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May 1996 Volume 1 Number 5
Azelaic acid is a saturated dicarboxylic acid found naturally in wheat, rye and barley. It is effective against a number of skin conditions when applied topically in a cream formulation of 20%. Azelaic acid is now sold in more than 50 countries, including those of western Europe. It was approved in the USA in September 1995, but is still awaiting approval in Canada.
Topical azelaic acid has similar efficacy to topical benzoyl peroxide gel 5%, tretinoin cream 0.05%, erythromycin cream 2%, and oral tetracycline 0.5 to 1 g/day, in the treatment of comedonal and mild to moderate inflammatory acne. However, it was less effective than oral isotretinoin for the treatment of conglobate acne1,2 Azelaic acid cream should be applied twice daily for at least 2 - 3 months and can be used for up to one year. Improvement should be detectable within 1 - 2 months.3 To ensure adequate drug penetration, the cream should be rubbed thoroughly (but not too vigorously) into cleansed skin for 2 - 3 minutes.
Although confirmation is needed, preliminary clinical studies suggest that azelaic acid is effective in the treatment of melasma. Some data suggest that topical azelaic acid, used twice daily in conjunction with a broad spectrum sunscreen, is as effective as 4% and more effective than 2%, hydroquinone creams.1,2
Safety During Pregnancy and Lactation
No teratogenic effects have been demonstrated following oral administration to animals. If azelaic acid cream is used during pregnancy, systemic absorption is likely to be less than that resulting from diet.
Azelaic acid is very well tolerated and seems devoid of overt systemic effects when applied topically. Nonetheless, as with any drug product, there is potential for an allergic response. Mild transient erythema and cutaneous irritation characterized by scaling, pruritus, and a mild burning sensation have been reported by 5 - 10% of patients, usually subsiding after 2 - 4 weeks of treatment.1,2 Photosensitization has been rare.3
|"Clinical experience over the last six years shows that the drug is active and provides clearing, which becomes increasingly apparent over four to six months."|
|Prof. Ruggero Caputo,
Istituto di Scienze
Dermatologiche, Milan, Italy
|"Although clinical experience in the USA is limited, it would appear that this agent may be effective, but may take as long as six months to achieve worthwhile clearing."|
|Prof. Alan Shalita,
Department of Dermatology,
SUNY Health Sciences Center, Brooklyn, USA.
Mechanism of Action
Azelaic acid displays bacteriostatic and bactericidal properties against a variety of aerobic and anaerobic micro-organisms present on acne-bearing skin. It also has an antikeratinization effect. The antiproliferative/cytotoxic effects of azelaic acid seem to be mediated primarily via disruption of mitochondrial respiration and/or cellular DNA synthesis.
Percutaneous absorption varies with the formulation. In one study, about 3.6% of the drug was absorbed following application of 1g of a 20% cream.4
Clinical Assessment of Azelaic Acid
Azelaic acid is probably as effective as topical treatment with tretinoin, benzoyl peroxide, erythromycin, or tetracycline in comedonal or papulopustular acne, but is less effective than oral isotretinoin in conglobate acne.1,2 It may be as effective as hydroquinone cream 4% in treating melasma,1,2 but further studies are needed. Azelaic acid has demonstrated long-term safety and lack of toxicity.
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|Class||Name/Company||Approval Dates and Comments|
|Approved by the FDA, December 6, 1995 for use in combination with approved nucleoside analogues for the treatment of advanced HIV infection in selected patients. It was not recommended for monotherapy. The recommended dose of saquinavir is 600 mg tid. This drug was the first protease inhibitor to be approved.|
|Ritonavir was approved on the March 1, 1996, just 72 days after the application was filed. Ritonavir is approved in combination with nucleoside analogues or as monotherapy for the treatment of HIV infections when therapy is warranted.|
|Indinavir was approved by
the FDA (March 13, 1996) in 42 days, the shortest
approval time ever. It is approved for the treatment of
HIV infection in adults when antiretroviral therapy is
warranted. Indinavir is also the first protease inhibitor
to be approved for market distribution in Canada.
|Mupirocin calcium ointment
2% (Bactroban Nasal®) has recently been approved by the
FDA (see Issue 3). Mupirocin ointment 2% (Bactroban®)
has just been approved in India.
|This new vitamin D3
analogue, first marketed in Japan by Teijin, has now been
licensed by Merck KGaA and has been introduced into
Switzerland and the UK. Tacalcitol need only be applied
once daily. Due to absorption of tacalcitol, treatment
should be limited to two eight-week courses a year.
|This month (May 1996), the
FDA approved terbinafine as a treatment for
onychomycosis. In Canada and many other countries,
terbinafine is already available for this indication.
Toenails are tre ated for 12 weeks, and fingernails for
six weeks. Terbinafine can be given once daily, with or
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