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Timolol is a beta-blocker drug used to lower blood pressure in people with hypertension, treat people after heart attacks, and prevent migraine headaches. Timolol is available alone and in a combination product used to lower blood pressure. Timolol is also available in eye drop and eye gel preparations used to lower high internal eye pressure due to glaucoma and other conditions.
Interactions with Dietary Supplements
Coenzyme Q10
In a group of 16 glaucoma patients treated with a timolol eye preparation, six weeks of oral
coenzyme Q10 (90 mg per day) was reported to reduce timolol-induced cardiovascular side
effects without affecting intraocular pressure treatment.1
Potassium
Some beta-adrenergic blockers (called “nonselective” beta blockers) decrease the
uptake of potassium from the blood into the cells,2 leading to excess potassium in
the blood, a potentially dangerous condition known as hyperkalemia.3 People taking
beta-blockers should therefore avoid taking potassium supplements, or eating large quantities
of fruit (e.g.,
bananas), unless directed to do so by their doctor.
Interactions with Herbs
Pleurisy root
As pleurisy root and other plants in the Aesclepius genus contain cardiac glycosides,
it is best to avoid use of pleurisy root with heart medications such as
beta-blockers.4
Interactions with Foods and Other Compounds
Food
Timolol may be taken with or without food.5
Alcohol
Timolol may cause drowsiness, dizziness, lightheadedness, or blurred vision.6
Alcohol may intensify these effects and increase the risk of accidental injury. To prevent
problems, people taking timolol should avoid alcohol.
Summary of Interactions for Timolol
| Depletion or interference | None known |
|---|---|
| Adverse interaction | None known |
| Side effect reduction/prevention | Coenzyme Q10 |
| Supportive interaction | None known |
| Reduced drug absorption/bioavailability | None known |
For the convenience of the reader, the information in the summary is categorized as follows: “Depletion or interference” indicates the drug may deplete or interfere with the absorption or function of the supplement or herb. “Adverse interaction” indicates that the supplement or herb used together with the drug may result in undesirable effects. “Side effect reduction/prevention” indicates the supplement or herb may reduce the likelihood and/or severity of a potential side effect caused by the drug. “Supportive interaction” indicates the supplement or herb may support or aid the function of the drug. “Reduced drug absorption/bioavailability” indicates that the supplement or herb may decrease the absorption and/or activity of the drug in the body. An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
References:
1. Takahashi N, Iwasaka T, Sugiura T, et al. Effect of coenzyme Q10 on hemodynamic response to ocular timolol. J Cardiovasc Pharmacol 1989;14:462–8.
2. Rosa RM, Silva P, Young JB, et al. Adrenergic modulation of extrarenal potassium disposal. N Engl J Med 1980;302:431–4.
3. Lundborg P. The effect of adrenergic blockade on potassium concentrations in different conditions. Acta Med Scand Suppl 1983;672:121–6 [review].
4. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. London: Pharmaceutical Press, 1996, 213–4.
5. Mantyla R, Mannisto P, Nykanen S, et al. Pharmacokinetic interactions of timolol with vasodilating drugs, food and phenobarbitone in healthy human volunteers. Eur J Clin Pharmacol 1983;24:227–30.
6. Threlkeld DS, ed. Diuretics and Cardiovasculars, Beta-Adrenergic Blocking Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Feb 1993, 158q.
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