The study was prematurely terminated because of unavailibility of Methylnaltrexone in the region

42 patients admitted in ICU with intolerance to enteral feeding (GRV more than 250 ml) are recruited. All patients enter a primary acetaminophen absorption test study as baseline. Serum levels of acetaminophen will be measured by florescence polarization method at 15,30,45,60,90,120,180,240,480 minutes after enteral administration of 975 mg acetaminophen. Then the patients will be randomized to methylnaltrexone or erythromycin group.Another acetaminophen absorption test with the same schedule will be done after the last dose of each drug.The area under the curve for acetaminophen blood level will be used to compare the effect of two studied drugs on gastric emptying time.

Inclusion Criteria:

• Patients admitted in intensive care unit in a university affiliated hospital
• Receiving continuous enteral feeding through a nasogastric tube
• Gastric residual volume more than 250 ml checked by aspiration technique

Exclusion Criteria:

• Receiving the study drugs or metoclopramide within 24 hours of inclusion

• Known allergy to interventional drugs or acetaminophen

• Gastrointestinal bleeding or surgery on GI system within 24 hours of inclusion

• Crohn's disease

• GI perforation or obstruction

• Short bowel syndrome

• Liver failure or 2 of the followings:

  • Transaminase enzymes more than 3 times normal
  • Prothrombin time more than 2 times normal
  • Total bilirubin more than 3 times normal

• Patients on hemodialysis or CRRT

• Hemodynamically unstable patients including:

  • Mean arterial pressure less than 65 mmHg
  • Infusion of inotropes and vasopressors
  • Uncorrected acute blood loss; hemoglobin concentration less than 6.5 mg%.

• Documented or suspected pregnancy

• Obesity; actual body weight more than 1.5 times ideal body weight

• Myasthenia Gravis.

• Opioid drug abuse