Topical clobetasol propionate, zinc sulfate

Bhushan Kumar, Kamaldeep Sandhu

 Department of Dermatology, Venereology and Leprology, PGIMER, Chandigarh-160 012, India

Correspondence Address:
Bhushan Kumar
Department of Dermatology, Venereology and Leprology, PGIMER, Chandigarh-160012
India

Sir,

We read with great interest the article entitled "A double blind randomized multicentre controlled study of topical 0.05% clobetasol propionate with 2.5% zinc sulfate preparation" by Thomas et al (Indian J Dermatol Venereol Leprol 67:135-137;2001). We would like to make a few comments in relation to this study.

First, is regarding the inclusion of patients with clinically unrelated dermatoses like psoriasis, eczema, prurigo nodularis and contact dermatitis in order to compare the two treatment modalities. The term chronic lichen planus (LP) has been used which is not mentioned in standard textbooks though it is well known that lichen planus tends to follow a chronic, relapsing course. Mucosal,hypertrophic and lichen planopilaris varieties of LP are known to follow more protracted unremitting course.[1],[2] Unfortunately detail regarding the varieties of lichen planus, which were included, is completely omitted. Except for psoriasis the extent of the cutaneous lesions and the number of lesions taken up for comparison in these disorders has not been mentioned.

Secondly in the preliminary assessment, the severity of the disorders was graded on a scale of 0-3 including four parameters viz erythema, lichenification, scaling and itching. All these four parameters are not universal to all the dermatoses included in the study and so cannot be applied to assess the severity of lesions with different characteristics. It is hard to understand how lichenification could be used to assess the severity of disease in patients with psoriasis. Similarly scaling and erythema do not form important part of either prurigo nodularis or lichen planus.

Chronic dermatoses like prurigo nodularis, subacute and chronic eczemas are best treated with an ointment formulation instead of a cream base, which has been utilized in the study. We are not very sure regarding the biovailability of this topical formulation combining clobetasol and zinc sulfate as in a study, percutaneous absorption and bioavailability of zinc from zinc sulphate preparations was found to be less when compared with other preparations like zinc 2- pyrrolidone 5-carboxylate.[2]

It has not been mentioned in the methodology whether the patients in both the groups were age and sex matched beforehand although the results show no difference in this regard between the treatment groups. It has been mentioned that 57.25% patients treated with clobetasol propionate and zinc sulfate combination showed complete recovery by day 28 as compared to 37.6% in the other treatment group. These results give the collective/clubbed response of all the dermatoses. It would have been better for understanding purposes if the responses in the individual disorders had been highlighted. Moreover the end results are given at day 28 and chronic dermatoses like prurigo nodularis and lichen planus are less likely to respond so dramatically in 4 weeks time. This would have been clear if response rates in individual disorder had been provided.

Lastly, the exact mode of action of zinc has not been elucidated. We are giving below little more details for the benefit of the readers. Zinc sulphate not only has anti-inflammatory action by blocking the cytokines but it also causes induction of apoptosis.[3] Zinc has been shown to have a protective effect on keratinocyte activation markers like ICAM-1 and TNF- secretion stimulated by INF-y.

Thus we conclude that if the above mentioned points had been taken into consideration during the planning of the study, the results would have had been more comprehensive of use to readers.

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