PBZ-SR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PBZ-SR (PBZ-SR).
Antihistamine; H1-receptor antagonist that competes with histamine for binding at H1 receptor sites, thereby preventing histamine-mediated allergic responses.
| Metabolism | Hepatic metabolism via hydroxylation and glucuronide conjugation; major metabolites include triprolidine metabolites. |
| Excretion | Primarily renal excretion (80-90% as unchanged drug) via glomerular filtration and tubular secretion. Biliary/fecal excretion accounts for approximately 5-10%. |
| Half-life | Terminal elimination half-life is approximately 4-6 hours in adults with normal renal function; clinically relevant dosing every 4-6 hours is recommended. |
| Protein binding | Approximately 85-90% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is 1.0-2.0 L/kg, indicating extensive tissue penetration and distribution into total body water. |
| Bioavailability | Oral bioavailability is 25-35% due to first-pass hepatic metabolism; intravenous and intramuscular routes provide complete bioavailability (100%). |
| Onset of Action | Oral: 30-60 minutes; Intramuscular: 10-20 minutes; Intravenous: 1-5 minutes. |
| Duration of Action | Duration of action is 4-6 hours for oral and intramuscular routes; intravenous duration may be slightly shorter at 3-4 hours due to rapid redistribution. |
100-200 mg orally every 12 hours; maximum 400 mg/day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 30-50 mL/min: reduce dose by 50%; GFR <30 mL/min: not recommended. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: not recommended. |
| Pediatric use | 2-5 mg/kg/day divided every 12 hours; maximum 200 mg/day. |
| Geriatric use | Start at 50 mg twice daily; titrate cautiously due to increased anticholinergic sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PBZ-SR (PBZ-SR).
| Breastfeeding | Tripelennamine is excreted into human breast milk; M/P ratio not reported. Concentrations are likely low but may cause irritability or drowsiness in the nursing infant. Use with caution, especially in preterm infants or those with respiratory instability. Alternatives with more safety data preferred. |
| Teratogenic Risk | Tripelennamine, the active ingredient in PBZ-SR, is an H1 antihistamine. Animal studies have not demonstrated teratogenic effects. Human data: limited case reports show no consistent pattern of major malformations. First trimester: theoretical risk, but data insufficient to establish safety. Second and third trimesters: no known fetal risks; however, use near term may cause neonatal irritability or respiratory depression. Overall, tripelennamine is considered low risk but should be used only if clearly needed. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Newborn or premature infants","Nursing mothers (may cause CNS depression in infants)","Hypersensitivity to triprolidine or any component","Concurrent use with MAO inhibitors"]
| Precautions | ["Sedation and CNS depression; avoid driving or operating machinery.","Concurrent use with CNS depressants may enhance sedation.","Use with caution in patients with glaucoma, prostatic hyperplasia, urinary retention, or asthma.","Elderly patients may be more sensitive to anticholinergic effects and sedation."] |
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| Fetal Monitoring | No specific maternal-fetal monitoring required beyond routine prenatal care. Observe for maternal sedation or hypotension. In neonates exposed near term, monitor for respiratory depression, irritability, or feeding difficulties. |
| Fertility Effects | No known adverse effects on human fertility reported in animal or human studies. Tripelennamine does not alter hormonal profiles or interfere with conception based on limited data. |