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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 ...
[2] The bioavailability of testosterone when administered as a subcutaneous pellet implant is virtually 100%. [86] Levels of testosterone vary considerably between individuals, but are fairly constant within individuals. [41] The absorption half-life of subdermal testosterone implants is 2.5 months. [8]
[190] [189] Transdermal estradiol reservoir patches have been reported to have a bioavailability of 3 to 5%. [191] Estradiol is a highly potent compound and circulates at picomolar concentrations (pg/mL), which makes it ideal for transdermal application as only small amounts of substance need to be delivered across the skin. [ 96 ]
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.
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.
At doses via the oral route with comparable systemic estrogenic potency, conjugated estrogens have about 1.3 to 4.5 times the hepatotropic potency (i.e., potency in modulating liver protein synthesis) of estradiol, ethinylestradiol has about 2.9 to 5.0 times the hepatotropic potency of estradiol, and diethylstilbestrol shows about 5.7 to 7.5 ...
The pharmacokinetics of estradiol, including its bioavailability, metabolism, biological half-life, and other parameters, differ by route of administration. [11] Likewise, the potency of estradiol, and its local effects in certain tissues , most importantly the liver , differ by route of administration as well. [ 11 ]
However, a closely related estradiol ester, estradiol decanoate (estradiol decylate), has been studied via the oral route, and has been found to possess significant oral bioavailability, to produce relatively high estradiol levels of about 100 pg/mL after a single 0.5 mg oral dose and about 100 to 150 pg/mL with continuous 0.25 mg/day oral ...