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There is no regulatory requirement to define the intravenous pharmacokinetics or absolute bioavailability however regulatory authorities do sometimes ask for absolute bioavailability information of the extravascular route in cases in which the bioavailability is apparently low or variable and there is a proven relationship between the ...
As the contact time between the contaminant and soil increases, a decrease in bioavailability is observed, termed “ageing”, due to diffusion and sorption processes with mineral and organic fractions of soil. [5] Environmental conditions influence bioavailability. Drought conditions result in lower soil water content. This can reduce the ...
First-pass metabolism may occur in the liver (for propranolol, lidocaine, clomethiazole, and nitroglycerin) or in the gut (for benzylpenicillin and insulin). [4] The four primary systems that affect the first pass effect of a drug are the enzymes of the gastrointestinal lumen, [5] gastrointestinal wall enzymes, [6] [7] [8] bacterial enzymes [5] and hepatic enzymes.
Factors such as poor compound solubility, gastric emptying time, intestinal transit time, chemical instability in the stomach, and inability to permeate the intestinal wall can all reduce the extent to which a drug is absorbed after oral administration. Absorption critically determines the compound's bioavailability.
Formulation studies then consider such factors as particle size, polymorphism, pH, and solubility, as all of these can influence bioavailability and hence the activity of a drug. The drug must be combined with inactive ingredients by a method that ensures that the quantity of drug present is consistent in each dosage unit e.g. each tablet.
Grapefruit juice increases the bioavailability of sildenafil, the active ingredient in Viagra. It also delays your body’s processing of sildenafil. It also delays your body’s processing of ...
Druglikeness is a qualitative concept used in drug design for how "druglike" a substance is with respect to factors like bioavailability. It is estimated from the molecular structure before the substance is even synthesized and tested. A druglike molecule has properties such as:
Studies have shown that low levels of biotin lead to hair loss, which is why most beauty supplements contain this vitamin. One such study revealed 38% of women suffering from hair loss had a ...