QBREXZA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for QBREXZA (QBREXZA).
Selective D1 and D5 dopamine receptor antagonist; reduces dopamine-mediated vasodilation in choroidal blood vessels, decreasing choroidal thickness and neovascularization.
| Metabolism | Primarily metabolized by CYP3A4 and CYP2D6; minor contributions from CYP1A2 and CYP2C19. |
| Excretion | Renal: approximately 30% as unchanged drug; fecal: approximately 60% as metabolites and parent compound; biliary excretion contributes to fecal elimination. |
| Half-life | Terminal elimination half-life is approximately 150 hours (range 120-200 hours), supporting once-daily dosing without significant accumulation. |
| Protein binding | Approximately 99% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 17 L (not weight-adjusted; clinical meaning: drug distributes into total body water and tissues, with extensive protein binding limiting free drug concentration). |
| Bioavailability | Topical: systemic absorption is low (approximately 0.2% of applied dose), with negligible bioavailability after topical application. |
| Onset of Action | Topical: reduction in sweating observed within 1-2 weeks of daily application. |
| Duration of Action | Duration of effect persists for 24 hours with once-daily application; continued use required to maintain efficacy. |
1 capsule (40 mg) orally twice daily with or without food.
| Dosage form | CLOTH |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (eGFR <30 mL/min/1.73 m²) or ESRD; use caution. |
| Liver impairment | No dose adjustment required for mild hepatic impairment (Child-Pugh A). Not recommended in moderate to severe hepatic impairment (Child-Pugh B or C). |
| Pediatric use | Safety and efficacy in pediatric patients (<18 years) have not been established. |
| Geriatric use | No specific dose adjustment; however, elderly patients may have increased sensitivity to anticholinergic effects. Use with caution in patients >65 years due to potential comorbidities and concomitant medications. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for QBREXZA (QBREXZA).
| Breastfeeding | Unknown if excreted in human milk; M/P ratio not available; consider benefits of breastfeeding vs potential for infant harm. |
| Teratogenic Risk | Insufficient human data; animal studies show no teratogenic effects at systemic exposures similar to human therapeutic levels, but risk cannot be excluded; first trimester: theoretical risk; second/third trimester: no known specific fetal risks. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to QBREXZA or any component","Active intraocular infection or inflammation","Uncontrolled glaucoma"]
| Precautions | ["Risk of retinal artery occlusion and retinal vein occlusion","May cause increased intraocular pressure (IOP); monitor IOP regularly","Potential for cardiovascular events (hypotension, bradycardia) due to systemic exposure","Avoid use in patients with uncontrolled hypertension or recent cardiovascular events","Potential for drug interactions with CYP3A4 and CYP2D6 inhibitors/inducers"] |
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| No specific fetal monitoring required; monitor maternal blood pressure and signs of angioedema. |
| Fertility Effects | No human data on fertility; animal studies show no impairment at clinically relevant doses. |