Methylnaltrexone
Methylnaltrexone Uses, Dosage, Side Effects, Food Interaction and all others data.
Methylnaltrexone is a pheriphally-acting μ-opioid antagonist that acts on the gastrointestinal tract to decrease opioid-induced constipation without producing analgesic effects or withdrawal symptoms. It is also a weak CYP2D6 inhibitor. FDA approved in 2008.
Use of opioids induces slowing of gastrointestinal motility and transit. Following remifentanil administration, the methylnaltrexone and placebo groups showed no change in pupiliary constriction while the naloxone group showed a marked change over the time interval tested.
| Trade Name | Methylnaltrexone |
| Availability | Prescription only |
| Generic | Methylnaltrexone |
| Methylnaltrexone Other Names | MNTX |
| Related Drugs | lactulose, Linzess, Amitiza, Movantik, linaclotide, lubiprostone, Relistor, naloxegol, Symproic |
| Weight | 150mg, 12mg/0.6ml, 8mg/0.4ml |
| Type | Subcutaneous, Oral Tablet, Subcutaneous Solution, Oral/injection |
| Formula | C21H26NO4 |
| Weight | Average: 356.441 Monoisotopic: 356.185634741 |
| Protein binding | 11% to 15% bound to human plasma proteins. |
| Groups | Approved |
| Therapeutic Class | |
| Manufacturer | |
| Available Country | United States |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
Methylnaltrexone is a μ-opioid antagonist used for the treatment of opioid-induced constipation in palliative patients that are inadequately responding to laxative therapy.
Treatment of opioids induced constipation in palliative patients that are inadequately responding to laxative therapy.
Methylnaltrexone is also used to associated treatment for these conditions: Opioid Induced Constipation (OIC)
How Methylnaltrexone works
Methylnaltrexone is a pheriphally-acting μ-opioid antagonists that acts on the gastrointestinal tract inhibit opioid-induced decrease in gastric motility and transit time. Because methylnaltrexone is a quaternary derivative of naltrexone, it produces its gastrointestinal effects without producing analgesic effects or withdrawal symptoms as it does not cross the blood-brain-barrier.
Toxicity
LD50: 50 mg/kg (primates); Orthostatic hypotension at plasma levels in excess of 1.400 ng/mL. The most common (>5%) adverse reactions reported with methylnaltrexone bromide are abdominal pain, flatulence, nausea, dizziness, diarrhea and hyperhidrosis.
Food Interaction
- Take on an empty stomach. Take methylnaltrexone at least 30 minutes before breakfast.
[Moderate] ADJUST DOSING INTERVAL: Food may reduce the rate and extent of absorption of methylnaltrexone following oral administration.
When a single 450 mg oral dose of methylnaltrexone was administered with a high-fat breakfast (approximately 800 to 1000 calories; 60% from fat, 25% from carbohydrate, and 15% from protein) in healthy study subjects, methylnaltrexone peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 60% and 43%, respectively, while time to reach Cmax delayed by 2 hours.
MANAGEMENT: Oral methylnaltrexone should be taken with water on an empty stomach at least 30 minutes before the first meal of the day.
Methylnaltrexone Disease Interaction
Major: intestinal obstructionModerate: hepatic impairment, renal impairment
Volume of Distribution
Volume of distribution, steady state = 1.1 L/kg
Elimination Route
Methylnaltrexone is rapidly absorbed. Tmax (SubQ): 30 minutes (regardless of dose); Cmax, 0.15 mg/kg SubQ dose = 117 ng/mL; AUC24, 0.15 mg/kg SubQ dose = 175 ng·hr/mL;
Half Life
terminal: 8.89 ± 2.59 h (intravenous) terminal: 6.14- 8.83 h (subcutaneous)
Clearance
10.5 ± 1.5 ml/min/kg (IV)
Elimination Route
Most of the drug is eliminated as unchanged drug (85% of administered radioactivity). Approximately half of the dose is excreted in the urine and somewhat less in feces.
Innovators Monograph
You find simplified version here Methylnaltrexone
