Ketoconazole does not decrease fungal amount in patients with seborrhoeic dermatitis

This study examined in vivo (carried out on actual patients) effects of ketoconazole on the malassezia fungal populations of human skin. 6 healthy individuals and 6 individuals with seborrheic dermatitis where examined over a 2 month period.

General Points

• Antifungal therapy is consider as one of the most effective ongoing treatment options for seborrheic dermatitis. And ketoconazole is one of the most popular options.
• Though Ketoconazole’s antifungal properties have been demonstrated in vitro (lab tests), in vivo (studies on real test subjects) are sparse.

Approach

• Individuals with seborrheic dermatitis used a 2% ketoconazole, 1% salicylic acid shampoo every other day over the two month period.
• Healthy subjects did not undergo treatment.

Outcome

• Out of a total of 104 analyzed samples during the 2 month period, Malassezia globosa was found in all samples and Malassezia restricta was found in 88 samples.
• Fungal amounts were quite stable for the health subjects.
• Fungal amounts had significant variation during the 2 months for the individuals affected by seborrheic dermatitis.
• Fungal amounts did not decrease on the skin of SD affected individuals and in some cases an increase was noted.
• All individuals with seborrheic dermatitis showed symptom improvement after only the first month, irrespective of fungal population changes.

Additional Notes

• Study mentioned two other papers which reported Candida albicans gene expression shift under ketoconazole and zinc pyrithione.
• Possible non-antifungal mechanism for symptom improvement may include:
  • Shift of fungal gene expression
  • Shift of host gene expression
  • Suppression of inflammatory response
  • Increase of anti-inflammatory response

Summary

Ketoconazole is an antifungal agent often prescribed for the treatment of seborrheic dermatitis. Initially it may seem that it’s antifungal potential is what causes symptom improvement.

This small scale study demonstrated that fungal populations do not appear to be affected by regular ketoconazole. However, symptom improvement occurs regardless of this fact.

Research Paper Details