Specific HPLC assay for serum nifedipine.

Area of Science:

• Pharmacology
• Analytical Chemistry
• Clinical Medicine

Background:

• Nifedipine is a crucial cardiovascular drug.
• Accurate serum level monitoring is essential for therapeutic efficacy and safety.
• Existing methods for nifedipine quantification may lack sensitivity or specificity.

Purpose of the Study:

• To develop and validate a sensitive, specific, and reproducible assay for nifedipine in human serum.
• To investigate the pharmacokinetic variability of nifedipine absorption.
• To compare nifedipine absorption rates in normotensive and hypertensive individuals.

Main Methods:

• Development of a reverse-phase High-Performance Liquid Chromatography (HPLC) assay.
• Extraction of nifedipine from serum using an ether solvent at pH 9.
• Quantification using nisoldipine as an internal standard and spectrophotometry at 350 nm.
• Pharmacokinetic analysis of nifedipine absorption after sublingual administration.

Main Results:

• The developed HPLC assay demonstrated high sensitivity (10 ng/ml detection limit) and reproducibility (3.3% CV).
• No significant interference was observed from commonly co-administered drugs.
• Sublingual nifedipine administration showed wide inter-individual variability in peak serum levels (48-148 ng/ml) and absorption times (30- >60 min).
• No significant differences in absorption rates were found between normotensive and hypertensive subjects.

Conclusions:

• The novel HPLC method provides a reliable tool for therapeutic drug monitoring of nifedipine.
• Significant inter-individual variability exists in nifedipine absorption, impacting its clinical use.
• Blood pressure status does not appear to influence the absorption rate of sublingually administered nifedipine.