Follicular skin diseases
Oral therapy key points test
To make sure you have understood the key points of this section, choose the best option(s):
First-line antibiotics suitable for treating acne include:
* Penicillin V
Explanation: The tetracycline group of antibiotics are most often prescribed. P acnes is now frequently resistant to erythromycin (10 - 90% depending on the country studied). Other antibiotics, including trimethoprim, alone or in combination with sulfamethoxazole, and azithromycin, are reportedly helpful.
Which of the following statements is true?
* Oral antibiotics should be used to treat acne for no more than six months
*! Antibiotics have anti-inflammatory action
* Tetracyclines have no effect on _Proprionibacterium acnes_
* The most effective combination for acne is minocycline with topical clindamycin
Explanation: Antibiotics suitable for treating acne have anti-inflammatory properties and are effective against _Propionibacterium acnes_. There is no benefit to adding topical antibiotics if the patient is already on oral antibiotics; instead a keratolytic/comedolytic agent such as benzoyl peroxide or a topical retinoid should be prescribed. Prolonged courses (up to several years) of antibiotics are often prescribed for acne, but increasingly patients requiring ongoing systemic treatment are referred to a dermatologist for isotretinoin.
Other chronic skin diseases routinely treated with antibiotics include:
#! Bullous pemphigoid
# Pityriasis versicolor
Explanation: Other chronic skin diseases routinely treated with antibiotics include folliculitis, bullous diseases, granulomatous diseases and other diverse inflammatory diseases.
Common (>1%) adverse effects of tetracyclines include:
# Staining of teeth in adults
Explanation: Tetracyclines commonly cause oesophagitis, photosensitivity and candidiasis. They should be avoided in young children because of permanent staining of dental enamel. There are many rare adverse reactions including temporary staining of the teeth in adults.
Isotretinoin may have the following adverse effects:
# Reduces efficacy of oral contraceptive
Explanation: Isotretinoin common causes mucocutaneous dryness which may result in dermatitis, keratitis, epistaxis and secondary infection. It has no effect on oral contraceptive efficacy and it does not cause thromboembolic disease.
Oral contraceptives suitable for acne in females:
* Must contain cyproterone to be effective
* Include progestogen-only pills
*! Should not be used for acne if there are significant risk factors for thromboembolic disease
* Should be avoided in those on spironolactone
Explanation: Several low-dose combined oral contraceptives are helpful for acne in females. Progesterone-only pills are not effective. However, oestrogen-containing contraceptives may result in thromboembolism in predisposed females, and the risk is greater for the combination of cyproterone acetate and ethinyl oestrodiol than for second generation pills. Spironolactone may be prescribed alone or combined with an oral contraceptive agent.
Which of the following is unsuitable treatment for moderate acne?
* Isotretinoin capsules
* Doxycycline capsules
*! Finasteride tablets
* Ethinyl oestrodiol/cyproterone acetate tablets
Explanation: Moderate acne is treated with topical keratolytic agents and oral antibiotics, or oral retinoids, and in females, with relatively anti-androgenic oral contraceptive agents. Finasteride is not used for this indication but may be prescribed for androgenetic hair loss in males.