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Scott C Armstrong

Publications and source records attributed to Scott C Armstrong.

8 recordsLinked to original sources
PubMedDate not supplied

Immunosuppressants.

This edition of the Med-Psych Drug-Drug Interactions Update begins a change in format. Starting with this column, each column will feature one drug-drug interaction (DDI) topic that will be explored in depth. This edition features DDIs associated with the commonly used immunosuppressants. These drugs are frequently encountered by consultation-liaison psychiatrists in tertiary care settings. Generally, most of these drugs have narrow safety and therapeutic windows; therefore, other drugs that change their serum levels can have deleterious effects. In this review, the DDI profiles of cyclosporine, tacrolimus, sirolimus, and the corticosteroids are explored.

Humans↗
PubMedDate not supplied

Triptans.

Triptans are potent serotonin (5-HT) 1B/1D receptor agonists used to abort and treat migraine headaches. Although the triptans share pharmacodynamic characteristics at 5-HT(1B/1D) receptors, they differ pharmacokinetically. This column reviews how the triptans are metabolized. Generally, the triptans are metabolized by phase I monoamine oxidases (MAOs) and by various cytochrome p450 enzymes. However, each triptan has a unique metabolic profile, leading to significant differences in each triptan's potential for drug-drug interactions. These differences are detailed in this review.

Drug Interactions↗
PubMedDate not supplied

Pharmacokinetic drug interactions of morphine, codeine, and their derivatives: theory and clinical reality, part I.

Pharmacokinetic drug-drug interactions with morphine, hydromorphone, and oxymorphone are reviewed in this column. Morphine is a naturally occurring opiate that is metabolized chiefly through glucuronidation by uridine diphosphate glucuronosyl transferase (UGT) enzymes in the liver. These enzymes produce an active analgesic metabolite and a potentially toxic metabolite. In vivo drug-drug interaction studies with morphine are few, but they do suggest that inhibition or induction of UGT enzymes could alter morphine and its metabolite levels. These interactions could change analgesic efficacy. Hydromorphone and oxymorphone, close synthetic derivatives of morphine, are also metabolized primarily by UGT enzymes. Hydromorphone may have a toxic metabolite similar to morphine. In vivo drug-drug interaction studies with hydromorphone and oxymorphone have not been done, so it is difficult to make conclusions with these drugs.

Codeine↗
PubMedDate not supplied

Six patterns of drug-drug interactions.

The literature on pharmacokinetic drug-drug interactions usually focuses on various interactions relating to the cytochrome p450 system, phase II glucuronidation, and P-glycoprotein function. However, there has been relatively little examination of how the modes or patterns that govern these interactions can be systematically characterized to better anticipate drug-drug interactions in clinical practice. This article details a schema of six core patterns of pharmacokinetic drug-drug interaction relating to processes of induction and inhibition and the action of substrates. Case examples illustrating each pattern are provided.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

Antihistamines.

Antihistamines and their drug-drug interactions are reviewed in depth. The metabolism of "classic" or sedating antihistamines is coming to light through in vivo and in vitro studies. The polymorphic CYP 2D6 metabolic enzyme appears to be potently inhibited by many of these over-the-counter medications. The history of the discontinued "second-generation" antihistamines terfenadine and astemizole is reviewed to remind the reader why the understanding of the cytochrome P450 system became increasingly important when the cardiotoxicity of these drugs became apparent. The "third-generation" nonsedating antihistamines are also listed and compared. They have been exhaustively scrutinized for drug-drug interactions and cardiotoxicity, and they appear to have no serious drug-drug interactions at recommended doses.

Astemizole↗