Challenges of Topical Medication Use in PN

Raj Chovatiya, MD, PhD, reviews the limitations of topical treatments when managing PN.

Raj Chovatiya, MD, PhD: I might toss it back over to you, Dr Shawn Kwatra, MD. Another one of those areas that people end up exploring is, how can I take some of these systemic therapies and potentially put them in a topical format and get some use out of them? We know that there’s been an explosion of compounds in pharmacies. A lot of these things are in solution, whether it be topical versions of gabapentin, amitriptyline, ketamine combinations that are out, you name it. Have you found any success out there in some of the compounding solution-based approaches?

Shawn Kwatra, MD: I have, but not as much for prurigo nodularis [PN]. I think it’s harder to penetrate the nodule and get to the area of inflammation. I use many topical compounded agents with gabapentin, lidocaine, amitriptyline, and ketamine. Mostly neuropathic itch. I’m using that for brachial radius pruritus, nostalgic peristatic, and scalp pruritus even in a solution form. When I’ve tried them in prurigo nodularis, I’ve found that it’s not at the target site. It’s not able to work as well. Also, many folks have so many nodules, it’s hard to get the drug to the right spots. Like Dr Sarina B. Elmariah mentioned, we know that there’s also itching in these patients in the nonlesional skin. We asked and two-thirds of patients said the itch is in the nodules and in the nonlesional appearing skin. We know there’s subclinical inflammation in those skin types. There’s more coiling of the nerves in those skin types. To me, it’s really rare to have PN that doesn’t need a systemic agent.

Sarina B. Elmariah, MD, PhD: Yes. I also just want to highlight that compounding medications, while great, really has to be a limited Band-Aid for the access reasons. Also, access in the sense that it’s quite expensive and it’s often not covered by insurance. Quite frankly, they’re really not the best solution for many patients. If they have few numbers and you can keep the amount small that you’re prescribing, it can be beneficial to some patients. I look at it just like giving a topical steroid. You’re not only going to have a harder time accessing the depth of that lesion, but again, just getting patients to even be able to get that and apply it everywhere, it’s really a challenge. It can be used, I think, as a localized Band-Aid for individual lesions that are particularly problematic, not as an overall strategy.

Raj Chovatiya, MD, PhD: I’m curious in exploring this with you just knowing how much we use topicals as dermatologists, it’s very interesting to hear how we all feel about it. What has been your success? I’ll start with you Dr Shawn Kwatra, in terms of if you’re really going for someplace regional. Maybe there are a lot of ulcerations or erosions using occlusion using a new Unna boot, and getting it to places where patients can scratch but you’re also treating the itch. Do you feel like that helps to increase the penetration and/or efficacy of topicals that otherwise aren’t doing the trick?

Shawn Kwatra, MD: It’s a great question. One of the things we use is steroids impregnated in tape in occlusion. I think if you do that, you can get better steroid penetration or even if you use plastic wrap. Just to tie those areas, I think that can help a lot. The problem is having so many. As you said, as a regional therapy, occlusive dressings can help. I contend that in this disease more than any others, if someone gets Unna booted, in some ways, I view that as torture because they have unresolved inflammation that’s causing this itch, and we’re saying you can’t scratch those areas, but then we don’t give systemic therapies. If you purely Unna boot it, I just am not a fan of it. Overall, I know that some folks do it, but honestly I think if you Unna boot someone and they have unresolved inflammation that’s going on, you’re really torturing someone, so I try to stay away from doing that.

Sarina B. Elmariah, MD, PhD: It’s interesting because you are addressing part of the itch-scratch cycle that is so inherent to PN. However, you are not addressing the itch, necessarily. Now, I will say that there are some patients who have asked me for Unna boots, or a cast on their arm, or one person asked me for a body cast. And, while we did not pursue that, there are isolated patients where, for example, injecting a steroid or putting on a topical, and then somehow occluding it, whether it be with a tape or even an Unna boot, can be helpful. But I think those patients are few and far between, and it really takes a discussion with patients.

I think it’s like the way we used to think about treating psoriasis. We were happy to just give people a steroid, but we knew we weren’t really addressing the depth of their disorder. And now that we have so many options, it’s easy to try to really address the spectrum of disease that is psoriasis. And that same thing is happening with atopic dermatitis, and I feel that that should be our goal. And it really is our goal with prurigo nodularis, that we start to think about this as being a deeper disorder, that we can address through multiple systemic medications. Quite frankly, I think sedating and even nonsedating antihistamines can be much more detrimental to many people than some of the drugs that we use to treat PN and some of these other disorders. So, it’s really just a matter of perspective and how you view the disease, in order how to figure out how you’re going to treat it.

Transcript edited for clarity

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