SUSTOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SUSTOL (SUSTOL).
Serotonin 5-HT3 receptor antagonist; blocks serotonin binding at 5-HT3 receptors in the chemoreceptor trigger zone and gastrointestinal tract, preventing nausea and vomiting.
| Metabolism | Primarily metabolized by CYP2D6 and CYP3A4; minor contribution from CYP1A2, CYP2C9, CYP2C19, and CYP2E1. |
| Excretion | Renal: approximately 22% (unchanged drug); fecal: approximately 47% (as metabolites); biliary: contributes to fecal elimination; total clearance 0.6–1.0 L/min. |
| Half-life | Terminal half-life: approximately 40 hours (range 30–50 h) in patients with normal hepatic function; prolonged in hepatic impairment (up to 2-fold). |
| Protein binding | Approximately 95% bound to plasma proteins (mainly alpha-1-acid glycoprotein). |
| Volume of Distribution | Volume of distribution: 11–13 L/kg (extensive extravascular distribution). |
| Bioavailability | Subcutaneous: absolute bioavailability is 100% (compared to IV). |
| Onset of Action | Subcutaneous: antiemetic effect begins within 30 minutes to 2 hours. |
| Duration of Action | Subcutaneous: antiemetic effect lasts up to 24 hours (single dose); supports once-daily dosing for chemotherapy-induced nausea and vomiting. |
Adults: 0.3 mg/kg (maximum 30 mg) subcutaneously once weekly.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for any degree of renal impairment. |
| Liver impairment | No dose adjustment required for Child-Pugh Class A or B. Not studied in Child-Pugh Class C. |
| Pediatric use | Safety and efficacy not established in pediatric patients. |
| Geriatric use | No specific dose adjustment; dose selection should be cautious, reflecting greater frequency of decreased hepatic, renal, or cardiac function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SUSTOL (SUSTOL).
| Breastfeeding | Not known if excreted in human milk. M/P ratio not available. Caution advised. Consider developmental and health benefits of breastfeeding along with mother's clinical need. No adverse effects reported in nursing infants. |
| Teratogenic Risk | FDA Pregnancy Category B. Animal reproduction studies have not revealed evidence of fetal harm. No adequate and well-controlled studies in pregnant women. Risk cannot be ruled out. Use only if clearly needed. First trimester: Theoretical risk based on mechanism (5-HT3 antagonist); no human data. Second and third trimesters: No known specific risks. Postmarketing reports do not suggest increased malformations. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to granisetron or any component of the formulation","Concomitant use with apomorphine"]
| Precautions | ["Serotonin syndrome with concomitant serotonergic drugs","Hypersensitivity reactions including anaphylaxis","QT interval prolongation","Masking of progressive ileus and/or gastric distension","Hepatic impairment","Serotonin syndrome risk with MAOIs"] |
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| Fetal Monitoring | No specific monitoring required. Standard obstetric monitoring. Monitor for maternal adverse effects (e.g., QT prolongation, serotonin syndrome if used with other serotonergic drugs). Fetal heart rate monitoring not indicated. |
| Fertility Effects | No known effect on fertility. Animal studies showed no impairment of fertility at doses up to 36 mg/kg/day (approximately 6 times the maximum recommended human dose). |