Prescription eye drops caused abnormal heart rate

Q. In May 2001, I suddenly developed an irregular heart rate. It would sometimes go two or three beats and then miss one. At times, my heart rate was only 41 beats per minute. During the summer, I contacted my family physician, who ordered some tests. It took until October 2003 for the mystery to be solved, and it wasn't my physician who discovered the problem. My drug company changed my glaucoma eye-drop medication from latanoprost to travoprost.

I didn't know that some glaucoma eye drops could affect the heart, but my family physician should have. Some of these medications are beta-blockers, similar to those used to treat hypertension. Timolol maleate is one of them, and the latanoprost, which caused my irregular heart rate, is a prostaglandin analog drug. These are quite effective, and many people use them without any heart problems.

When anyone starts a new drug, he or she should write down the date as well as any strange side effects. Rare side effects are quite important if you are that one rare person affected.

A. Glaucoma is often treated with beta-blocker eye drops because the condition is essentially hypertension of the eyeball. It should be treated by an ophthalmologist and monitored closely, since it can cause permanent changes to vision or even blindness.

You say you were changed from latanoprost (a prostaglandin analog) to travoprost (a synthetic prostaglandin analog). After this change you indicate your symptoms disappeared. But you then mention a third medication, timolol maleate (a nonselective beta-adrenergic receptor blocking agent) as causing heart symptoms.

In my experience, if one class of drugs causes side effects, others in that class will, too. This is not always the case, but more often than not, I have found it to hold true for my patients. A situation I believe to be more likely is that the timolol-causing side effects ceased when the medication was changed to travoprost or latanoprost.

Other than this confusion, you make an excellent point. It is important to know what medications are being taken, what the dosage is, and the date they were started. Any changes, either in medication or dosage, should also be noted, along with the date of the change. If side effects occur, this may make it easier to identify the culprit. I say may only because some people will suddenly develop adverse reactions to a medication they have been taking for many years without previous problems.

Because there are so many medications, and frequently, many disorders have several classes of drugs with several medicines within each class, it is difficult for a physician to be familiar with all the side effects. This is not an excuse but a reality. This is why, when first filling a prescription, the pharmacist includes an informational packet identifying what the medication is used for, how it is taken and what the potential side effects are.

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