<unk> adiol valerate, an<unk>  of<unk> adiol and one of the most widely used<unk> ogen<unk> s. It has increased oral bioavailability and a longer duration with intramuscular injection relative to<unk> adiol. A<unk>  is an<unk>  of a<unk> . They include androgen<unk> s,<unk> ogen<unk> s, progestogen<unk> s, and corticosteroid<unk> s.<unk> s may be naturally occurring/endogenous like DHEA sulfate or synthetic like<unk> adiol valerate.<unk> ification is useful because it is often able to render the parent<unk>  into a prodrug of itself with altered chemical properties such as improved metabolic stability, water solubility, and/or lipophilicity. This, in turn, can enhance pharmacokinetics, for instance by improving the<unk> 's bioavailability and/or conferring depot activity and hence an extended duration with intramuscular or subcutaneous injection.<unk> ification of<unk> s with fatty acids was developed to prolong the duration of effect of<unk>  hormones. By 1957, more than 500<unk> s had been synthesized, most frequently of androgens. The longer the fatty acid chain, up to a certain optimal length, the longer the duration when prepared as an oil solution and injected. Across a chain length range of 6 to 12 carbon atoms, a length of 9 or 10 carbon atoms (nonanoate or decanoate<unk>  was found to be optimal in rodents in the case of testosterone<unk> s. Fatty acid<unk> s increase the lipophilicity of<unk> s, with longer fatty acids resulting in greater lipophilicity. The greater solubility in oil allows the<unk> s to be dissolved in a smaller oil volume, thereby allowing for larger doses with intramuscular injection. In addition, the greater the lipophilicity of the<unk> , as measured by the octanol/water partition coefficient (logP), the slower its release from the oily depot at the injection site and the longer its duration.<unk> s can also be prepared as crystalline aqueous suspensions. Aqueous suspensions of<unk>  crystals result in prolongation of duration with intramuscular injection similarly to oil solutions. The duration is longer than that of oil solutions, intermediate between oil solutions and subcutaneous pellet implants. The sizes of crystals in suspensions varies and can range from 0.1 μm to some hundreds of μm. The duration of crystalline<unk>  suspensions increases directly with the size of the crystals. However, crystalline suspensions have an irritating effect in the body, and intramuscular injections of crystalline<unk>  suspensions result in painful local reactions. These reactions worsen with larger crystals, and for this reason, crystal sizes must be limited to minimize local reactions. Particle sizes of more than 300 μg in the case of<unk> adiol benzoate by intramuscular injection have been found to be too painful for use. In some cases, crystalline<unk>  suspensions are used not for prolongation of effect, but because the solubility of the<unk>  result in this preparation being the only practical way to deliver the<unk>  in a reasonable injection volume. Examples include cortisone acetate and hydrocortisone and its<unk> s. A requirement of long-lasting crystalline<unk>  administration is that the<unk>  be sufficiently water-insoluble, so that it dissolves slowly and thereby attains a prolonged therapeutic effect. The crystals in suspensions can sometimes clump together or aggregate and grow in size. This can be avoided by careful formulation. Crystalline suspensions of<unk> s are prepared either by precipitation or by dispersing finely divided material in an aqueous suspension medium. Desired particle size can be achieved by grinding, for instance through the use of an atomizer. Adolf Butenandt reported in 1932 that<unk> one benzoate in oil solution had a prolonged duration with injection in animals. No such prolongation of action occurred if it was given by intravenous injection.<unk> adiol benzoate was synthesized in 1933 and was marketed for use the same year.
Steroid ester
Antimetabolite
Lipase inhibitors
Perfluorinated compound
Lipid emulsion
Sugar substitute
Immunoconjugate
Polypeptide antibiotic