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Intravascular administration does not involve absorption, and there is no loss of drug. [4] The fastest route of absorption is inhalation. [5] Absorption is a primary focus in drug development and medicinal chemistry, since a drug must be absorbed before any medicinal effects can take place. Moreover, the drug's pharmacokinetic profile can be ...
Drug administration via the nasal cavity yields rapid drug absorption and therapeutic effects. [33] This is because drug absorption through the nasal passages does not go through the gut before entering capillaries situated at tissue cells and then systemic circulation and such absorption route allows transport of drugs into the central nervous ...
Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems. More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set of metabolic pathways that modify the chemical structure of xenobiotics, which are compounds foreign to an organism's normal biochemistry, such as any drug ...
Multiphasic absorption: Drugs injected intravenously are removed from the plasma through two primary mechanisms: (1) Distribution to body tissues and (2) metabolism + excretion of the drugs. The resulting decrease of the drug's plasma concentration follows a biphasic pattern (see figure). Plasma drug concentration vs time after an IV dose
A few drugs such as alcohol are absorbed by the lining of the stomach, and therefore tend to take effect much more quickly than the vast majority of oral medications which are absorbed in the small intestine. Gastric emptying time can vary from 0 to 3 hours, [2] and therefore plays a major role in onset of action for orally administered drugs ...
Whether a drug is taken with or without food will also affect absorption, other drugs taken concurrently may alter absorption and first-pass metabolism, intestinal motility alters the dissolution of the drug and may affect the degree of chemical degradation of the drug by intestinal microflora.
Drug delivery systems have been around for many years, but there are a few recent applications of drug delivery that warrant 1. Drug delivery to the brain: Many drugs can be harmful when administered systemically; the brain is very sensitive to medications and can easily cause damage if a drug is administered directly into the bloodstream.
Furthermore, after absorption from the gastrointestinal tract, such drugs must pass to the liver, where they may be extensively altered; this is known as the first pass effect of drug metabolism. Due to the digestive activity of the stomach and intestines, the oral route is unsuitable for certain substances, such as salvinorin A