rumours
Many people believe that taking medicine before meals means taking it on an empty stomach.
refute rumors
Taking medicine before meals is not the same as taking medicine on an empty stomach. Many people wonder, “before meals” means before eating, the stomach is empty, and “fasting” is not the same meaning? In fact, there is a difference between the two.
Taking medicines before meals means taking them about half an hour before eating. Medications that should be taken before meals include: gastrointestinal stimulants, gastric mucosal protectors, choler tablets, mucus dissolving agents. Taking medication on an empty stomach means taking it 2 to 4 hours after eating to ensure that only the medication reaches the stomach. Appropriate fasting medications are: deworming drugs, tonic herbal medicine, salt laxatives, alendronate sodium tablets.
Depending on the patient’s physiological and pathological conditions (the size of the stomach volume, the amount of gastric juice secretion, the length of gastric emptying time), the physical and chemical properties of food and drugs and other factors, fasting, before and after eating medication will produce different therapeutic effects, so the fasting medication can not simply be equated with taking medication before meals.
So, what changes in the physiological conditions of the gastrointestinal tract will affect the absorption of drugs?
Size of the stomach volume
The stomach is a hollow, sac-like organ whose main function is to temporarily store food for preliminary digestion. An adult’s stomach can usually hold 1 to 2 liters of food. After a full meal, food can slowly pass from the stomach into the small intestine.
The stimulation of food to various receptors during eating can reflexively cause the secretion of saliva, gastric juice, pancreatic juice and bile, the change of activities of stomach and gallbladder and the secretion of insulin, so as to prepare for the digestion of food.
After the food enters the stomach, it will be subjected to the mechanical action of the muscle contraction of the stomach wall and the chemical digestion of gastric juice, in which the protein is initially decomposed, and the stomach contents become porridge-like surimi, which will be discharged into the duodenum through the pylorus in small quantities.
Usually 5 minutes after the food into the stomach, the stomach can peristaltic at a frequency of 3 times per minute. Stomach peristalsis can make the drug and food fully mixed, at the same time, dispersed and stirring effect, so that the drug and gastric mucosa full contact, promote the absorption of drugs in the stomach. Each peristaltic wave can push 1~2ml of chyme drug towards the duodenum.
How much gastric juice is produced
The normal daily secretion of gastric juice is 1.5-2.5 L, and its main components are hydrochloric acid, pepsinogen, mucus, internal factors, sodium, potassium chloride. The pH of gastric juice is 0.9~1.5 when fasting, and after drinking water or eating, the pH can rise to 3.0~5.0.
As the pH of gastric juice is acidic, it is conducive to the absorption of weakly acidic drugs (less drug dissociation, high molecular type ratio, high fat solubility), which is not conducive to the absorption of weakly alkaline drugs.
In addition, the food that enters the stomach is arranged in layers according to the order of swallowing, and the food that enters the stomach first comes into contact with the stomach wall, and the food that enters the stomach after enters the center of the gastric cavity and does not come into contact with the gastric mucosa temporarily. Therefore, drugs susceptible to stomach acid should be taken before meals, and drugs that stimulate the stomach should be taken after meals.
The length of gastric emptying time
The faster the stomach empties, the shorter the time it takes for the drug to reach the small intestine, the better the absorption of the drug, and the shorter the time it takes to produce its effect.
Different foods have different emptying times, depending on the physical and chemical composition of the food. In general, dilute fluid foods empty faster than thick or solid foods, small particles empty faster than large pieces of food, isotonic fluids empty faster than non-isotonic fluids, and indigestible solid foods empty most slowly.
Among the three main nutrients, the order of emptying time from long to short is: fat>protein>sugars. After people have eaten a fatty meal, gastric movement is inhibited and gastric emptying time is prolonged. It usually takes 4~6 hours for mixed food to be completely emptied from the stomach. Temperature also has an effect on emptying, with solutions above or below body temperature emptying more slowly.
Be sure to read the drug instructions carefully before taking the drug, and take it according to the “usage” or “precautions” column of the instructions.
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