Medications and Drugs
Pharmacy Author: Annette O. Gbemudu, PharmD, MBA
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: timolol
BRAND NAME: Blocadren, Timolide 10-25 (These brands are no longer available
in the U.S.)
DRUG CLASS AND MECHANISM: Timolol is a beta-adrenergic blocking drug that is
used to treat high blood pressure, angina (heart pain),
heart attacks and to
prevent migraine headaches. Timolol is a first generation beta blocker in a
class that includes propranolol (Inderal, InnoPran), nadolol (Corgard),
penbutolol sulfate (Levatol), sotalol hydrochloride (Betapace), and pindolol
(Visken). They differ from other beta blockers because they are non-selective in
nature, meaning that they block both beta-1 and beta-2 receptors on nerves and,
therefore, will affect not only the heart but also the kidneys, lungs,
gastrointestinal tract, liver, uterus, muscles surrounding blood vessels, and
skeletal muscle. As a result, they could cause such effects as reduced pumping
of blood by the heart and reduced kidney function among other actions. Timolol
specifically works by blocking the stimulating actions of the sympathetic
nervous system thereby allowing the heart to relax and beat more slowly. This
reduces the amount of blood that the heart must pump. Timolol was approved by
the FDA in November 1981.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets: 5, 10, and 20 mg.
STORAGE: Timolol should be stored at room temperature, 15-30 C (59-86 F) and
kept in a tightly sealed container protected from light
PRESCRIBED FOR: Timolol is prescribed to lower blood pressure in patients
with high blood pressure (hypertension). It also is used to reduce angina (heart
pain), and to stabilize irregular heartbeats (arrhythmias) and prevent migraine
headaches. Off label uses include the treatment of hypertrophic cardiomyopathy
and mitral valve prolapse.
DOSING: The range of dosing for adults is 10 to 60 mg mg per day.
DRUG INTERACTIONS: The concurrent use of timolol and clonidine (Catapres),
may cause rebound hypertension upon abrupt discontinuation of clonidine. It is
advisable, therefore, to stop the beta adrenergic blocking drug by several days
before gradually withdrawing clonidine. Fenoldopam (Corlopam), which is used for
the treatment of severe hypertension should not be taken together with timolol
as the combination may increase the risk of hypotension due to additive effects
of the two drugs in lowering blood pressure.
Close observation should be carried out when timolol is administered to
patients receiving catecholamine-depleting drugs such as
reserpine (Harmonyl)
because of possible additive effects and the production of
hypotension and/or a
markedly slow heartbeat, which may produce
dizziness, syncope, or
postural
hypotension (dizziness upon standing). Concurrent use of
NSAIDs with timolol may
cause the antihypertensive action of beta-blockers to be decreased. This occurs
because prostaglandins are important in controlling blood pressure.
PREGNANCY: There are no adequate studies in pregnant women. Timolol should be
used during pregnancy only if the potential benefit justifies the potential
risk.
NURSING MOTHERS: Timolol has been detected in
human milk and has a potential
for adverse events in infants.
SIDE EFFECTS: Minor side effects of timolol include abdominal cramps,
diarrhea, constipation, fatigue, insomnia, nausea, and vomiting. Major side
effects include depression, vivid dreams or memory loss, fever, impotence,
lightheadedness, slow heart rate or low blood pressure, numbness, tingling,
cramps, blueness of the hands or feet, sore throat, and shortness of breath or
wheezing.
Reference: FDA Prescribing Information
Last Editorial Review: 7/31/2009
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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