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Most drugs are weak organic acids or bases, existing in un-ionized and ionized forms in an aqueous environment. The un-ionized form is usually lipid soluble (lipophilic) and diffuses readily across cell membranes.
- Drug Excretion
Un-ionized forms of drugs and their metabolites tend to be...
- Overview of Pharmacokinetics
Pharmacokinetics, sometimes described as what the body does...
- Drug Bioavailability
Low bioavailability is most common with oral dosage forms of...
- Drug Excretion
Practically speaking, this means that if taken orally, a drug that is a weak acid will be absorbed primarily in the acidic environment; whereas, a drug that is a weak base will be absorbed in the alkaline environment small intestines.
27 Φεβ 2024 · Weakly acidic drugs are easily absorbed in an acidic environment such as the stomach. Meanwhile, weakly basic drugs are not absorbed until they reach the higher pH medium in the small intestine. [7] [8]
In the stomach, drugs that are weak acids (such as aspirin) will be present mainly in their non-ionic form, and weak bases will be in their ionic form. Since non-ionic species diffuse more readily through cell membranes, weak acids will have a higher absorption in the highly acidic stomach.
28 Μαρ 2024 · Since most drugs are either weak acids or weak bases, their solubility and permeability are highly dependent on the pH of the absorption site. Moreover, the electrochemical gradient should be considered to study the absorption of charged species rigourously.
1 Δεκ 2018 · To diffuse, drugs should be sufficiently hydrophobic to partition into the lipid bilayer of the plasma membrane. Since most drugs are either weak acids or bases, the ability of a given drug to partition into the membrane will be highly modified by the pH conditions.
4 Νοε 2013 · Humans. Hydrogen-Ion Concentration. Substances. Famotidine. Published reports have clearly shown that weakly basic drugs which have low solubility at high pH could have impaired absorption in patients with high gastric pH thus leading to reduced and variable bioavailability.
