Pharmacokinetics of verapamil and its metabolite norverapamil in rats with hyperlipidaemia induced by poloxamer 407

1. In this study, the pharmacokinetics of verapamil and its active metabolite norverapamil were evaluated following intravenous and oral administration of 10?mg/kg verapamil to rats with hyperlipidaemia (HL) induced by poloxamer 407 (HL rats).

2. The total area under the plasma concentration time curve (AUC) of verapamil in HL rats following intravenous administration was significantly greater (by 11.2%) than in control rats due to their slower (by 11%) non-renal clearance. The oral AUC of verapamil in HL rats was also significantly greater (by 116%) compared with controls, with a larger magnitude than the data observed following intravenous administration. This may have been a result of the decreased intestinal metabolism of verapamil in HL rats.

3. The AUC of norverapamil and AUC_norverapamil/AUC_verapamil ratios following intravenous and oral administration of verapamil were unchanged in HL rats.

4. Assuming that the HL rat model qualitatively reflects similar changes in patients with HL, the findings of this study have potential therapeutic implications. Further studies in humans are required to determine whether modification of the oral verapamil dosage regimen in HL states is necessary.