Nifedipine Amoxicillin

J-F Westphal, J-H Trouvin, A Deslandes, C Carbon. Nifedipine enhances amoxicillin absorption kinetics and bioavailability in human. J Pharmacol Exp Ther 255 312-317, 1990. 

Co-codamol is a combination of paracetamol (nonnapioid analgesic) and codeine (opioid analgesic). One of the side-effects of opioids is constipation. Naprosyn is a proprietary (trade name) preparation of the non-steroidal antiinflammatory drug naproxen Adalat is a proprietary preparation of the calcium-channel blocker nifedipine Amoxil is a proprietary preparation of the beta-lactam amoxicillin and Dulco-lax is the brand name of the stimulant laxative bisacodyl. 

An active dipeptide transport system that depends on hydrogen ions takes up non-ester amino-beta-lactams (penicillin, amoxicillin, and oral first-generation cephalosporins) (337-339) and specific cephalosporins that lack the alpha-amino group (cefixime, ceftibuten, cefdinir, cef-prozil) (340,341). Nifedipine increases amoxiciUin and cefixime absorption, probably by stimulating the dipeptide transport system, since the serum concentrations of passively absorbed drugs and intestinal blood flow did not change (342-344). 

Nifedipine increases the absorption of amoxicillin from the gut but this is unlikely to be clinically important. Nafcillin increases the clearance of nifedipine, but the clinical significance of this is unclear. 

In 8 healthy subjects when amoxicillin 1 g was given 30 minutes after a 20-mg nifedipine capsule, the peak serum amoxicillin levels were raised by 33%, the bioavailability was raised by 21% and the absorption rate was raised by 70%. The authors speculate that the uptake of amoxicillin through the gut wall is increased by nifedipine in someway. There would seem to be no good reason for avoiding concurrent use as overall the bioavailability was not significantly altered. 

Westphal J-F, Trouvin J-H, Deslandes A, Carbon C. Nifedipine enhances amoxicillin absccp-tier) l etics and bioavailability in humans. Ther (1990) 255, 312-17. 

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