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In contrast to peripheral administration, when administered intranasally via a nasal spray, oxytocin reliably crosses the blood–brain barrier and exhibits psychoactive effects in humans. [ 32 ] [ 33 ] In addition, unlike the case of peripheral administration, intranasal oxytocin has a central duration of at least 2.25 hours and as long as 4 ...
The absorption rate constant K a is a value used in pharmacokinetics to describe the rate at which a drug enters into the system. It is expressed in units of time −1. [1] The K a is related to the absorption half-life (t 1/2a) per the following equation: K a = ln(2) / t 1/2a. [1] K a values can typically only be found in research articles. [2]
The rate constant kel represents clearance by the kidneys, MPS, and any other non-tumor elimination processes, such that when kb = 0, k10 = kepr + kel where kel is the elimination rate constant. (C) Standard two compartment model with central and peripheral compartments. c1 and c2 represent the drug concentration in blood (central compartment ...
C 0 is the initial concentration (t = 0) k e is the elimination rate constant; The relationship between the elimination rate constant and half-life is given by the following equation: = / Because ln 2 equals 0.693, the half-life is readily calculated from the elimination rate constant.
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 pharmacokinetics of dienogest are linear; single oral doses of dienogest were found to result in maximal levels of 28 ng/mL with 1 mg, 54 ng/mL with 2 mg, 101 ng/mL with 4 mg, and 212 ng/mL with 8 mg. [7] The corresponding area-under-the-curve levels were 306, 577, 1153, and 2293 ng/mL, respectively. [7]
[199] [200] In a study of topical application of hydrocortisone solution in men, skin permeability (defined as total radiolabeled urinary excretion) relative to the forearm (1.0) was 42.0 for the scrotum, 13.0 for the jaw angle, 6.0 for the forehead, 3.6 for the underarm, 3.5 for the scalp, 1.7 for the back, 0.8 for the palm of the hand, 0.4 ...
The Oxford University chemical safety data documents an LD50 toxicology test on rats, both male and female, where doses are recorded as 1680 mg and 1575 mg per kg body weight respectively. [3] As such, the overdose limits for humans and animals are quite high, reaching into grams, and the compound is seen as safe for daily use for animals.