Although only scanty pharmacokinetic information is found for ephedrine, there are no indications that this drug, which has been on the market for several decades, is an inducer or mechanism-based inhibitor of any CYP enzymes. Continuous attention to ensure a sufficient carbohydrate intake is recommended.

Phenethylamine

Ephedrine is a sympathomimetic amine with direct and indirect actions on the adrenergic receptor system. Ephedrine is commonly used as a stimulant, appetite suppressant, concentration aid, decongestant and to treat hypotension associated with anaesthesia. It is administered orally or intravenously. Side effects such as nausea, vomiting and reduced appetite may be potentially porphyrinogenic through reduction in caloric intake.

After oral or parenteral administration, up to 77% of ephedrine is excreted in unchanged form in the urine. Half-life of elimination is about 3 to 6 hours depending on the urine pH. A smaller portion of the drug is demethylated and deaminated to hippuric acid. (Limberger 2013, SPC, Wilkinson 1968a, 1968b) Books (1977) found ephedrine to increase the clearance of dexamethasone by 42%, and increase half-life by 36 %, but the mechanism for this effect is uncertain. Ephedrine is not listed as an inducer or inhibitor of CYP enzymes. Similar substances are neither found to, nor expected to have the capacity to significantly induce or inhibit CYP enzymes (Pelkonen 2008, Preissner 2010, FDA).

Uneventful use reported in 1 patient with acute porphyria.