Gastric emptying delayed

Absorption. Gastrointestinal motility is decreased but there appears to be no major defect in drug absorption except that reduced gastric emptying delays the appearance in the plasma of orally administered drugs, especially during labour. Absorption from an intramuscular site is likely to be efficient because tissue perfusion is increased due to vasodilatation. 

In clinical practice, diabetes mellitus is probably the most common cause of delayed gastric emptying. Delayed emptying of both solids and liquids in this condition is attributed mainly to impaired neural... 

Most pancreatic enzyme supplements are enteric coated to release enzymes in the alkaline environment of the intestine this minimizes enzyme destruction in the stomach. Enteric-coated pancreatic enzyme supplements require fewer daily dosage units, but delivery of the drug to the site of action and effectiveness may be delayed by gastric emptying time.41... 

FIGURE 29-2. Levodopa absorption and metabolism. Levodopa is absorbed in the small intestine and is distributed into the plasma and brain compartments by an active transport mechanism. Levodopa is metabolized by dopa decarboxylase, monoamine oxidase, and catechol-O-methyltransferase. Carbidopa does not cross the blood-brain barrier. Large, neutral amino acids in food compete with levodopa for intestinal absorption (transport across gut endothelium to plasma). They also compete for transport across the brain (plasma compartment to brain compartment). Food and anticholinergics delay gastric emptying resulting in levodopa degradation in the stomach and a decreased amount of levodopa absorbed. If the interaction becomes a problem, administer levodopa 30 minutes before or 60 minutes after meals. 

Levodopa, a dopamine precursor, is the most effective agent for PD. Patients experience a 40% to 50% improvement in motor function. It is absorbed in the small intestine and peaks in the plasma in 30 to 120 minutes. A stomach with excess acid, food, or anticholinergic medications will delay gastric emptying time and decrease the amount of levodopa absorbed. Antacids decrease stomach acidity and improve levodopa absorption. Levodopa requires active transport by a large, neutral amino acid transporter protein from the small intestine into the plasma and from the plasma across the blood-brain barrier into the brain (Fig. 29-2). Levodopa competes with other amino acids, such as those contained in food, for this transport mechanism. Thus, in advanced disease, adjusting the timing of protein-rich meals in relationship to levodopa doses may be helpful. Levodopa also binds to iron supplements and administration of these should be spaced by at least 2 hours from the levodopa dose.1,8,16,25... 

Lubiprostone is a chloride channel activator that acts locally on the gut to accelerate genitourinary transit time and delay gastric emptying. It is approved for chronic idiopathic constipation in adults. The dose is 24 mg capsule twice daily with food. Lubiprostone may cause headache, diarrhea, and nausea. 

Problems with other normal mucosal defense mechanisms may also contribute to the development of GERD, including prolonged acid clearance time from the esophagus, delayed gastric emptying, and reduced mucosal resistance. 

Promotility agents may be useful as adjuncts to acid suppression therapy in patients with a known motility defect (e.g., LES incompetence, decreased esophageal clearance, delayed gastric emptying). However, these agents are generally not as effective as acid suppression therapy and have undesirable side effects. 

Gastric residual volumes Every 4-8 hours (varies) As needed when delayed gastric emptying suspected... 

Gl T Gastric pH i Gl blood flow Delayed gastric emptying Slowed intestinal transit... 

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