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Dorzolamide – Uses, Dosage, Side Effects, Interactions

Dorzolamide is an inhibitor of carbonic anhydrase, a zinc-containing enzyme that catalyzes the rapid conversion of carbon dioxide and water into carbonic acid, protons, and bicarbonate ions. Distributed throughout many cells and tissues, various carbonic anhydrases play important roles in mineral and metabolic homeostasis. (NCI04)

Dorzolamide is 5,6-Dihydro-4H-thieno[2,3-b]thiopyran-2-sulfonamide 7,7-dioxide in which hydrogens at the 4 and 6 positions are substituted by ethylamino and methyl groups, respectively (4S, trans-configuration). A carbonic anhydrase inhibitor, it is used as the hydrochloride in ophthalmic solutions to lower increased intraocular pressure in the treatment of open-angle glaucoma and ocular hypertension. It has a role as an EC 4.2.1.1 (carbonic anhydrase) inhibitor, an antihypertensive agent, and an antiglaucoma drug. It is a sulfonamide and a member of thiophenes.

Dorzolamide is a non-bacteriostatic sulfonamide derivative and topical carbonic anhydrase (CA) inhibitor that treats elevated intraocular pressure (IOP) associated with open-angle glaucoma and ocular hypertension. It works by blocking an enzyme in the ciliary process that regulates ion balance and fluid pressure in the eyes. Unlike oral CA inhibitors, dorzolamide has negligible effects of acid-base or electrolyte disturbances and other systemic adverse effects. First marketed in 1995, dorzolamide is available in ophthalmic solutions as monotherapy marketed as Trusopt or in combination with [timolol] as Cosopt PF.

Mechanism of Action

Elevated intraocular pressure is a characteristic manifestation of ocular hypertension or open-angle glaucoma. The level of intraocular pressure (IOP) is governed by the balance between the production of aqueous humor (by ocular ciliary processes) and its outflow from the anterior segment of the eye via trabecular (conventional) or uveoscleral (unconventional) pathways. When there is an increase in the resistance to the trabecular outflow of aqueous humor, the intraocular pressure is elevated. Subsequently, optic nerve damage can occur from blood flow restrictions and mechanical distortion of ocular structures. Optic nerve damage can further result in optic disc cupping and progressive visual field loss (and blindness in some cases).[A1304] Carbonic anhydrase (CA) is a ubiquitous enzyme that catalyzes the reversible hydration of carbon dioxide to bicarbonate ions and dehydration of carbonic acid.[A1304, L11377] In the ocular ciliary processes, the local production of bicarbonate by CAs promotes sodium and fluid transport. CA-II is a key isoenzyme found primarily in red blood cells (RBCs) that regulates aqueous humor production.[A1304] Dorzolamide is a highly specific CA-II inhibitor, where it displays a 4000-fold higher affinity for carbonic anhydrase II than carbonic anhydrase I.[A1304] The inhibition of CA-II in the ciliary process disrupts the formation of bicarbonate ions and reduces sodium and fluid transport, which leads to decreased aqueous humor secretion and reduced intraocular pressure.[A1304, L11377]

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Indications of Dorzolamide

Dorzolamide is indicated for the management of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma.[L11377] It can also be used in combination with [timolol] for the same indication in patients who are insufficiently responsive to ophthalmic beta-blockers.[L11380] Its pre-operative use was also investigated to prevent elevated intraocular pressure after neodymium yttrium aluminum garnet laser posterior capsulotomy.
Intraocular Hypertension
Glaucoma, Open-Angle
Treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma

Contraindications Of Dorzolamide

Hyperchloremic acidosis
Hypokalemia (low blood potassium)
Hyponatremia (low blood sodium)
Adrenal insufficiency
Impaired kidney function
Hypersensitivity to acetazolamide or other sulfonamides.
Marked liver disease or impairment of liver function, including cirrhosis because of the risk of development of hepatic encephalopathy. Acetazolamide decreases ammonia clearance
type 1 diabetes mellitus
a condition where the adrenal glands produce less hormones called Addison’s disease
a type of joint disorder due to excess uric acid in the blood called gout
respiratory acidosis, an acid-base disorder
a blood disorder
decreased lung function
liver problems
severe liver disease
renal tubular acidosis
recurrent calcium-containing kidney stones
decreased kidney function
hyperchloremic acidosis

Dosage of Dorzolamide

Strengths: 2%; 2% preservative-free

Intraocular Hypertension

One drop in the affected eye(s) three times a day

Glaucoma (Open Angle)

One drop in the affected eye(s) three times a day

Pediatric Dose for Intraocular Hypertension

Safety and effectiveness have been demonstrated in pediatric patients in a 3-month, multicenter, double-masked, active-treatment-controlled trial:
One drop in the affected eye(s) three times a day.

Side Effects of Dorzolamide

The Most Common

Burning, stinging, or discomfort when the medicine is applied
itching, redness, swelling, or other sign of eye or eyelid irritation
Burning, dry, or itching eyes
discharge from the eye
excessive tearing
redness, pain, or swelling of the eye, eyelid, or inner lining of the eyelid
Blood in the urine
blurred vision
nausea or vomiting
pain in the side, back, or abdomen
skin rash
tearing

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Common

Blistering, burning, crusting, dryness, or flaking of the skin
change in vision
chills
cough
diarrhea
difficult or labored breathing
flashes of light
floaters in vision
hives or welts
itching skin
joint or muscle pain
large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
noisy breathing
redness of the skin
sore throat
sores, ulcers, or white spots in the mouth or on the lips
tightness in the chest
unusual tiredness or weakness

Rare

Confusion
irregular heartbeat
muscle cramps or pain
numbness, tingling, pain, or weakness in the hands or feet
seizures
trembling
weakness and heaviness of the legs

Drug Interactions of Dorzolamide

acetazolamide
aspirin
bismuth subsalicylate
choline salicylate
dichlorphenamide
diflunisal
magnesium salicylate
methazolamide
salsalate
sodium salicylate
sodium thiosalicylate
topiramate
zonisamide

Pregnancy Category

US FDA Pregnancy Category – C

Pregnancy

There are no adequate and well-controlled studies in pregnant women with Dorzolamide hydrochloride ophthalmic solution. Dorzolamide caused fetal vertebral malformations when administered orally to rabbits at 2.5 mg/kg/day (37 times the clinical exposure). Dorzolamide administered during the period of organogenesis was not teratogenic in rabbits dosed up to 1 mg/kg/day (15 times the clinical exposure). Dorzolamide hydrochloride administered orally to rats during late gestation and lactation caused growth delays in offspring at 7.5 mg/kg/day (52 times the clinical exposure). Growth was not delayed at 1 mg/kg/day (8.0 times the clinical exposure).

Lactation

There are no data on the presence of Dorzolamide hydrochloride ophthalmic solution in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Dorzolamide hydrochloride ophthalmic solution and any potential adverse effects on the breast-fed child from Dorzolamide hydrochloride ophthalmic solution. Dorzolamide is present in the milk of lactating rats (see Data).

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References