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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.
[8] [88] The bioavailability of oral testosterone undecanoate is 3 to 7%. [32] [40] Topical testosterone gels have a bioavailability of about 8 to 14% when administered to recommended skin sites including the abdomen, arms, shoulders, and thighs. [48] [49] The bioavailability of testosterone by subcutaneous implant is virtually 100%. [86]
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 bioavailability is often near 100%. Intravascular administration does not involve absorption, and there is no loss of drug. [4]
Therefore, if a drug has a bioavailability of 0.8 (or 80%) and it is administered in a dose of 100 mg, the equation will demonstrate the following: De = 0.8 × 100 mg = 80 mg. That is the 100 mg administered represents a blood plasma concentration of 80 mg that has the capacity to have a pharmaceutical effect.
[21] [36] Lacosamide is a functionalized amino acid molecule that has high solubility in water and DMSO, with a solubility of 20.1 mg/mL in phosphate-buffered saline (PBS, pH 7.5, 25 °C). [21] [37] The molecule has six rotatable bonds and one aromatic ring. Lacosamide melts at 143-144 °C and boils at 536.447 °C at a pressure of 760 mmHg.
Linezolid is an antibiotic used for the treatment of infections caused by Gram-positive bacteria that are resistant to other antibiotics. [9] [10] Linezolid is active against most Gram-positive bacteria that cause disease, including streptococci, vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA).
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]