TRUSOPT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TRUSOPT (TRUSOPT).
Carbonic anhydrase inhibitor; decreases aqueous humor secretion by inhibiting carbonic anhydrase in the ciliary processes of the eye.
| Metabolism | Primarily metabolized via renal clearance; not extensively metabolized by the liver. |
| Excretion | Renal excretion as unchanged drug: approximately 70% of a topically applied dose is excreted renally; the remainder is eliminated via biliary/fecal routes (30%). Following oral administration, renal excretion accounts for about 65-70%. |
| Half-life | Terminal elimination half-life of dorzolamide in whole blood is approximately 4 months due to tight binding to carbonic anhydrase in red blood cells; however, the drug's clinical effect on intraocular pressure has a half-life of about 24 hours. |
| Protein binding | Approximately 33% bound to plasma proteins; primarily binds to carbonic anhydrase II in red blood cells. |
| Volume of Distribution | Vd is approximately 3.7 L/kg (based on whole blood distribution) due to extensive binding to carbonic anhydrase in red blood cells and ocular tissues. |
| Bioavailability | Systemic bioavailability after topical ophthalmic administration is approximately 2-4% of the total dose; oral bioavailability is nearly 100%. |
| Onset of Action | Ophthalmic: reduction in intraocular pressure begins within 1 hour after topical instillation. |
| Duration of Action | Duration of intraocular pressure reduction is approximately 8-12 hours after a single dose; clinically, the drug is administered three times daily to maintain effect. |
One drop of 2% solution in affected eye(s) twice daily, approximately 12 hours apart.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | For CrCl 30-60 mL/min: no adjustment needed. For CrCl <30 mL/min: use with caution; dose reduction not established but systemic accumulation possible. Contraindicated in severe renal impairment (CrCl <10 mL/min) due to risk of metabolic acidosis. |
| Liver impairment | No specific Child-Pugh based adjustments available. Use with caution in severe liver disease due to potential for increased systemic effects. |
| Pediatric use | Safety and efficacy not established in pediatric patients below 2 years. For children ≥2 years: one drop of 2% solution in affected eye(s) twice daily. |
| Geriatric use | No specific dose adjustment. Use lowest effective dose due to increased risk of systemic side effects (e.g., metabolic acidosis, taste perversion). Monitor renal function and electrolytes. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TRUSOPT (TRUSOPT).
| Breastfeeding | It is unknown if dorzolamide is excreted in human milk. M/P ratio not available. Systemic absorption after topical ocular administration is minimal, but caution should be exercised when administered to a nursing woman. |
| Teratogenic Risk | Pregnancy Category C. In animal studies, topical ocular administration of dorzolamide at doses up to 2.5 mg/kg/day (41 times the human ophthalmic dose) caused vertebral malformations in rabbits. No adequate and well-controlled studies in pregnant women. Trimester-specific risks: First trimester: potential risk based on animal data; caution advised. Second and third trimesters: unknown risk; use only if clearly needed. |
■ FDA Black Box Warning
Sulfonamide component; not for systemic use; ocular administration only.
| Serious Effects |
Hypersensitivity to any component of the product; severe renal impairment (CrCl <30 mL/min); hyperchloremic acidosis; narrow-angle glaucoma (unless adequately open after iridectomy).
| Precautions | Sulfonamide allergy cross-reactivity; corneal endothelial decompensation (especially in patients with low endothelial cell count); ocular irritation, blurred vision, and hypersensitivity reactions. |
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| Fetal Monitoring | No specific maternal or fetal monitoring required. Monitor for ocular adverse effects and systemic effects such as metabolic acidosis or sulfonamide reactions. In pregnant women, assess fetal development via standard prenatal care. |
| Fertility Effects | No human data on fertility. Animal studies: no impairment of fertility in male and female rats treated with oral dorzolamide at doses up to 19.5 mg/kg/day (321 times the human ophthalmic dose). |