Pharmacology-4 PHL 425 Seventh Lecture By Abdelkader Ashour, Ph.D. Phone:

Anti-Acne Vulgaris Drugs

Acne Vulgaris (Acne), Overview & Pathogenesis  Acne is derived from the Greek word “Akme” which means the highest point  Acne is the formation of comedones, papules, pustules, nodules, and/or cysts as a result of obstruction and inflammation of pilosebaceous units (hair follicles and their accompanying sebaceous gland)

Acne Vulgaris (Acne), Overview & Pathogenesis  Acne is derived from the Greek word “Akme” which means the highest point  Acne is the formation of comedones, papules, pustules, nodules, and/or cysts as a result of obstruction and inflammation of pilosebaceous units (hair follicles and their accompanying sebaceous gland)

closed comedo open comedo sebaceous follicle Micro comedo Acne, Pathogenesis  Manifestations differ depending on whether P. acnes stimulates inflammation in the follicle  Comedones are termed closed (whiteheads) or open (blackheads) depending on whether the follicle is closed or dilated at the skin surface  Noninflammatory acne is characterized by comedones; uninfected sebaceous plugs “a plug of keratin and sebum” impacted within follicles  Thus, acne can be inflammatory or noninflammatory, depending on whether P. acnes stimulates inflammation in the follicle or not  Acne occurs when pilosebaceous units become obstructed with plugs of sebum and desquamated keratinocytes, then sometimes infected with the normal skin anaerobe P. acnes

Acne, Pathogenesis  Inflammatory acne comprises papules, pustules, nodules and cysts  Papules appear when lipases from P. acnes metabolize triglycerides into free fatty acids (FFA), which irritate the follicular wall

Acne, Pathogenesis  Inflammatory acne comprises papules, pustules, nodules and cysts  Pustules occur when active P. acnes infection causes inflammation within the follicle Pustule

Acne Vulgaris (Acne), Pathogenesis  Inflammatory acne comprises papules, pustules, nodules and cysts  Nodules and cysts occur when rupture of follicles due to inflammation, physical manipulation, or harsh scrubbing releases FFAs, bacteria and keratin into tissues, triggering soft-tissue inflammation

Acne, Epidemiology & Etiology  Acne vulgaris is the most common of all cutaneous disorders and occurs in more than 85% of adolescents. It is more severe in males than in females. Genetic background plays a role in the incidence of this disorder  Commonly involved areas are those with the highest concentration of sebaceous glands, that is the face, neck, chest, shoulders, and upper back.  The most common trigger is puberty, when surges in androgen stimulate sebum production and hyperproliferation of keratinocytes  Other triggers include hormonal changes that occur with pregnancy or throughout the menstrual cycle; occlusive cosmetics, cleansing agents, and clothing; and humidity and sweating  Acne may improve in summer months because of sunlight's anti-inflammatory effects  Drugs such as lithium, hydantoin, isoniazid, glucocorticoids, oral contraceptives, androgens (e.g., testosterone), iodides, bromides and danazol are contributory factors  Others: Emotional stress can definitely cause exacerbations  Occlusion and pressure on the skin, such as by leaning face on hands, very important and often unrecognized exacerbating factor (acne mechanica)  Acne is not caused by chocolate or fatty foods or, in fact, by any kind of food

Type 1: Comedones only, fewer than 10 lesions on the face, no lesions on the trunk and no scarring Type 2: Papules, 10 to 25 lesions on the face and trunk, mild scarring Type 3: Pustules, more than 25 lesions, moderate scarring Type 4: nodules or cysts, extensive scarring Severity rating for acne

Management of Acne  The withdrawal of aggravating factors such as cosmetics and drugs is paramount where they appear to be involved in the etiology of acne. Trauma, such as picking and vigorously squeezing acne lesions, can aggravate the condition  Affected areas should be cleansed daily Extra washing, use of antibacterial soaps, and scrubbing confer no added benefit Changes in diet are also unnecessary and ineffective  Treatments are directed at reducing sebum production, comedones formation, inflammation and infection  Mild and mild to moderate acne:  Single-agent therapy is generally sufficient for comedonal acne (a mainstay of treatment for comedones is daily topical tretinoin in escalating concentrations as tolerated). Azelaic acid has comedolytic and antibacterial properties and may be synergistic with retinoids  Papulopustular acne generally requires dual therapy (e.g., the combination of tretinoin with benzoyl peroxide or topical antibiotics)  Daily adapalene gel and tazarotene cream or gel are alternatives for patients who cannot tolerate topical tretinoin  Treatment should be continued for 6 wk or until lesions respond. Maintenance treatment may be necessary to maintain control  Mild inflammatory acne should be treated with topical benzoyl peroxide, topical antibiotics (e.g., erythromycin, clindamycin) and/or glycolic acid  Oral antibiotics (e.g., tetracycline, minocycline, doxycycline, erythromycin) can be used when wide distribution of lesions makes topical therapy impractical  Selection of treatment is generally based on severity

Management of Acne  Moderate acne:  Moderate acne responds best to oral systemic therapy with antibiotics. Antibiotics effective for acne include tetracycline, minocycline, doxycycline and erythromycin. Full benefit takes ≥ 12 wk  Tetracycline is usually a good first choice: 250 or 500 mg bid (between meals and at bedtime) for 4 wk or until lesions respond, after which it may be reduced to the lowest effective dose  Because relapse ordinarily follows short-term treatment, therapy must be continued for months to years, although for maintenance tetracycline 250 or 500 mg once/day is often sufficient  Minocycline 50 or 100 mg bid causes fewer GI adverse effects, is easier to take, is less likely to cause photosensitization  Erythromycin and doxycycline are considered 2nd-line agents because both can cause GI adverse effects, and doxycycline is a frequent photosensitizer  In women, prolonged antibiotic use can cause candidal vaginitis; if local and systemic therapy does not eradicate this problem, antibiotic therapy for acne must be stopped  Severe acne:  Oral Isotretinoin is nearly always effective. It is also the best treatment for patients with moderate acne in whom antibiotics are unsuccessful and for those with severe inflammatory acne  It is limited by adverse effects, including dryness of conjunctiva and genital mucosa, chapped lips, arthralgias, depression, elevated lipids and birth defects. Petrolatum usually alleviates mucosal and cutaneous dryness CBC, liver function, and fasting glucose, triglyceride, and cholesterol levels should be determined before treatment. Each should be reassessed at 4 wk and, unless abnormalities are noted, need not be repeated until the end of treatment

Inhibitors of bacterial protein synthesis, Overview  These agents are bacteriostatic, protein-synthesis inhibitors that target the ribosome  Examples: Chloramphenicol, tetracyclines, macrolides, clindamycin