ENTEREG
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ENTEREG (ENTEREG).
Selective 5-HT4 receptor agonist; enhances gastrointestinal motility by increasing peristalsis and accelerating colonic transit.
| Metabolism | Primarily metabolized by cytochrome P450 3A4 (CYP3A4); also involves CYP2D6 and CYP2C9 to a lesser extent. |
| Excretion | Primarily hepatobiliary excretion; unchanged drug and major metabolite (alvimopan) undergo extensive biliary elimination with fecal excretion accounting for >90% of total elimination. Renal excretion is minimal (<5% as unchanged drug). |
| Half-life | Terminal half-life is approximately 10–17 hours in healthy subjects. Clinically, the half-life may be prolonged in severe hepatic impairment but is not significantly altered in renal impairment. |
| Protein binding | Approximately 80–90% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is about 30 L (approximately 0.4 L/kg), indicating distribution into extracellular fluid and tissues. |
| Bioavailability | Oral bioavailability is approximately 6–10% due to extensive first-pass metabolism; the drug is administered orally for local gastrointestinal activity. |
| Onset of Action | Oral administration: onset within 15–30 minutes for acceleration of gastrointestinal recovery after bowel resection. |
| Duration of Action | Duration of effect is approximately 12–24 hours; multiple dosing is typically used for up to 7 days postoperatively to maintain effect. |
| Molecular Weight | 318.47 |
Adults: 12 mg orally twice daily for up to 15 days, initiated within 30 minutes prior to surgery and continued postoperatively.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (CrCl ≥30 mL/min). Not recommended for severe renal impairment (CrCl <30 mL/min) or dialysis. |
| Liver impairment | No dose adjustment for mild to moderate hepatic impairment (Child-Pugh A or B). Caution in severe hepatic impairment (Child-Pugh C); no specific dose recommendation. |
| Pediatric use | Not FDA-approved for pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment; use with caution due to potential increased sensitivity and renal function decline. Monitor for adverse effects. |
| 1st trimester | No adequate studies in pregnant women; use only if potential benefit justifies potential risk to fetus. |
| 2nd trimester | No adequate studies in pregnant women; use only if potential benefit justifies potential risk to fetus. |
| 3rd trimester | No adequate studies in pregnant women; use only if potential benefit justifies potential risk to fetus. |
Clinical note
Comprehensive clinical and safety monograph for ENTEREG (ENTEREG).
| Placental transfer | Not studied; molecular weight suggests possible transfer. |
| Breastfeeding | Not known if excreted in human milk; caution advised. |
| Lactation Rating |
■ FDA Black Box Warning
No FDA boxed warning.
| Serious Effects |
Hypersensitivity to the drug or any component of the formulation
| Precautions | May cause diarrhea, leading to electrolyte disturbances or hypovolemia, Use with caution in patients with severe renal impairment, Avoid use in patients with a history of mechanical gastrointestinal obstruction, perforation, or severe inflammatory bowel disease |
| Food/Dietary | No specific food interactions reported. However, as ENTEREG is administered in a hospital setting, patients should follow the prescribed diet (typically clear liquids advancing to regular diet as tolerated postoperatively). Avoid grapefruit juice as it may affect drug metabolism via CYP3A4 (though not specifically studied, caution is advised). |
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| Teratogenic Risk | No human data; animal studies at doses up to 10 mg/kg/day in rats and rabbits showed no teratogenicity at exposures lower than human dose; risk cannot be excluded due to lack of adequate human studies. |
| Fetal Monitoring | Monitor for gastrointestinal adverse effects in mother; fetal monitoring not specifically recommended; standard prenatal care. |
| Fertility Effects | No human data; in animal studies at high doses, no adverse effects on fertility observed. |
| Clinical Pearls | ENTEREG (alvimopan) is a peripherally acting mu-opioid receptor antagonist indicated to accelerate postoperative recovery of GI function after bowel resection surgery. It does not cross the blood-brain barrier, so it does not reverse opioid analgesia. Use is restricted to hospitalized patients; it should not be used for more than 7 days. Contraindicated in patients who have taken therapeutic doses of opioids for >7 consecutive days immediately prior to initiation, as it may precipitate opioid withdrawal. Monitor for GI adverse effects such as nausea, vomiting, and abdominal pain. |
| Patient Advice | Take ENTEREG exactly as prescribed; do not take more than the recommended dose. · This medication is used only in the hospital after bowel surgery to help your bowels start working again. · It does not reduce pain or interfere with your pain medication. · Report any severe abdominal pain, nausea, vomiting, or diarrhea to your healthcare provider. · Do not take this medication if you have recently taken opioid pain medications for more than 7 days in a row. |