Episode 113: How to interact with drug interactions

In episode 113, Mike and James interact in a mainly positive way about what to do with the 1000s of drug interactions that are out there. They talk about the concepts of pharmacokinetic and pharmacodynamic interactions and outline which ones appear to be clinically important. At the end they realise that all of their interactions over the last 113 podcasts episodes have been clinically irrelevant and vow to interact much more usefully in the future.

Show notes

1) Hospitalizations due to interactions

BMJ 2004;329:15–19

2) Plasma-protein binding interactions – they are not clinically important

Br J Clin Pharmacol 1994;37:125-8

3) Key Players in Metabolism Drug Interactions

Inhibitors

fluvoxamine

gemfibrozil

fluconazole

omeprazole

paroxetine

fluoxetine

clarithromycin

Inducers

Rifampin

carbamazepine

4) What drug interactions are clinically important?

J Am Pharm Assoc 2004;44:142–151

THE MAIN ONES (DRUG affected – DRUG interacting)

Warfarin – Thyroid, NSAIDs, cimetidine, fibric acid, barbiturates, sulfinpyrazone

Benzodiazepines – Azoles

Carbamazepine – Propoxyphene, macrolides

Cyclosporine  – Rifampin

Dextromethorphan – MAOIs

Digoxin – Clarithromycin

Ergots  – Macrolides

Ganciclovir – Zidovudine

MAOIs – Sympathomimetics

Meperidine – MAOIs

Methotrexate – Trimethoprim

Nitrates – Sildenafil

Pimozide – Macrolides, azoles

SSRIs  – MAOIs

Theophylline – Quinolones, fluvoxamine

5) Oral contraceptives and antibiotic interactions – a myth?

J Am Acad Dermatol 2002;46:917-23

6) Drug interaction websites/tools

http://www.drugs.com/drug_interactions.php

http://www.rxfiles.ca/rxfiles/uploads/documents/members/cht-herbal-di.pdf

iPhone apps – Medscape, Epocrates