Dorzolamide

Generic name: dorzolamide ophthalmic
Brand name: Trusopt
Dosage form: ophthalmic solution (2%; 2% preservative-free)
Drug class: Ophthalmic glaucoma agents

Medically reviewed by A Ras MD.

What is dorzolamide?

Dorzolamide is a prescription medicine that is used to treat glaucoma. It is used to lower high eye pressure.

Description

Dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP is the combination of a topical carbonic anhydrase inhibitor and a topical beta-adrenergic receptor blocking agent.

Dorzolamide hydrochloride is described chemically as: ( 4S-trans)-4- (ethylamino)- 5,6-dihydro-6-methyl- 4H-thieno[2,3- b]thiopyran-2-sulfonamide 7,7-dioxide monohydrochloride. Dorzolamide hydrochloride is optically active. The specific rotation is:

Its empirical formula is C 10 H 16 N 2 O 4 S 3 •HCl and its structural formula is:

Dorzolamide hydrochloride has a molecular weight of 360.91. It is a white to off-white, crystalline powder, which is soluble in water and slightly soluble in methanol and ethanol.

Timolol maleate is described chemically as: (-)-1-(tert-butylamino)-3-[(4- morpholino-1,2,5-thiadiazol-3-yl)oxy]-2-propanol maleate (1:1) (salt). Timolol maleate possesses an asymmetric carbon atom in its structure and is provided as the levo-isomer. The optical rotation of timolol maleate is:

Its molecular formula is C 13 H 24 N 4 O 3 S•C 4 H 4 O 4 and its structural formula is:

Timolol maleate has a molecular weight of 432.50. It is a white, odorless, crystalline powder which is soluble in water, methanol, and alcohol. Timolol maleate is stable at room temperature.

Dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP is supplied as a sterile, isotonic, buffered, slightly viscous, aqueous solution. The pH of the solution is approximately 5.65, and the osmolarity is 242-323 mOsM. Each mL of Dorzolamide hydrochloride and timolol maleate ophthalmic solution, USP contains 20 mg dorzolamide (22.26 mg of dorzolamide hydrochloride) and 5 mg timolol (6.83 mg timolol maleate). Inactive ingredients are sodium citrate, hydroxyethyl cellulose, sodium hydroxide, mannitol, and water for injection. Benzalkonium chloride 0.0075% is added as a preservative.

Mechanism of Action

Dorzolamide hydrochloride and timolol maleate ophthalmic solution is comprised of two components: dorzolamide hydrochloride and timolol maleate. Each of these two components decreases elevated intraocular pressure, whether or not associated with glaucoma, by reducing aqueous humor secretion. Elevated intraocular pressure is a major risk factor in the pathogenesis of optic nerve damage and glaucomatous visual field loss. The higher the level of intraocular pressure, the greater the likelihood of glaucomatous field loss and optic nerve damage.

Dorzolamide hydrochloride is an inhibitor of human carbonic anhydrase II. Inhibition of carbonic anhydrase in the ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport. Timolol maleate is a beta 1 and beta 2 (non-selective) adrenergic receptor blocking agent that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity. The combined effect of these two agents administered as Dorzolamide hydrochloride and timolol maleate ophthalmic solution twice daily results in additional intraocular pressure reduction compared to either component administered alone, but the reduction is not as much as when dorzolamide administered three times daily and timolol twice daily are administered concomitantly.

Before taking dorzolamide, tell your doctor:

If you are allergic to dorzolamide; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
If you have kidney disease.
If you are taking any of these drugs: Acetazolamide or methazolamide.
If you are breast-feeding or plan to breast-feed.

This is not a list of all drugs or health problems that interact with dorzolamide.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take dorzolamide with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take dorzolamide?

Tell all of your health care providers that you take dorzolamide. This includes your doctors, nurses, pharmacists, and dentists.
If you have a sulfa (sulfonamide) allergy, talk with your doctor.
Have your eye pressure and eyesight checked as you have been told by the doctor.
Use care when driving or doing other tasks that call for clear eyesight.
Tell your doctor if you have an eye infection, eye injury, or will be having eye surgery.
Bright lights may bother you. Wear sunglasses.
Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using dorzolamide while you are pregnant.

How is dorzolamide best taken?

Use dorzolamide as ordered by your doctor. Read all information given to you. Follow all instructions closely.

For the eye only.
Wash your hands before and after use.
Take out contact lenses before using dorzolamide. Lenses may be put back in 15 minutes after dorzolamide is given. Do not put contacts back in if your eyes are irritated or infected.
Do not touch the container tip to the eye, lid, or other skin.
Tilt your head back and drop drug into the eye.
If more than 1 drug is being used in the same eye, use each drug at least 5 minutes apart.

What do I do if I miss a dose?

Use a missed dose as soon as you think about it.
If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
Do not use 2 doses at the same time or extra doses.

What are the side effects of dorzolamide that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
Change in eyesight, eye pain, or very bad eye irritation.
Eye or eyelid swelling.
Rarely, very bad effects have happened with sulfa drugs. Sometimes, these have been deadly. These effects have included liver problems, blood problems, and very bad skin reactions (Stevens-Johnson syndrome/toxic epidermal necrolysis). Call your doctor right away if you have a rash; red, swollen, blistered, or peeling skin; red or irritated eyes; sores in your mouth, throat, nose, or eyes; fever, chills, or sore throat; cough that is new or worse; feeling very tired or weak; any bruising or bleeding; or signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.

What are some other side effects of dorzolamide?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

Burning.
Stinging.
Eye irritation.
Blurred eyesight.
Bad taste in your mouth.
Dry eyes.
More tears.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out dorzolamide?

Store at room temperature.
Protect from light.
Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.