DORZOLAMIDE HYDROCHLORIDE- dorzolamide hydrochloride_solution/ drops

Carbonic anhydrase (CA) is an enzyme found in many tissues of the body including the eye. It catalyzes the reversible reaction involving the hydration of carbon dioxide and the dehydration of carbonic acid. In humans, carbonic anhydrase exists as a number of isoenzymes, the most active being carbonic anhydrase II (CA-II), found primarily in red blood cells (RBCs), but also in other tissues. 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. The result is a reduction in intraocular pressure (IOP). Dorzolamide hydrochloride ophthalmic solution contains dorzolamide hydrochloride, an inhibitor of human carbonic anhydrase II. Following topical ocular administration, dorzolamide hydrochloride reduces elevated intraocular pressure. Elevated intraocular pressure is a major risk factor in the pathogenesis of optic nerve damage and glaucomatous visual field loss. When topically applied, dorzolamide reaches the systemic circulation. To assess the potential for systemic carbonic anhydrase inhibition following topical administration, drug and metabolite concentrations in RBCs and plasma and carbonic anhydrase inhibition in RBCs were measured. Dorzolamide accumulates in RBCs during chronic dosing as a result of binding to CA-II. The parent drug forms a single N-desethyl metabolite, which inhibits CA-II less potently than the parent drug but also inhibits CA-I. The metabolite also accumulates in RBCs where it binds primarily to CA-I. Plasma concentrations of dorzolamide and metabolite are generally below the assay limit of quantitation (15nM). Dorzolamide binds moderately to plasma proteins (approximately 33%). Dorzolamide is primarily excreted unchanged in the urine; the metabolite also is excreted in urine. After dosing is stopped, dorzolamide washes out of RBCs nonlinearly, resulting in a rapid decline of drug concentration initially, followed by a slower elimination phase with a half-life of about four months. To simulate the systemic exposure after long-term topical ocular administration, dorzolamide was given orally to eight healthy subjects for up to 20 weeks. The oral dose of 2 mg twice daily closely approximates the amount of drug delivered by topical ocular administration of dorzolamide 2% three times daily. Steady state was reached within 8 weeks. The inhibition of CA-II and total carbonic anhydrase activities was below the degree of inhibition anticipated to be necessary for a pharmacological effect on renal function and respiration in healthy individuals.

Dorzolamide hydrochloride ophthalmic solution is indicated in the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma. Dorzolamide hydrochloride ophthalmic solution is a carbonic anhydrase inhibitor indicated for the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma.

The dose is one drop of dorzolamide hydrochloride ophthalmic solution in the affected eye(s) three times daily. Dorzolamide hydrochloride may be used concomitantly with other topical ophthalmic drug products to lower intraocular pressure. If more than one topical ophthalmic drug is being used, the drugs should be administered at least five minutes apart. Dorzolamide hydrochloride ophthalmic solution may be used concomitantly with other topical ophthalmic drug products to lower intraocular pressure.

ADVERSE REACTIONS
The most frequently reported adverse reactions associated with dorzolamide hydrochloride ophthalmic solution were ocular burning, stinging, or discomfort immediately following ocular administration (approximately one-third of patients). Approximately one-quarter of patients noted a bitter taste following administration. Superficial punctate keratitis occurred in 10 to 15% of patients and signs and symptoms of ocular allergic reaction in approximately 10%. (6) To report SUSPECTED ADVERSE REACTIONS, contact Akorn Operating Company LLC at 1-800-932-5676 or FDA at 1-800-FDA-1088 or www. gov/medwatch Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Controlled clinical trials: see Warnings and Precautions (5. 4) In a 3-month, double-masked, active-treatment-controlled, multicenter study in pediatric patients, the adverse reactions profile of dorzolamide hydrochloride ophthalmic solution was comparable to that seen in adult patients. The following adverse reactions have been identified during post-approval use of dorzolamide hydrochloride ophthalmic solution. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure: signs and symptoms of systemic allergic reactions including angioedema, bronchospasm, pruritus, and urticaria; Stevens-Johnson syndrome and toxic epidermal necrolysis; dizziness, paresthesia; ocular pain, transient myopia, choroidal detachment following filtration surgery, eyelid crusting; dyspnea; contact dermatitis, epistaxis, dry mouth and throat irritation.
Sulfonamide Reactions
Dorzolamide hydrochloride ophthalmic solution is a sulfonamide and although administered topically is absorbed systemically. Therefore the same types of adverse reactions that are attributable to sulfonamides may occur with topical administration. Advise patients that if serious or unusual reactions including severe skin reactions or signs of hypersensitivity occur, they should discontinue the use of the product [ see Warnings and Precautions (5.1)

Dorzolamide hydrochloride ophthalmic solution is contraindicated in patients who are hypersensitive to any component of this product [ see Warnings and Precautions (5. 1) Dorzolamide hydrochloride ophthalmic solution is contraindicated in patients who are hypersensitive to any component of this product.

Risk Summary 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). The background risk of major birth defects and miscarriage for the indicated population is unknown. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Data Animal Data Developmental toxicity studies were conducted in pregnant rabbits administered dorzolamide hydrochloride orally during the period of organogenesis from gestation days 6 through 18 at doses of 0. 5, 5, and 10 mg/kg/day. The developmental lowest observed adverse effect level (LOAEL) was 2. 5 mg/kg/day, based on vertebral malformations and decreased fetal body weight. The maternal LOAEL was 2. 5 mg/kg/day, based on metabolic acidosis and reduced weight gain. The maternal and developmental no adverse effect levels (NOAELs) were 1 mg/kg/day. The rabbit doses of 1 and 2. 5 mg/kg/day represent estimated plasma C max Dorzolamide hydrochloride was administered orally to rats during late gestation and lactation (gestation day 17 through postpartum day 20) at doses of 0. 5 mg/kg/day. The developmental LOAEL was 7. 5 mg/kg/day, based on reduced birth weight, reduced weight gain, and a slight delay in postnatal development (incisor eruption, vaginal canalization and eye openings) secondary to lower offspring body weight. 5 mg/kg/day dose represents an estimated plasma C max max Risk Summary 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) Data Animal Data Lactating rats were dosed orally with 7. 5 mg/kg/day of dorzolamide hydrochloride; dorzolamide and the N-desethyl metabolite were detected in the milk. Safety and effectiveness of dorzolamide hydrochloride ophthalmic solution have been demonstrated in pediatric patients in a 3-month, multicenter, double-masked, active-treatment-controlled trial. No overall differences in safety or effectiveness have been observed between elderly and younger patients. Dorzolamide has not been studied in patients with severe renal impairment (CrCl < 30 mL/min). Because dorzolamide and its metabolite are excreted predominantly by the kidney, dorzolamide hydrochloride ophthalmic solution is not recommended in such patients. Dorzolamide has not been studied in patients with hepatic impairment and should therefore be used with caution in such patients.

Potential additive effect of oral carbonic anhydrase inhibitor with dorzolamide hydrochloride ophthalmic solution. 1) Potential acid-base and electrolyte disturbances. 2) There is a potential for an additive effect on the known systemic effects of carbonic anhydrase inhibition in patients receiving an oral carbonic anhydrase inhibitor and dorzolamide hydrochloride ophthalmic solution. The concomitant administration of dorzolamide hydrochloride ophthalmic solution and oral carbonic anhydrase inhibitors is not recommended. Although acid-base and electrolyte disturbances were not reported in the clinical trials with dorzolamide hydrochloride ophthalmic solution, these disturbances have been reported with oral carbonic anhydrase inhibitors and have, in some instances, resulted in drug interactions (e. , toxicity associated with high-dose salicylate therapy). Therefore, the potential for such drug interactions should be considered in patients receiving dorzolamide hydrochloride ophthalmic solution.

OVERDOSAGE
Electrolyte imbalance, development of an acidotic state, and possible central nervous system effects may occur. Serum electrolyte levels (particularly potassium) and blood pH levels should be monitored.
NONCLINICAL TOXICOLOGY
In a two-year study of dorzolamide hydrochloride administered orally to male and female Sprague-Dawley rats, urinary bladder papillomas were seen in male rats in the highest dosage group of 20 mg/kg/day. Papillomas were not seen in rats given oral doses of 1 mg/kg/day. These doses represent estimated plasma C max No treatment-related tumors were seen in a 21-month study in female and male mice given oral doses up to 75 mg/kg/day. This dose represents an estimated plasma C max The increased incidence of urinary bladder papillomas seen in the high-dose male rats is a class-effect of carbonic anhydrase inhibitors in rats. Rats are particularly prone to developing papillomas in response to foreign bodies, compounds causing crystalluria, and diverse sodium salts. No changes in bladder urothelium were seen in dogs given oral dorzolamide hydrochloride for one year at 2 mg/kg/day or monkeys dosed topically to the eye for one year. An oral dose of 2 mg/kg/day in dogs represents an estimated plasma C max The following tests for mutagenic potential were negative: (1) in vivo in vitro In reproduction studies of dorzolamide hydrochloride in rats, there were no adverse effects on the reproductive capacity of males or females at doses of 15 and 7.5 mg/kg/day, respectively. These doses represent estimated plasma C max
CLINICAL STUDIES
The efficacy of dorzolamide hydrochloride ophthalmic solution was demonstrated in clinical studies in the treatment of elevated intraocular pressure in patients with glaucoma or ocular hypertension (baseline IOP >= 23 mmHg). The IOP-lowering effect of dorzolamide hydrochloride ophthalmic solution was approximately 3 to 5 mmHg throughout the day and this was consistent in clinical studies of up to one year duration. The efficacy of dorzolamide hydrochloride ophthalmic solution when dosed less frequently than three times a day (alone or in combination with other products) has not been established. In a one year clinical study, the effect of dorzolamide hydrochloride ophthalmic solution 2% three times daily on the corneal endothelium was compared to that of betaxolol ophthalmic solution twice daily and timolol maleate ophthalmic solution 0.5% twice daily. There were no statistically significant differences between groups in corneal endothelial cell counts or in corneal thickness measurements. There was a mean loss of approximately 4% in the endothelial cell counts for each group over the one year period.

Golden State Medical Supply, Inc.

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