Factors Influencing Drug Absorption: Disease States and Pharmacology

Various disease conditions can influence the body's blood flow and the functioning of the gastrointestinal system, influencing the drug absorption process.

Gastrointestinal diseases altering GI motility, such as diarrhea, decreasing acid secretions or achlorhydria, and infections reduce drug absorption.

Alcohol consumption and certain drugs, like antineoplastics, impair drug absorption.

Celiac disease involves damage to the small intestine's villi. It leads to decreased absorptive surface area, alters gastric emptying and intestinal activity, and impairs drug absorption for drugs, such as antibiotics, acetaminophen, and practolol.

Crohn's disease, characterized by transmural inflammation, damages intestinal integrity, resulting in an altered drug absorption process.

Congestive heart failure reduces the heart's pumping efficiency, which lowers blood flow to the GI tract and causes intestinal edema. As a result, the absorption of oral drugs such as loop diuretics is decreased.

Hepatic disorders, such as cirrhosis, decrease portal blood flow and first-pass metabolism of drugs, especially with a narrow therapeutic window, resulting in toxicity.