HUMORSOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HUMORSOL (HUMORSOL).
Inhibits acetylcholinesterase, increasing acetylcholine concentration at cholinergic synapses, enhancing parasympathetic activity.
| Metabolism | Primarily hydrolyzed by plasma esterases. |
| Excretion | Renal: 90% as unchanged drug and metabolites; Biliary/Fecal: <10% |
| Half-life | Terminal elimination half-life: 24-48 hours; Clinically, steady-state achieved in 7-10 days |
| Protein binding | ~50% bound to albumin |
| Volume of Distribution | 0.5-1.0 L/kg; Concentrates in aqueous humor and ciliary body |
| Bioavailability | Topical ophthalmic: <10% due to corneal barrier; Intraocular: 100% |
| Onset of Action | Intraocular injection: 1-2 hours; Topical ophthalmic: 30 minutes |
| Duration of Action | Intraocular injection: 24-48 hours; Topical ophthalmic: 6-8 hours; Duration depends on dose and route |
1-2 drops of 0.25% solution in the affected eye(s) twice daily, approximately 12 hours apart.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dose adjustment required for renal impairment. Data insufficient for GFR-based modifications. |
| Liver impairment | No dose adjustment required for hepatic impairment. Child-Pugh based modifications not established. |
| Pediatric use | Use same concentration as adults; 1 drop in affected eye(s) twice daily. Not studied in infants under 1 year. |
| Geriatric use | No specific dose adjustment; use same adult dosing. Monitor for increased systemic absorption due to age-related ocular surface changes. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HUMORSOL (HUMORSOL).
| Breastfeeding | No data on M/P ratio. Timolol (active metabolite) is excreted in breast milk in low concentrations; estimated infant dose <2% of maternal weight-adjusted dose. Considered compatible with breastfeeding by the American Academy of Pediatrics. Monitor infant for signs of beta-blockade (bradycardia, hypoglycemia). |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: Animal studies have shown teratogenic effects (skeletal abnormalities, cleft palate) at doses 10 times the human dose. No adequate human studies; potential fetal risk cannot be ruled out. Second and third trimesters: Not associated with major structural anomalies, but may cause transient neonatal effects such as bradycardia, hypotension, and respiratory depression if used near term. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to echothiophate or any component","Active uveitis","Angle-closure glaucoma before iridectomy"]
| Precautions | Risk of retinal detachment; use with caution in patients with history of retinal detachment, asthma, or peptic ulcer; may cause systemic cholinergic effects. |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of bronchospasm. For fetus: serial ultrasound to monitor growth; fetal heart rate monitoring if maternal bradycardia occurs. Neonates should be observed for bradycardia, hypoglycemia, and respiratory distress for 48 hours after delivery. |
| Fertility Effects | No known impairment of fertility in animal studies. In humans, no evidence of adverse effects on spermatogenesis or ovulation. Beta-blockers may mask signs of hypoglycemia, which could rarely affect reproductive function. |