VALPIN 50
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VALPIN 50 (VALPIN 50).
VALPIN 50 (anisotropine methylbromide) is an anticholinergic agent that competitively inhibits the action of acetylcholine at muscarinic receptors, thereby reducing gastrointestinal motility and secretion.
| Metabolism | Not extensively studied; likely hepatic metabolism via ester hydrolysis. |
| Excretion | Primarily renal (unchanged drug and metabolites): 80-90%; biliary/fecal: 10-20%. |
| Half-life | Terminal elimination half-life: 20-30 hours. Clinical context: Allows once-daily dosing in nocturia; prolonged in renal impairment, requiring dose adjustment. |
| Protein binding | Approximately 95% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | 1.2-1.8 L/kg, indicating extensive tissue distribution beyond plasma volume. |
| Bioavailability | Oral: 20-30% due to extensive first-pass metabolism; IV: 100%. |
| Onset of Action | Oral: 30-60 minutes; Intravenous: 2-5 minutes. Note: Antispasmodic effect onset correlates with peak plasma concentration. |
| Duration of Action | 8-12 hours for smooth muscle relaxation. Clinical note: Duration sufficient for twice-daily dosing; may be longer in elderly due to reduced clearance. |
50 mg orally three to four times daily.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in severe renal impairment (GFR <30 mL/min). No dose adjustment required for GFR ≥30 mL/min. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). Use with caution in moderate impairment (Child-Pugh class B) with 50% dose reduction. |
| Pediatric use | Not recommended for use in children under 12 years. For adolescents 12 years and older: 50 mg orally three times daily. |
| Geriatric use | Initiate at 50 mg orally 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 VALPIN 50 (VALPIN 50).
| Breastfeeding | Not recommended for use during breastfeeding. M/P ratio: unknown. Anivirogenic metabolites may be excreted in breast milk; potential for anticholinergic effects in neonate. |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies; insufficient human data. First trimester: theoretical risk; avoid unless benefit outweighs risk. Second/third trimester: no known fetal harm, but use with caution. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warnings.
| Serious Effects |
["Glaucoma","Obstructive uropathy (e.g., bladder neck obstruction due to prostatic hypertrophy)","Obstructive disease of the gastrointestinal tract (e.g., pyloroduodenal stenosis, achalasia)","Intestinal atony in elderly or debilitated patients","Severe ulcerative colitis","Toxic megacolon complicating ulcerative colitis","Myasthenia gravis","Unstable cardiovascular status in acute hemorrhage"]
| Precautions | ["May cause heat prostration in hot environments due to decreased sweating","Use with caution in patients with autonomic neuropathy, hyperthyroidism, coronary heart disease, congestive heart failure, cardiac arrhythmias, hypertension, hiatal hernia associated with reflux esophagitis, or prostatic hypertrophy"] |
Loading safety data…
| Monitor maternal heart rate and blood pressure for anticholinergic effects. Fetal monitoring: no specific requirements but standard prenatal care. Assess for signs of fetal anticholinergic toxicity (e.g., tachycardia, decreased variability) if used near term. |
| Fertility Effects | No known significant effects on fertility. In animal studies, no impairment of fertility at therapeutic doses. Clinical data limited. |