What is the bioavailability of the drug?

The bioavailability of a drug is determined by the nature of the dosage form, which depends in part on its dosage form and formulation. Differences in bioavailability between formulations of drugs are of great clinical significance.

In Pharmacology, bioavailability has English name as bioavailability, abbreviated as BA. Bioavailability is a measure of the rate and extent of absorption of a drug substance from a preparation into the general circulation intact and bringing them to the site of action for further metabolism in the body and elimination. outside.
From the definition, drugs given intravenously have a bioavailability of 100%. However, when the drug is used in different ways (such as oral, injection, infusion...) the bioavailability of the drug is often reduced or changed depending on the patient's condition.
Bioavailability is considered an essential tool in biopharmaceuticals, an important measure to help determine and calculate drug dosage for non-intravenous dosage forms.
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Has absolute bioavailability and relative bioavailability. In which:
Absolute bioavailability: It is understood as the ratio of the AUC value obtained when the drug is administered from outside the intravenous route to the AUC value through the intravenous route of a certain drug.
F % absolute = oral AUC/ AUC(IV)* D (IV)/ D( oral) In which:
D is the dose of each drug taken into the body.
If the drug is indicated for intravenous administration, then F = l. In case the drug is given intravenously, there will always be a certain amount of loss unless it moves from the site of absorption into the bloodstream or becomes inactive when it passes through the liver, so F will always be < l. For drugs that cannot be administered intravenously, patients can use a dilute form of medicine (oral suspension, solution) for comparison. >>> Things to know about the drug Albumin
If the absolute bioavailability of the oral drug is > 50%, it is acceptable.
When bioavailability is > 80%/, the penetration of the drug into the blood will approximate that of intravenous administration.
If bioavailability is < 50%, oral form is often ineffective in severe disease. In order to be effective, the oral dose must be much larger than the injection dose.
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Relative bioavailability: It is the ratio of comparison between 2 bioavailability values ​​of an active ingredient, a route of drug delivery, and a dose but 2 different dosage forms or from 2 different drug manufacturers.
Relative F = F(A)/ F(B) Currently, relative bioavailability is used for the purpose of comparing two drugs from two different manufacturers (usually oral or tablet form with liquid).
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Meaning of relative bioavailability:
Drugs with relative bioavailability > 50% are considered good if taken orally. Drugs with relative bioavailability >80% were assessed as having an oral absorption comparable to that of parenteral administration. In this case, injections will be given to the patient in case the drug is not self-administered. If the relative bioavailability is 80-120%, then the two medicinal products can be considered equivalent and can be substituted in the treatment of certain diseases.