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Therefore, a drug given by the intravenous route will have an absolute bioavailability of 100% (f = 1), whereas drugs given by other routes usually have an absolute bioavailability of less than one. If we compare the two different dosage forms having same active ingredients and compare the two drug bioavailability is called comparative ...
The oral route is limited to formulations containing small molecules only while biopharmaceuticals (usually proteins) would be digested in the stomach and thereby become ineffective. Biopharmaceuticals have to be given by injection or infusion. However, recent research found various ways to improve oral bioavailability of these drugs.
The bioavailability of ergotamine is around 2% orally, 6% rectally, and 100% by intramuscular or intravenous injection. [17] The low oral and rectal bioavailability is due to low gastrointestinal absorption and high first-pass metabolism. [17] Ergotamine may not readily cross the blood–brain barrier. [22] [23]
A BV of 100% indicates complete utilization of a dietary protein, i.e. 100% of the protein ingested and absorbed is incorporated into proteins into the body. The value of 100% is an absolute maximum, no more than 100% of the protein ingested can be utilized (in the equation above N e(u) and N e(f) cannot go negative, setting 100% as the maximum ...
Estimates of bioavailability can also be obtained from chemical solid-phase soil extractions. [7] Fugacity modelling of bioavailability is based on the solubility and partitioning of compounds into aqueous and non-aqueous phases. [8] This model describes the tendency for contaminants to be dissolved in the soil solution.
The drug travels by some route of administration (oral, topical-dermal, etc.) in a chosen dosage form (e.g., tablets, capsules, or in solution). [3] Absorption by some other routes, such as intravenous therapy , intramuscular injection , enteral nutrition , is even more straightforward and there is less variability in absorption and ...
Theophylline is naturally found in cocoa beans. Amounts as high as 3.7 mg/g have been reported in Criollo cocoa beans. [20] Trace amounts of theophylline are also found in brewed tea, although brewed tea provides only about 1 mg/L, [21] which is significantly less than a therapeutic dose.
Steady state plasma concentrations are achieved within one to three days. Exposure increases in a dose-related manner and following three days of intramuscular dosing, little accumulation is observed. The bioavailability of the drug is reduced by approximately 50% if a meal is not eaten before Ziprasidone ingestion. [14] [49]