Gastric emptying process

The process of gastric emptying is extremely complex and is influenced by many factors such as presence of food, food content, pH, and posture. Most drugs are not absorbed from the stomach and are therefore dependent on the gastric emptying process to deliver them to their site of absorption. Consequently, the process and factors that affect it have been extensively studied with many conflicting views reported. 

Some HGL inactivation was observed in the control experiments (29.4% with the liquid meal 12.3% with the solid meal Tab. 10.4). Partial inactivation of HGL was found to occur mostly in the samples with the lowest pH values (1-2), which were collected at the end of the meal gastric emptying process. 

Dicyclomine hydrochloride behaves both as an antimuscarinic and a nonspecific antispasmodic agent. It is frequently employed in the treatment of irritable colon, spastic colitis, mucous colitis, spastic constipation and biliary dyskinesia. It also finds its use in the diagnosis of peptic ulcer by delaying gastric emptying process. 

Older individuals have decreased host defense mechanisms such as slowed gastric emptying and decreased saliva production. They may present with atypical symptoms such as chest pain, asthma, hoarseness, coughing, wheezing, or poor dentition. These patients often do not seek medical attention because they believe their symptoms are part of the normal aging process. 

It may take many hours for the contents of the stomach to be processed and moved into the small intestine. Several factors influence gastric motility and therefore the rate of gastric emptying. These include ... 

The absorption of class III drugs is limited by their permeability over the intestinal wall. Thus, as this process is not at all modeled by the classical in vitro dissolution test, no IVIVC should be expected. When drug dissolution becomes slower than gastric emptying, a reduction in the extent of bioavailability will be found in slower dissolution rates as the time when the drug is available for permeation over the gut wall in the small intestine will then be reduced. Thus, the same type of relationship can be expected between bioavailability and in vitro dissolution, as shown in Fig. 21.12 for a class I drug. 

In addition to these receptors, enkephalins may be involved in some parts of this process, while agents which act on gastric serotonin (5-HT4), dopamine, and motilin receptors accelerate gastric emptying and relieve symptoms in gastroparesis. 

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