BRINZOLAMIDE
Clinical safety rating: safe
Animal studies have demonstrated safety
Brinzolamide is a carbonic anhydrase inhibitor. It inhibits carbonic anhydrase II (CA-II) in the ciliary processes of the eye, reducing aqueous humor secretion and thereby lowering intraocular pressure.
| Metabolism | Primarily metabolized via hepatic cytochrome P450 isoenzymes, including CYP3A4, CYP2A6, CYP2C8, and CYP2C9, to its major metabolite N-desethylbrinzolamide. |
| Excretion | Renal: approximately 60% unchanged; biliary/fecal: minimal (<10%) |
| Half-life | Terminal elimination half-life: 111 days (due to extensive red blood cell binding); clinical context: steady-state reached after 8–12 weeks of dosing |
| Protein binding | ~60% bound to plasma proteins (primarily albumin, also carbonic anhydrase in RBCs) |
| Volume of Distribution | 0.13–0.25 L/kg (confined primarily to plasma and RBCs; low Vd due to high tissue binding) |
| Bioavailability | Ophthalmic: systemic bioavailability ~10% (via corneal absorption); oral: not clinically used |
| Onset of Action | Topical (ophthalmic): intraocular pressure reduction begins within 1–2 hours |
| Duration of Action | Topical (ophthalmic): IOP reduction lasts 12–24 hours; clinical note: twice-daily dosing recommended |
1 drop of 1% solution in the affected eye(s) twice daily.
| Dosage form | SUSPENSION/DROPS |
| Renal impairment | Contraindicated in severe renal impairment (CrCl <30 mL/min). For CrCl 30-60 mL/min, use with caution; no specific dose adjustment recommended but monitor for metabolic acidosis. |
| Liver impairment | No specific adjustment required in mild to moderate hepatic impairment (Child-Pugh A, B). Not studied in severe hepatic impairment (Child-Pugh C); use with caution. |
| Pediatric use | Safety and efficacy not established in pediatric patients (no approved dosing). |
| Geriatric use | No specific dose adjustment required; use with caution due to increased risk of corneal edema and metabolic acidosis in elderly patients. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Oral carbonic anhydrase inhibitors may have additive effects Salicylates may cause acid-base disturbances Sulfonamide hypersensitivity reactions may occur.
| Breastfeeding | Excretion in human milk unknown; M/P ratio not available. Due to potential for serious adverse reactions in nursing infants, decision should be made to discontinue nursing or drug. Consider alternative therapy. |
| Teratogenic Risk | Brinzolamide is a carbonic anhydrase inhibitor. Limited human data; animal studies show no teratogenicity at clinically relevant doses. Risk cannot be excluded. Avoid in pregnancy unless benefit outweighs risk. First trimester: potential for teratogenic effects unknown; second and third trimesters: possible fetal acidosis due to maternal carbonic anhydrase inhibition. |
■ FDA Black Box Warning
None.
| Common Effects | ocular hypertension |
| Serious Effects |
["Hypersensitivity to brinzolamide or any component of the formulation","Severe renal impairment (CrCl < 30 mL/min) or hyperchloremic acidosis due to risk of metabolic acidosis","Concomitant use with oral carbonic anhydrase inhibitors (additive systemic effects)"]
| Precautions | ["Sulfonamide allergy: can cause serious adverse reactions similar to systemic sulfonamides, including Stevens-Johnson syndrome and toxic epidermal necrolysis.","Corneal endothelial function: use with caution in patients with compromised corneas due to potential for edema.","Bacterial keratitis: risk from contaminated ophthalmic solutions.","Ocular effects: may cause blurred vision, eye discomfort, and other local reactions.","Systemic effects: possible metabolic acidosis, especially in patients with renal impairment or concurrent oral carbonic anhydrase inhibitors."] |
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| Fetal Monitoring | Monitor maternal renal function and electrolytes. Assess fetal growth and well-being with serial ultrasound. Monitor for signs of metabolic acidosis in neonate if used near term. |
| Fertility Effects | No human data on fertility effects. Animal studies showed no impairment of fertility at doses up to 2.5 mg/kg/day. Theoretical risk of sulfonamide-related spermatogenesis impairment; clinical significance unknown. |
| Food/Dietary |
| No direct food interactions. However, brinzolamide may cause metabolic acidosis, so avoid carbonic anhydrase inhibitors (e.g., acetazolamide) and limit sodium bicarbonate intake. No specific dietary restrictions. |
| Clinical Pearls | Brinzolamide is a carbonic anhydrase inhibitor used topically for ocular hypertension. It reduces intraocular pressure by decreasing aqueous humor secretion. Unlike systemic CAIs, it causes fewer systemic side effects but may still cause metabolic acidosis in susceptible patients. Avoid use in patients with sulfonamide allergy due to cross-sensitivity. Monitor corneal endothelial function in patients with compromised corneas. Shake suspension well before use. |
| Patient Advice | Shake the bottle well before each use. · Instill one drop in the affected eye(s) three times daily. · Wash hands before and after administration. · Remove contact lenses before instilling and wait 15 minutes before reinserting. · Do not touch the dropper tip to any surface. · Report any signs of allergy or severe eye discomfort. · May cause temporary blurred vision; avoid driving until clear. |