|
|
Caffeine Ephedra* | |
| Depletion or interference |
None known |
| Side effect reduction/prevention |
None known |
| Supportive interaction |
None known |
| Reduced drug absorption/bioavailability |
None known |
An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
Ephedra
Ephedra is the plant from which the drug ephedrine was
originally isolated. Phenylpropanolamine and ephedrine have similar effects and side
effects.1 Until 2004, ephedra, also called ma huang, was used in many herbal
products including supplements promoted for weight loss.
While interactions between phenylpropanolamine and ephedra have not been reported, it seems likely that such interactions could occur. To prevent potential problems, people taking phenylpropanolamine-containing products should avoid using ephedra/ephedrine-containing products.
Caffeine
Phenylpropanolamine can increase blood pressure,2 a danger especially in people
with high blood pressure.3 In a
double-blind study of six healthy people, administration of caffeine and phenylpropanolamine
produced an additive increase in blood pressure.4 Additionally, in a study of 16
healthy people, phenylpropanolamine plus caffeine resulted in higher serum caffeine levels
than when caffeine was given alone.5
Caffeine is found in coffee, tea, soft drinks, chocolate, guaraná (Paullinia cupana), nonprescription drugs, and supplement products containing caffeine or guaraná. People taking phenylpropanolamine-containing products can minimize the interaction with caffeine by limiting or avoiding caffeine.
1. Threlkeld DS, ed. Respiratory Drugs, Sympathomimetics. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, May 1994, 173a–3h.
2. Hoffman BB, Lefkowitz RL. Catecholamines, sympathomimetic drugs, and adrenergic receptor antagonists. In Goodman and Gilman’s The Pharmcological Basis of Therapeutics, 9th ed. New York: McGraw-Hill, 1996, 223.
3. Threlkeld DS, ed. Respiratory Drugs, Sympathomimetics. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1993, 173a–3h.
4. Brown NJ, Ryder D, Branch RA. A pharmacodynamic interaction between caffeine and phenylpropanolamine. Clin Pharmacol Ther 1991;50:363–71.
5. Lake CR, Rosenberg DB, Gallant S, et al. Phenylpropanolamine increases plasma caffeine levels. Clin Pharmacol Ther 1990;47:675–85.
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