MAUI, HAWAII (FRONTLINE MEDICAL NEWS) If you’re going to prescribe apremilast for psoriasis or psoriatic arthritis – and more and more physicians are doing so because of the drug’s exceptional safety profile – you’d better get familiar with the oral phosphodiesterase-4 inhibitor’s gastrointestinal side effects, Dr. George M. Martin advised at the 2016 Rheumatology Winter Clinical Symposium.

“One of the biggest hurdles we have to deal with when we prescribe apremilast is the fact that there are these GI side effects,” said Dr. Martin , a dermatologist practicing in Maui and codirector of the rheumatology symposium.

Celgene, which markets apremilast (Otezla), sponsored an analysis of the pattern of diarrhea that emerged in the pooled results of the phase III ESTEEM 1 and 2 trials of apremilast at 30 mg twice daily for psoriasis and the PALACE 1-3 phase III psoriatic arthritis trials.

Diarrhea occurred in 16%-18% of patients on apremilast, a rate roughly threefold greater than in placebo-treated controls. Diarrhea onset was usually within the first 14 days of therapy. When it occurred, the duration was typically about 2 weeks.

“This you can relay to your patients so they’re not surprised if it happens,” the dermatologist said.

It’s a secretory diarrhea, and it is believed to be a classwide effect for the phosphodiesterase-4 (PDE-4) inhibitors. For example, roflumilast (Daliresp), an oral PDE-4 inhibitor used in the treatment of chronic obstructive pulmonary disease, has the same diarrhea issues. The mechanism has been worked out: The drug increases intracellular cyclic adenosine monophosphate, with resultant activation of chloride channels in crypts in the small bowel, which in turn leads to secretion of chloride ions. It takes the large bowel a couple of weeks to adapt. Caffeine causes diarrhea in some individuals through a similar mechanism.

Apremilast-related diarrhea often responds to the time-tested OTC remedies, including bismuth salicylate or fiber supplements. Alternatively, Dr. Martin said he is a fan of the oral prescription agent crofelemer (Fulyzaq) because of its exceptional safety, tolerability, and effectiveness. Plus, many residents of the garden islands of Hawaii like the idea of using a botanical derived from the latexlike sap – known as ‘dragon’s blood – of a South American tree. Crofelemer’s approved indication is the treatment of diarrhea associated with anti-HIV agents.

Diphenoxylate/atropine (Lomotil) is another effective prescription option.

Nausea and/or vomiting occurred in 15%-17% of apremilast-treated patients in the phase III trials. As with diarrhea, if nausea and/or vomiting is going to happen, it occurs early, within the first week or two. Dr. Martin said he finds in his own practice that the nausea/vomiting is less bothersome for patients than the diarrhea. Drug discontinuation due to any GI side effects is rarely necessary.

The nausea/vomiting is usually readily managed by encouraging affected patients to make sure that they’re well hydrated, take their apremilast with food, and eat smaller, more frequent meals. OTC diphenhydramine (Benadryl) is often effective, as are the usual prescription antiemetic agents.

Pharmaceutical industry data indicate apremilast has quickly captured a 17% share of the market for systemic psoriasis therapies. There is a good reason for that, according to Dr. Martin: “Dermatologists have historically been risk averse. And apremilast is arguably the safest systemic agent we have to treat psoriasis. The beauty of apremilast is it requires no laboratory monitoring. That makes it attractive to dermatologists who are concerned about systemic therapy. It’s why there has been a huge jump in adoption of apremilast.”

Apremilast is comparable to methotrexate in terms of efficacy as reflected in week 16 PASI-75 response rates of about 35%, meaning 35% of treated patients obtain at least a 75% improvement in Psoriasis Area and Severity Index scores, he continued. Apremilast is particularly effective for scalp and nail psoriasis, making it a good option for patients who have psoriasis at those sites but not extensive involvement elsewhere, which might call for the use of a more potent biologic agent.

Surveys indicate that 20% of dermatologists write 80% of all prescriptions for biologic agents used to treat psoriasis. The thinking was that apremilast would appeal to the 80% of dermatologists who have steered clear of the biologics, and that after becoming comfortable with apremilast, they might become more receptive to using biologics for their patients with an inadequate response to the oral PDE-4 inhibitor. That hasn’t happened yet.

“We’re not seeing apremilast function as the gateway drug we thought it would be. It’s just going to take some time for those prescribers either to refer their patients who aren’t getting a good response to the next doctor who’s more adept at treating with biologic agents, or perhaps they themselves will get more involved,” Dr. Martin predicted.

He reported serving on scientific advisory boards for, and/or as a consultant to, nine pharmaceutical companies.