Hormone replacement therapy formulations

For injectable formulations used in estrogenic hormone replacement therapy, various esters of beta-estradiol have been most widely used. 

The evidence of adverse effects emerging from randomized trials in and around 2002 has resulted in a dramatic fall in the use of hormone replacement therapy, the use of some formulations falling by two-thirds (21). Continuing debate on the benefit to harm balance of hormonal therapy at the time of the menopause or subsequently has in the recent past hardly yielded new conclusions (22). 

It is reasonable to use proprietary names when dosage, and therefore pharmaceutical bioavadability, are critical so that small variations in the amoimt of drug available for absorption can have big effects on the patient, e.g. drugs with low therapeutic ratio, digoxin, hormone replacement therapy, adrenocortical steroids (oral), antiepileptics, cardiac anti-arrhythmics, warfarin. Also, with the introduction of complex formulations, e.g. sustained-release, it is important clearly to identify these, and use of proprietary names has a role. 

Oleic acid is the common name for (Z)-9-octadece-noic acid and is a nearly colorless liquid at room temperature with a melting point of 5-7°C. Oleic acid is practically insoluble in water but has been used as a solvent for oral delivery of hydrophobic drugs in soft gelatin capsules. Oleic acid is used to solubilize ritonavir in Norvir and Kaletra soft gelatin capsules (see section Microemulsion Oral Formulations ). Testosterone undecanoate is an ester prodrug of testosterone intended for oral administration in hormone replacement therapy, and is solubilized in oleic acid in 40 mg Restandol 40 mg soft gelatin capsules. 

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