HOMAPIN-10
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HOMAPIN-10 (HOMAPIN-10).
Homapin-10 is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow from the brainstem, leading to decreased peripheral vascular resistance and blood pressure.
| Metabolism | Hepatic metabolism via CYP2D6 and CYP3A4; undergoes glucuronidation. |
| Excretion | HOMAPIN-10 is primarily excreted renally as unchanged drug (70-80%), with biliary/fecal elimination accounting for 15-20% and minor metabolism 5-10%. |
| Half-life | Terminal elimination half-life is 3-5 hours in adults with normal renal function; prolonged in renal impairment (up to 20 hours in severe cases), necessitating dose adjustment. |
| Protein binding | 45-55% bound primarily to albumin; lower binding in hypoalbuminemia. |
| Volume of Distribution | 1.2-1.5 L/kg, indicating extensive distribution into tissues, with high concentrations in lungs, kidney, and liver. |
| Bioavailability | Oral: 70-85% (first-pass metabolism minimal); Intramuscular: 90-100%. |
| Onset of Action | Oral: 30-60 minutes; Intramuscular: 15-30 minutes; Intravenous: 5-15 minutes. |
| Duration of Action | Oral: 4-6 hours; Parenteral: 3-5 hours; clinical effects persist longer in hepatic or renal impairment. |
10 mg orally every 8 hours as needed for extrapyramidal symptoms; maximum 30 mg per day.
| Dosage form | TABLET |
| Renal impairment | No adjustment needed for mild to moderate impairment (GFR >30 mL/min). For severe impairment (GFR <30 mL/min), reduce dose by 50% and monitor. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: avoid use. |
| Pediatric use | For children >3 years: 0.5-2 mg orally every 8 hours as needed; maximum 6 mg/day for weight <20 kg, maximum 12 mg/day for weight 20-40 kg. |
| Geriatric use | Initiate at 5 mg orally every 8 hours; titrate slowly; monitor for anticholinergic effects and confusion. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HOMAPIN-10 (HOMAPIN-10).
| Breastfeeding | Homatropine methylbromide is a quaternary ammonium compound with limited transfer into breast milk. M/P ratio unknown; expected to be low due to ionization and high molecular weight. Not recommended in breastfeeding due to potential anticholinergic effects in the infant (tachycardia, constipation, dry mouth). If used, monitor infant for these effects. |
| Teratogenic Risk | HOMAPIN-10 (homatropine methylbromide) is an anticholinergic agent. FDA pregnancy category C: animal studies have shown adverse effects on the fetus (increased resorptions, delayed ossification) at maternally toxic doses. No adequate human studies. First trimester: limited data suggest no major malformations; however, anticholinergics may be associated with minor anomalies. Second and third trimesters: may cause fetal tachycardia, reduced gastrointestinal motility, and meconium ileus. Avoid if possible; use only if clearly needed. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to homapin or any component; severe bradycardia or heart block; pregnancy (Category C).
| Precautions | May cause sedation and dizziness; avoid abrupt discontinuation to prevent rebound hypertension; use with caution in patients with hepatic impairment, history of depression, or bradycardia. |
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| Fetal Monitoring | Monitor maternal heart rate and blood pressure due to potential anticholinergic side effects (tachycardia, hypertension). Assess for anticholinergic symptoms (blurred vision, urinary retention, constipation). In the fetus/neonate, monitor heart rate for tachycardia and gastrointestinal function for delayed meconium passage. |
| Fertility Effects | Homatropine methylbromide may impair male and female fertility by reducing libido and causing erectile dysfunction or anorgasmia due to anticholinergic effects on autonomic nervous system. Reversible upon discontinuation. No specific data on fertility in humans; animal studies show no direct reproductive toxicity at therapeutic doses. |