Author's reply

BB Mahajan

 Professor, Dermatology, Venereology and Leprosy, Govt. Medical College, Amritsar, Punjab, India

Correspondence Address:
B B Mahajan
Professor, Dermatology, Venereology and Leprosy, Govt. Medical College, Amritsar, Punjab
India

Sir,

Regarding first query:

Therapeutic efficacy of a drug is defined as the maximum response of a drug irrespective of the drug concentration.^[1],[2] So, the concentration of a drug in relation to its half-life should not be taken into consideration for its therapeutic efficacy.

In our study, intramatricial injection of these drugs corrects the defective keratinization at the level of nail matrix and the response is visualized and evaluated on the finger nail plate that grows at a rate of 3 mm/month, taking a total of 24 weeks.

All the drugs used are not depot agents; hence the therapeutic efficacy of these drugs in nail psoriasis should not be related to elimination pharmacokinetics.

Regarding second query:

Koebnerization can occur in nail psoriasis, as commonly observed in certain occupations such as manual laborers, typists, farmers and housewives who are exposed to repeated nail trauma. Hence, physical trauma such as nail biting, nail picking, manicure, wearing tight shoes, clearing subungual debris are discouraged in nail psoriasis.^[3],[4]

Although, reverse koebnerization in nail psoriasis has not been reported in the literature till date, yet further studies are required to compare the efficacy of intramatricial injection therapy with that of the needle tip trauma to the nail matrix alone, without injecting any drug. With needle tip injury, both koebnerization and reverse koebnerization are theoretically possible, but needs to be substantiated by further studies.

Regarding third query:

In our study, two injections of the respective drugs have been given 6 weeks apart, which has possibly only corrected the defective keratinization of nail matrix rather than causing the growth arrest of the nail matrix as a whole resulting in Beau's lines.

The chances of appearance of Beau's lines may increase with weekly injections rather than giving two injections 6 weeks apart.

To conclude, we highly appreciate the queries and postulate that intramatricial injection of a drug should be recommended at 6 weeks' intervals rather than at more frequent intervals to maximize their efficacy and minimize the adverse effects in psoriatic finger nails.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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