ORINASE DIAGNOSTIC
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ORINASE DIAGNOSTIC (ORINASE DIAGNOSTIC).
Stimulates insulin secretion from pancreatic beta cells by binding to ATP-sensitive potassium channels, causing depolarization and calcium influx.
| Metabolism | Hepatic metabolism via CYP2C9 to inactive metabolites; renal excretion of metabolites. |
| Excretion | Renal excretion of unchanged drug and metabolites: approximately 85% renal (60% unchanged, 25% as hydroxylated metabolite), 15% biliary/fecal. |
| Half-life | Terminal elimination half-life: 4-6 hours in normal renal function; prolonged to 8-12 hours in renal impairment (creatinine clearance <50 mL/min). |
| Protein binding | 90-95% bound to serum albumin (primarily albumin). |
| Volume of Distribution | 0.1-0.2 L/kg; low Vd consistent with high protein binding and limited tissue distribution. |
| Bioavailability | Oral: approximately 85-90% (rapid and complete absorption). |
| Onset of Action | Oral: 30-60 minutes for hypoglycemic effect; intravenous (as diagnostic agent): 1-2 minutes for fall in blood glucose. |
| Duration of Action | Oral: 6-12 hours; intravenous: 1-2 hours for diagnostic glucose reduction. |
1 g intravenous bolus over 2 minutes (diagnostic test for insulinoma).
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required; contraindicated in severe renal impairment (eGFR <30 mL/min/1.73 m²) due to risk of prolonged hypoglycemia. |
| Liver impairment | Child-Pugh A/B: No adjustment needed. Child-Pugh C: Avoid use due to impaired gluconeogenesis and increased hypoglycemia risk. |
| Pediatric use | Not established; contraindicated in children due to lack of safety data. |
| Geriatric use | Use with caution; monitor blood glucose closely due to age-related decline in renal function and increased hypoglycemia susceptibility. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ORINASE DIAGNOSTIC (ORINASE DIAGNOSTIC).
| Breastfeeding | Tolbutamide is excreted into breast milk in low levels; estimated M/P ratio ~0.27. Short half-life and single diagnostic dose likely pose low risk to infant. Consider alternate diagnostic method if breast-feeding. |
| Teratogenic Risk | Tolbutamide (Orinase Diagnostic) is a sulfonylurea. First trimester: limited human data; animal studies show fetal anomalies at high doses, but risk likely low due to short diagnostic use. Second/third trimester: may cause neonatal hypoglycemia if used near term; avoid for diagnostic use in pregnancy. |
■ FDA Black Box Warning
Increased risk of cardiovascular mortality associated with oral hypoglycemic drugs; use of tolbutamide was questioned in the University Group Diabetes Program (UGDP) study.
| Serious Effects |
Type 1 diabetes mellitus, diabetic ketoacidosis, hypersensitivity to sulfonylureas or sulfonamides, severe hepatic or renal impairment.
| Precautions | Hypoglycemia, especially in elderly or debilitated patients; hepatic or renal impairment; sulfonamide allergy cross-sensitivity; disulfiram-like reaction with alcohol. |
Loading safety data…
| Fetal Monitoring |
| Monitor maternal blood glucose during test. No specific fetal monitoring required for single diagnostic dose; if used repeatedly, assess fetal growth and neonatal glucose after delivery. |
| Fertility Effects | No known significant effects on fertility in humans; animal studies show no impairment. |