To investigate the dose-dependent pharmacokinetic profile of m-Nifedipine (m-Nif) following intravenous administration in rabbits.
- To establish baseline pharmacokinetic parameters for m-Nif in an animal model.
Main Methods:
- Conscious rabbits (n=15) were administered intravenous m-Nif at doses of 0.5, 1, and 2 mg/kg.
- Plasma concentrations of m-Nif were quantified using a validated High-Performance Liquid Chromatography (HPLC) method.
- Pharmacokinetic parameters were determined by fitting concentration-time data to a two-compartment model.
Main Results:
- The pharmacokinetic analysis revealed wide distribution and relatively rapid elimination of m-Nif in rabbits.
- Key parameters at 1 mg/kg i.v. included Vd (0.37 L/kg), T1/2 alpha (6.4 min), T1/2 beta (84 min), AUC (94 mg·min/L), and Cl (0.65 L/kg/h).
- No statistically significant differences in clearance (Cl) or terminal half-life (T1/2 beta) were observed across the tested dose groups, although AUC (normalized for body weight) showed a correlation with dose.
Conclusions:
- Intravenous administration of m-Nif (0.5-2 mg/kg) in rabbits does not result in dose-dependent pharmacokinetics.
- m-Nif is characterized by broad distribution and rapid elimination in this animal model.
- These findings provide essential pharmacokinetic data for m-Nif, a promising alternative to existing calcium channel blockers.