Pharmacology-4 PHL 425 Eighth Lecture By Abdelkader Ashour, Ph.D. Phone: 4677212 Email: aeashour@ksu.edu.sa

Anti-Acne Drugs, Examples The majority of acne patients can be treated with topical medications of three types: benzoyl peroxide products, retinoids and antibiotics. Each has distinct advantages, and concurrent use of these agents may have synergistic effects Topical benzoyl peroxide has both bactericidal and comedolytic activities This agent is particularly useful because of its bactericidal nature, and frequent use inhibits the development of bacterial resistance Irritation evidenced by erythema and scaling is the most significant side effect; skin hypopigmentation and bleaching of clothing may also occur The topical retinoids (tretinoin, adapalene, tazarotene) normalize keratinocyte differentiation, decreasing the "stickiness" of the epidermal cells lining the follicular lumen. This allows the keratin plug to be expelled, thus preventing formation of comedones All forms should be introduced gradually, to decrease the likelihood of adverse effects such as drying, irritation, or sun sensitivity. Daily therapy can usually be tolerated after several weeks; these agents are generally not used more than once a day Oral isotretinoin is the most effective drug available for the treatment of acne. It directly suppresses sebaceous gland activity leading to significant reduction in sebaceous lipogenesis, normalizes the pattern of keratinization within the sebaceous gland follicle, inhibits inflammation, and – in a secondary manner – reduces growth of P. acnes. It is most active in the treatment of severe recalcitrant nodulocystic acne and in the prevention of acne scarring

Anti-Acne Drugs, Examples Topical antibiotics including 2% erythromycin, 1% clindamycin, or a combination of 3% erythromycin and 5% benzoyl peroxide may be used in patients with an inflammatory component These agents decrease colonization of the skin by P. acnes and may also inhibit neutrophil chemotaxis. However, resistant P. acnes has been documented For this reason, monotherapy with topical or systemic antibiotics is discouraged. The concurrent use of topical benzoyl peroxide has been shown to inhibit and decrease resistance Individuals with sensitive skin present a special therapeutic challenge and may benefit from sulfacetamide products or azelaic acid cream, which may also decrease postinflammatory hyperpigmentation Azelaic acid has comedolytic and antibacterial properties and may be synergistic with retinoids Oral antibiotics (e.g., tetracycline, minocycline, doxycycline, erythromycin) can be used when wide distribution of lesions makes topical therapy impractical

Anti-Warts Drugs

Anti-Warts Drugs, Introduction Cutaneous warts are benign epidermal proliferations caused by human papillomavirus (HPV) infection Papillomaviruses comprise a family of viruses that are host-species specific. Thus, HPV causes disease only in humans, infecting epithelial tissues and mucous membranes Cutaneous warts are one of the most common skin conditions affecting children Transmission of warts occurs from direct person-to-person contact or indirectly by fomites Swimming pools and bathrooms are common areas for the spread of warts if the skin is macerated and touches rough surfaces Once HPV has infected the skin, autoinoculation can occur by scratching, shaving or traumatizing the skin Previously infected patients have a higher risk for development of new warts than those never infected Nongenital warts occur in 7% to 10% of the general population, with the incidence peaking between the ages of 12 and 16 years Warts occur equally in both sexes and are among the three most common dermatoses treated Owing to natural immunity, approximately 23% of warts regress spontaneously within 2 months, 30% within 3 months and 65% to 78% within 2 years The rate of clearance is influenced by factors such as viral type, host immune status, extent and duration of warts

Anti-Warts Drugs, Introduction Verruca vulgaris (common warts) are hyperkeratotic, exophytic and dome-shaped papules or nodules especially located on fingers, hands, knees, elbows or any other sites of trauma. Generally, they are asymptomatic but sometimes cause mild pain The clinical picture of cutaneous warts differs by specific location on the body: Plane or flat warts are smooth flat topped papules with minimal scaling and only slight elevation, most often on the face. They are more common in children and young adults. They generally cause no symptoms but can be difficult to treat Plantar warts are warts on the sole of the foot They can be painful due to their callused, endophytic papules that have deeply penetrating sloping sides and a central depression Numerous coalesced warts on the plantar surface will form a tile-like pattern known as mosaic warts. As with other plantar warts, they are often tender

Anti-Warts Drugs, Introduction Filiform warts are long, frondlike growths usually on the eyelids, face, neck, or lips. They are usually asymptomatic. This morphologically distinct variant of the common wart is benign and easy to treat Periungual warts appear as thickened, fissured cauliflower-like skin around the nail plate. Patients frequently lose the cuticle, and are susceptible to paronychia. These warts are more common in patients who bite their nails Anogenital warts occur in the perineum and on the genitalia or in the genital tract and are one of the most common sexually transmitted diseases. They are generally asymptomatic Although > 90% of anogenital warts resolve within 2 years, persistent infection with high-risk HPV subtypes is the main cause of cervical cancer

Treatment of Warts The American Academy of Dermatology developed criteria for the indications for wart treatment including: the patient’s desire for therapy symptoms of pain, bleeding, itching or burning disabling or disfiguring lesions large numbers or large sizes of lesions the patient’s desire to prevent the spread of warts to unblemished skin of self or others an immunocompromised condition Anogenital warts should receive special consideration and warrant vigilance for other sexually transmitted diseases Extragenital warts in people who are immunocompetant are harmless and usually resolve spontaneously within months or years owing to natural immunity In view of this, a policy of not treating them is often advised. However there is considerable social issues associated with warts on the face and hands, and they can be painful on the soles of the feet and near the nails. Therefore, many patients request treatment for their warts

Treatment of Warts, contd. Salicylic acid (SA) is a first-line therapy for warts It is a keratolytic therapy with a mechanism of action that slowly destroys virus-infected epidermis and may cause an immune response from the mild irritation caused by the salicylic acid It is prepared in concentrations from 10% to 70%. Over-the-counter preparations are available as 17% SA combined in a base of flexible collodion or as a 40% salicylic acid plaster patch The advantages of over-the-counter SA include convenience, minimal expense, negligible pain and reasonable effectiveness Disadvantages are that results require weeks to months of treatment, and the patient must strictly adhere to instructions Side effects can include occasional contact dermatitis due to colophony in the collodion base. There is also a potential risk of systemic toxicity in children that can be avoided if lower concentrations or limited areas of treatment are used Plantar warts may be more amenable to treatment with SA with occlusion than hand warts Wart paints should not be used to treat facial warts because of severe irritation and a potential for scarring Monotherapy with 5-fluorouracil, benzalkonium or cryotherapy proved no more effective than SA-containing paints