drugs
Drug Absorption
Causes of Low Bioavailability
A number of other factors may affect the absorption and bioavailability of a drug taken by mouth. Physiologic characteristics include How long the stomach takes to empty What the acidity (pH) of the stomach is How quickly the drug is moved through the digestive tract Other factors include a person's age, sex, level of physical activity, and level of stress. Food, other drugs, and digestive disorders can affect drug absorption and bioavailability. For example, high-fiber foods and calcium supplements may bind with a drug and prevent it from being absorbed. Laxatives and diarrhea, which speed up the passage of substances through the digestive tract, may reduce drug absorption. Surgical removal of parts of the digestive tract (such as the stomach or colon) may also affect drug absorption. Where and how long a drug product is stored can affect drug bioavailability. The drug in some products deteriorates and becomes ineffective or harmful if stored improperly or kept too long. Some products must be stored in the refrigerator or in a cool, dry, or dark place. Storage directions and expiration dates should be strictly adhered to (complied with) at all times. 