ATC Group: D10A Anti-acne preparations for topical use

Adapalene is a retinoid-like compound which in, in vivo and in vitro models of inflammation, has been demonstrated to possess anti-inflammatory properties. Mechanically, adapalene binds like tretinoin to specific retinoic acid nuclear receptors but, unlike tretinoin not to cytosolic receptor binding proteins. Adapalene is used in the treatment of acne and is also used (off-label) to treat keratosis pilaris as well as other skin conditions.

Aluminium chloride hexahydrate acts locally, in the stratum comeum and in the terminal duct, to relieve hyperhidrosis. It is is acidic and is thought to act by diffusing into the sweat ducts where on neutralisation it forms gelatinous hydroxides which obstruct the flow of sweat.

Azelaic Acid is a naturally occurring dicarboxylic acid. Azelaic acid possesses antibacterial, keratolytic, comedolytic, and anti-oxidant activity. Azelaic acid is bactericidal against Proprionibacterium acnes and Staphylococcus epidermidis due to its inhibitory effect on the synthesis of microbial cellular proteins.

Benzoyl peroxide is a highly lipophilic, oxidising agent with keratolytic and bacteriocidal effects. The effectiveness of benzoyl peroxide in the treatment of acne vulgaris is primarily attributable to its antibacterial activity, especially with respect to Propionibacterium acnes. Benzoyl peroxide is also believed to be effective in the treatment of acne on account of its anti-inflammatory and mild keratolytic properties.

Chloramphenicol is a broad spectrum antibiotic which has activity against many types of Gram-positive and Gram-negative bacteria. It acts by interfering with bacterial protein synthesis. Chloramphenicol is widely distributed in body tissues and fluids and enters the cerebrospinal fluid.

Clindamycin is a lincosamide antibiotic with a primarily bacteriostatic action against Gram-positive aerobes and a wide range of anaerobic bacteria. Lincosamides such as clindamycin bind to the 50S subunit of the bacterial ribosome and inhibit the early stages of protein synthesis.

Dexamethasone is a synthetic glucocorticoid; it combines high anti-inflammatory effects with low mineralocorticoid activity. It has an approximately 7 times greater anti-inflammatory potency than prednisolone, another commonly prescribed corticosteroid. At high doses it reduces the immune response.

Erythromycin exerts its antimicrobial action by binding to the 50S ribosomal sub-unit of susceptible microorganisms and suppresses protein synthesis. Erythromycin is bacteriostatic and bactericidal depending on its concentration and the type of organism.

Fluorometholone is a synthetic corticosteroid (glucocorticoid), a derivative of desoxyprednisolone. It is a member of the group of universally known steroids used for the treatment of eye inflammation. Glucocorticosteroids bind to cytoplasmic receptors and control the synthesis of infection mediators thus damping inflammatory reactions (swelling, fibrin deposition, capillary dilatation, phagocyte migration) and also capillary proliferation, collagen deposition and scarring.

Isotretinoin is a stereoisomer of all-trans retinoic acid (tretinoin). The exact mechanism of action of isotretinoin has not yet been elucidated in detail, but it has been established that the improvement observed in the clinical picture of severe acne is associated with suppression of sebaceous gland activity and a histologically demonstrated reduction in the size of the sebaceous glands. Furthermore, a dermal anti-inflammatory effect of isotretinoin has been established.

Methylprednisolone is a synthetic glucocorticoid and a methyl derivative of prednisolone. Methylprednisolone is a potent anti-inflammatory agent with the capacity to profoundly inhibit the immune system.

Minocycline is a semi-synthetic derivative of tetracycline. Minocycline inhibits protein synthesis in susceptible bacteria. In common with other tetracyclines it is primarily bacteriostatic and has a similar spectrum of activity to other tetracyclines.

The sulfonamides are bacteriostatic agents and the spectrum of activity is similar for all. Sulfonamides inhibit bacterial synthesis of dihydrofolic acid by preventing the condensation of the pteridine with aminobenzoic acid through competitive inhibition of the enzyme dihydropteroate synthetase.

Tretinoin decreases cohesiveness of follicular epithelial cells resulting in decreased microcomedone formation. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells, causing extrusion of the comedones.

Trifarotene is an agonist of retinoic acid receptors (RAR), with particular activity at the gamma subtype of RAR. Stimulation of RAR results in modulation of target genes which are associated with various processes, including cell differentiation and mediation of inflammation. Trifarotene cream is used for the topical treatment of acne vulgaris.