C08CA03 - Isradipine |
Propably not porphyrinogenic |
PNP |
Side effects
Abdominal discomfort is a common side effect of isradipine.
Rationale
Isradipine is a substrate CYP 3A4. It is also a week inhibitor of CYP 3A4, but it is not a mechanism- based inhibitor.
Chemical description
Dihydropyridine calcium antagonist.
Therapeutic characteristics
Isradipine is used in the treatment of essential hypertension.
Metabolism and pharmacokinetics
Isradipine is a substrate of CYP3A4. At least 6 biologically inactive metabolites have been identified and mainly consist of mono acids of the pyridine derivative and a cyclic lactone product (Micromedex).
In an in vitro study isradipine was found to be a week competitive inhibitor (Wang 1999).
The results of an in -vivo study indicate that isradipine is not a clinically significant inhibitor of CYP3A4 in humans (Beckman 1999) and the SPC also states that isradipine does not seem to inhibit the cytochrome P450 enzymes, in particular CYP3A4, to a clinically significant extent.
Personal communication
Uneventful use reported in one patient (C. Andersson).
IPNet drug reports
Uneventful use reported in 1 patient with acute porphyria.
References
- Scientific articles
- Backman JT, Wang JS et al. Mibefradil but not isradipine substantially elevates the plasma concentrations of the CYP3A4 substrate triazolam. Clin Pharmacol Ther. 1999 Oct;66(4):401-7. #1286
- Wang JS, Wen X, et al. Midazolam alpha-hydroxylation by human liver microsomes in vitro: inhibition by calcium channel blockers, itraconazole and ketoconazole. Pharmacology & toxicology , 1999, Vol.85(4), p.157-161 PMID 10563513. #4405
- Drug reference publications
- Micromedex® 2.0 (online). Labetalol. Comparative efficacy. (Drugdex System). (Sist oppdatert:2. november 2015). #1287
- Summary of Product Characteristics
- The electronic Medicines Compendium (emc). Summary of Product Characteristics (SPC). Prescal. #1288
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