In this installment of Dermbusters, Dr. Nick Brownstone sits down with Dr. G. Michael Lewitt to get his thoughts on blood monitoring for patients prescribed biologics and to discuss how he advises patients who believe tretinoin must be applied at night. 

Do dermatologists have to check CBCs and LFTs with all biologics? 

Dr. Lewitt explains that from looking at the data, it’s likely not necessary to monitor CBCs and LFTs for patients who are prescribed a biologic. He estimates that half of the biologic prescribers across the US do this type of monitoring for patients taking a biologic, and the other half do not. 

He recalls that when the IL-17s came out, there were a few incidences of neutropenia and leukopenia observed which led to a trend of blood monitoring every 6 months; however, he then found he did not see any more abnormalities across the following 2 years and felt that as a result, this type of monitoring was wasting his time and patients’ healthcare funds. He now checks CBCs and LFTs annually for patients taking a biologic. 

When counseling his patients on this topic, he emphasizes to them that they have a chronic skin condition and should receive age- and disease-state-appropriate blood monitoring, like TSH and fasting limit profiles, at intervals recommended by their primary care physicians. 

In sum, he emphasizes that the necessity of checking CBCs and LFTs for patients taking a biologic is largely a myth. 

Do topical retinoids have to be applied at night? 

Dr. Lewitt explains that of the 4 current generations of retinoids, the original tretinoin and tretinoin derivates were photolabile, while generations 2 though 4 are photostable. Historically, patients were encouraged to apply retinoids at night because as soon as they were exposed to sun in the morning, the medication became inactivated. 

Even though the newer generations of retinoids are photostable, Dr. Lewitt still prefers nighttime application. With the most common side effect being retinoid dermatitis or irritation, he finds that with evening application, he can then troubleshoot in the mornings to ensure there isn’t any scale appearing on his nose or eyes. However, from a pharmacodynamic standpoint, generations 2 though 4 do not need to be applied at night. 

He advises his patients that the best time to apply it is whenever they can best remember and recommends applying it at the same time they brush their teeth to establish a routine.