ACTIDIL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACTIDIL (ACTIDIL).
H1-receptor antagonist; competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract, blocking histamine-induced bronchoconstriction, vasodilation, and increased capillary permeability.
| Metabolism | Hepatic via CYP450 isoenzymes (primarily CYP3A4 and CYP2D6); undergoes N-demethylation and N-oxidation. |
| Excretion | Renal excretion of unchanged drug and metabolites accounts for approximately 60-80% of the administered dose; biliary/fecal elimination comprises the remainder (20-40%). |
| Half-life | Terminal elimination half-life is approximately 20-25 hours in healthy adults; may be prolonged in elderly or patients with hepatic impairment. |
| Protein binding | Approximately 90% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | 2.5-4.0 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is approximately 50-60% due to first-pass metabolism. |
| Onset of Action | Oral: 30-60 minutes; Intramuscular: 15-30 minutes; Intravenous: 1-3 minutes. |
| Duration of Action | 4-6 hours for antihistaminic effect; clinical duration may be up to 12 hours due to active metabolites (e.g., triprolidine). |
2.5 mg orally every 4 to 6 hours as needed; maximum 10 mg per day.
| Dosage form | SYRUP |
| Renal impairment | GFR 10-50 mL/min: 2.5 mg every 6-8 hours; GFR <10 mL/min: 2.5 mg every 8-12 hours. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: contraindicated. |
| Pediatric use | Children 2-5 years: 1.25 mg orally every 4-6 hours (max 5 mg/day); Children 6-12 years: 1.25-2.5 mg every 4-6 hours (max 7.5 mg/day). |
| Geriatric use | Initiate at 1.25 mg orally every 6-8 hours; maximum 5 mg per day due to increased risk of anticholinergic effects and renal impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ACTIDIL (ACTIDIL).
| Breastfeeding | Excretion into breast milk likely but negligible amounts; no adverse effects reported in infants. M/P ratio not established. Considered compatible with breastfeeding; monitor for sedation or irritability in neonate. |
| Teratogenic Risk | First trimester: Limited human data; animal studies show no teratogenicity. Second and third trimesters: Not associated with major congenital malformations. However, anticholinergic effects may cause neonatal tachycardia, irritability, and withdrawal symptoms if used near term. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to any component","Concurrent use with monoamine oxidase inhibitors"]
| Precautions | ["May cause drowsiness and impair mental alertness","Avoid alcohol and other CNS depressants","Use with caution in patients with narrow-angle glaucoma, prostatic hypertrophy, or urinary retention","Elderly patients are more susceptible to anticholinergic effects"] |
| Food/Dietary | No specific food interactions, but taking with food may reduce GI side effects. Alcohol should be strictly avoided due to additive CNS depression. Grapefruit juice is not documented to interact. |
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| Fetal Monitoring |
| Monitor maternal blood pressure and heart rate due to anticholinergic effects. Fetal heart rate monitoring advised if used during labor. Assess neonatal for sedation, respiratory depression, or anticholinergic effects after delivery. |
| Fertility Effects | No known impact on fertility in humans. Animal studies show no impairment of fertility. |
| Clinical Pearls |
| ACTIDIL (triprolidine) is a first-generation antihistamine with sedative properties. Use cautiously in elderly due to risk of confusion, urinary retention, and falls. Avoid in patients with narrow-angle glaucoma, BPH, or asthma. Administer with food if GI upset occurs. Onset of action is 30-60 minutes; duration 4-6 hours. |
| Patient Advice | Do not drive or operate heavy machinery until you know how this medication affects you; it can cause drowsiness. · Avoid alcohol and other CNS depressants, as they may increase sedation. · Take exactly as prescribed; do not exceed recommended dose. · If you miss a dose, skip it; do not double the next dose. · Notify your doctor if you experience blurred vision, difficulty urinating, or severe drowsiness. · Do not use for prolonged periods without medical advice. |