Category Archives: Drug-Drug Interactions

Methylphenidate bioavailability increased by alcohol

This four-way, unblinded, uncontrolled comparison by University of Michigan pharmacist H.J. Zhu and colleagues (from the University of South Carolina, Medical University of South Carolina, and the University of Tennessee) (H.J. Zhu and colleagues, Journal of Clinical Psycho- pharmacology 37(4): 419-428, 2017) regretably suffers from a lack of blindedness and placebo control that its torturously long discussion leaves unassuaged.

The … Read the rest

More about lamotrigine-valproate interactivity (mitigated by an inducer?)

Corroborating a previously reported finding that valproate reduces the clearance of lamotrigine in adults with bipolar disorder (thereby raising its blood concentrations), and suggesting that it may do so in pediatric epileptic youth, is a study reported recently on the Web (B. Koriskova and colleagues, Basic and Clinical Pharmacology and Toxicology, published online, ahead of print, on January 25, … Read the rest

Cytochrome P450 metabolic enzyme substrates, inhibitors, and inducers (continually updated)

Knowing whether drugs inhibit or induce cytochrome enzymes affecting bioavailability of coadministered drugs and heeding that knowledge with prescription preferences or dosage adjustments is qualitatively correct practice. More complex and less well-documented are risk-benefit considerations about when and by how much to do so. That the latter depend upon the former is rationale enough to justify commiting to memory (hippocampal … Read the rest

Drug-drug interactions of lamotrigine with other antiepileptics

Increasingly prescribed for acute treatment and prophylaxis of bipolar depression, lamotrigine will doubtless become a participant in pharmacokinetic drug-drug interactions of patients whose normative polytherapeutic regimens will include three to four other drugs prescribed for psychiatric or medical indications. Disproportionately represented among the latter are antiepileptic drugs, including carbamazepine, valproic acid, and others, such as oxcarbazepine and topiramate, that … Read the rest

More than one potential source of induction of aripiprazole metabolism

A case report cum literature review published last year (I.R. McGrane and colleagues, Journal of Pharmacy Practice, 2017 January 1:897190017710523. doi: 10.1177/0897190017710523; published on the Web) corroborated a handful of earlier reported cases suggesting that aripiprazole bioavailability diminishes during coadministration of carbamazepine (attributed by authors of early reports to induction of CYP3A4 by carbamazepine).  The more recent report by McGrane … Read the rest