PYRIDAMAL 100
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PYRIDAMAL 100 (PYRIDAMAL 100).
Dipyridamole inhibits platelet phosphodiesterase, reducing platelet aggregation; also inhibits adenosine deaminase and increases extracellular adenosine, leading to vasodilation.
| Metabolism | Hepatic glucuronidation; minor CYP metabolism |
| Excretion | Renal: 50-70% unchanged; biliary/fecal: 20-30% as metabolites; total renal elimination ~85% |
| Half-life | Terminal half-life 10-12 hours; clinical context: steady state achieved in 3-5 days; renal impairment prolongs half-life |
| Protein binding | 95-98% bound to albumin and alpha-1-acid glycoprotein |
| Volume of Distribution | Vd 0.5-0.8 L/kg; clinical meaning: moderate distribution, mainly in extracellular fluid |
| Bioavailability | Oral: 85-95%; no significant first-pass effect |
| Onset of Action | Oral: 1-2 hours; IV: 15-30 minutes; IM: 5-10 minutes |
| Duration of Action | Oral: 8-12 hours; IV: 6-8 hours; clinical notes: sustained antiplatelet effect persists for 24-48 hours |
100 mg orally three times daily.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 100 mg twice daily; CrCl 10-29 mL/min: 100 mg once daily; CrCl <10 mL/min: 100 mg every 48 hours. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated. |
| Pediatric use | 1-2 mg/kg/day orally divided every 8-12 hours; maximum 300 mg/day. |
| Geriatric use | Start at 50 mg twice daily; titrate based on renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PYRIDAMAL 100 (PYRIDAMAL 100).
| Breastfeeding | Pyrilamine: Excretion into breast milk likely; M/P ratio not reported. Due to potential for irritability and drowsiness in the infant, caution is advised. Pyridoxine: Excreted into breast milk; essential nutrient, but excessive doses may inhibit lactation. The combination PYRIDAMAL 100 should be used during breastfeeding only if the benefit outweighs risk. |
| Teratogenic Risk | Pyrilamine: FDA Pregnancy Category B. Animal studies have not demonstrated teratogenic effects, but no adequate controlled studies in pregnant women. Risk cannot be ruled out. First trimester: Generally avoided unless benefit outweighs risk, as with all antihistamines due to theoretical concerns. Second/Third trimester: No specific increase in congenital anomalies documented, but drug should be used only if clearly needed. Pyridoxine (vitamin B6): No teratogenic effects in human studies; considered safe at recommended doses. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to dipyridamole","Patients with acute myocardial infarction with hemodynamic instability"]
| Precautions | ["Hypotension risk due to vasodilation","Hepatic impairment may alter drug levels","May aggravate angina in patients with coronary artery disease","Use caution in patients with hypotension, severe coronary artery disease (e.g., unstable angina, recent MI)"] |
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| Fetal Monitoring | No specific monitoring required beyond routine pregnancy care. If used near term, monitor neonatal heart rate, respiration, and alertness due to potential anticholinergic effects of pyrilamine. |
| Fertility Effects | No evidence of adverse effects on fertility or reproduction from pyrilamine or pyridoxine at therapeutic doses. |