Timolol is a type of adrenergic blocker. It does not work as a local anesthetic, nor does it stabilize the membrane. Rather, it is topically applied to the eye to help lower intraocular pressure by stopping the eye from producing more aqueous humor. Timolol is not a miotic, which means that it has almost no effect on the size of the pupil.

Usually, the effects are noticed some 30 minutes after applying a single drop of Timolol. The maximum effect happens between one and three hours after that. The lowered pressure can be maintained for around 24 hours. It should be noted that if it is used for prolonged periods of time, Timolol can start to cause beta-blocking in other parts of the body. This means that it can cause hypotension, bradycardia, and increased airway resistance.

Timolol has only been used occasionally in children, and never longer than for twelve weeks. There has been a small clinical trial on the effects of Timolol in pediatric patients. This demonstrated that the drug can be effective as a short term treatment for primary juvenile glaucoma and primary congenital glaucoma.

How Timolol Drops Are Used

Timolol has been develop to lower ocular hypertension (increased pressure in the eye), as well as for open-angle glaucoma. Doctors may prescribe the drug for other conditions as well. The drops act as a beta-blocker, lowering fluid production and thereby pressure within the eye.

Timolol is not suitable for patients who:

• Are allergic to any of the drug’s ingredients.
• Have COPD (chronic obstructive pulmonary disease), or asthma (past and present).
• Have an unusually slow heartbeat, heart failure, or heart block.
• Have severe heart problems that have sent them into shock.
• Currently use a different beta-blocker on the eyes, such as betaxolol.

Before You Use Timolol

There are a number of conditions that are known to have interactions with Timolol drops. Hence, you must tell your physician and pharmacist about any underlying medical conditions you may have. As such, tell them if you:

• Are trying to conceive, pregnant, or nursing.
• Take any medication, be that prescription, over the counter, herbal, or supplemental.
• Have any known allergies to any substance.
• Have a history of pulmonary problems.
• Have an eye injury or infection, a drooping eyelid, double vision, or narrow-angle glaucoma.

There are also a number of medications that are known to interact with Timolol. While you should always tell your health care provider about any medication you take, this is particularly important if you currently take:

• Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, reserpine, ketanserin, digoxin, and cimetidine; certain antiarrhythmics such as quinidine, flecainide, and disopyramide; and calcium channel blockers such as verapamil, and bupivacaine. These drugs can lead to low blood pressure and to heart problems, including slow heartbeat, heart failure, and conduction problems.
• Clonidine, as this could elevate your blood pressure.
• Oral antidiabetics or insulin, as this would increase the chance of slow heart rate or low blood sugar.
• Alpha blockers, other beta blocker eye drops, or oral beta blockers, as these would increase the chance of experiencing side effects.
• Sympathomimetics, such as salmeterol or albuterol, theophylline, or epinephrine, as they may become less effective.

How to Use Timolol

Your doctor will provide you with full instructions on how to use the drops. Make sure you also read the label so that you know the dosage, and read the leaflet included with your medicine. Speak to the pharmacist should you have further questions. Before you use the drops, you should remove your contact lenses and not replace them for at least 15 minutes after applying the drops. If you take any other medication, make sure there is at least 10 minutes between using the different drugs.

To use Timolol:

• Thoroughly wash your hands with soap and water.
• Pull down the lower eyelid to create a pocket.
• Drop the medicine into the pocket, making sure that the dropper tip does not touch the eye.
• Close your eyes and apply pressure to the inside corner using your finger for about two minutes. Be careful not to blink.
• Use a clean tissue to remove excess medicine, without touching the eye.
• Try to use Timolol at the same time every day.
• Complete the entire course as prescribed.
• Do not double dose. If you forget one dose, take it as soon as possible, unless it is close to the time of your next application.

Important Safety Information

• Be aware of the side effects (more on that later).
• Do not receive any surgery, emergency care, or dental care without telling the appropriate physician that you use Timolol.
• Be aware that the medication can mask the signs of low blood sugar, which is important if you are diabetic.

Timolol Side Effects

It is quite common for medication, including Timolol, to cause side effects. Most people, however, experience very few side effects with Timolol. The table below highlights some of the common, minor, and major side effects to be aware of. If your side effects are persistent or they become bothersome, you should speak to your physician.

Health care professionals look out for specific side effects, which can tell them whether or not there are any issues with the medication. The table below highlights some of the things that they look for.

Resources and References:

Glaucoma Research Foundation – Glaucoma Medications and Their Side Effects (Glaucoma.org)

Patient – Timolol Eye Drops for Glaucoma (Timoptol, Tiopex) (Patient.info)