Therefore, dermatologists prefer antibiotics as part of combination therapy and not for use alone.Commonly used antibiotics, either applied to the skin or taken orally, include clindamycin, erythromycin, metronidazole, sulfacetamide, and tetracyclines (e.g., doxycycline or minocycline). Doxycycline 40 milligrams daily (low-dose) appears to have similar efficacy to 100 milligrams daily and has fewer gastrointestinal side effects. However, low-dose doxycycline is not FDA-approved for the treatment of acne. Antibiotics applied to the skin are typically used for mild to moderately severe acne. Oral antibiotics are generally more effective than topical antibiotics and produce faster resolution of inflammatory acne lesions than topical applications. Topical and oral antibiotics are not recommended for use together.Oral antibiotics are recommended for no longer than three months as antibiotic courses exceeding this duration are associated with the development of antibiotic resistance and show no clear benefit over shorter durations. If long-term oral antibiotics beyond three months are used, then it is recommended that benzoyl peroxide or a retinoid be used at the same time to limit the risk of C. acnes developing antibiotic resistance.The antibiotic dapsone is effective against inflammatory acne when applied to the skin. It is generally not a first-line choice due to its higher cost and a lack of clear superiority over other antibiotics. Topical dapsone is sometimes a preferred therapy in women or for people with sensitive or darker-toned skin. It is not recommended for use with benzoyl peroxide due to the risk of causing yellow-orange skin discoloration with this combination.
7α-TMS may also be hydroxylated at the C3α and C3β positions. Spironolactone is dethioacetylated into canrenone. Finally, the C17 γ-lactone ring of spironolactone is hydrolyzed by the paraoxonase PON3. It was originally thought to be hydrolyzed by PON1, but this was due to contamination with PON3. Elimination
The majority of spironolactone is eliminated by the kidneys, while minimal amounts are handled by biliary excretion. Chemistry
Spironolactone, also known as 7α-acetylthiospirolactone, is a steroidal 17α-spirolactone, or more simply a spirolactone. It can most appropriately be conceptualized as a derivative of progesterone, itself also a potent antimineralocorticoid, in which a hydroxyl group has been substituted at the C17α position (as in 17α-hydroxyprogesterone), the acetyl group at the C17β position has been cyclized with the C17α hydroxyl group to form a spiro 21-carboxylic acid γ-lactone ring, and an acetylthio group has been substituted in at the C7α position. These structural modifications of progesterone confer increased oral bioavailability and potency, potent antiandrogenic activity, and strongly reduced progestogenic activity. The C7α substitution is likely responsible for or involved in the antiandrogenic activity of spironolactone, as 7α-thioprogesterone (SC-8365), unlike progesterone, is an antiandrogen with similar affinity to the AR as that of spironolactone. In addition, the C7α substitution appears to be responsible for the loss of progestogenic activity and good oral bioavailability of spironolactone, as SC-5233, the analogue of spironolactone without a C7α substitution, has potent progestogenic activity but very poor oral bioavailability similarly to progesterone.