Publications on bufexamac-induced ACD mainly consist of international reports, as this medication has been discontinued in the United States. Bufexamac is a highly sensitizing agent that can lead to severe polymorphic eruptions requiring treatment with prednisolone and even hospitalization.58 In one Australian case report, a mother developed an edematous, erythematous, papulovesicular eruption on the breast while breastfeeding her baby, who was being treated with bufexamac cream 5% for infantile eczema.59 Carprofen-induced photoallergic contact dermatitis is associated with occupational exposure in pharmaceutical workers.60,61 A few case reports on other nonsteroidal anti-inflammatory drugs, including etofenamate and aceclofenac, have been published.62,63
Compounded Medications—Compounded topical analgesics, which help to control pain via multiple combined effects, have gained increasing popularity in the management of chronic neuropathic pain disorders. Only a few recent retrospective studies assessing the efficacy and safety of these medications have mentioned suspected allergic cutaneous reactions.62,63 In 2015, Turrentine et al64 reported a case of ACD to cyclobenzaprine in a compound containing ketamine 10%, diclofenac 5%, baclofen 2%, bupivacaine 1%, cyclobenzaprine 2%, gabapentin 6%, ibuprofen 3%, and pentoxifylline 3% in a proprietary cream base. When patients present with suspected ACD to a compounded pain medication, obtaining individual components for patch testing is key to determining the allergic ingredient(s). We suspect that we will see a rise in reports of ACD as these topical compounds become readily adopted in clinical practices.
Patch Testing for Diagnosis
When patients present with symptoms concerning for ACD to medicaments, the astute clinician should promptly stop the suspected topical medication and consider patch testing. For common allergens such as neomycin, bacitracin, or ethylenediamine, commercial patch test preparations exist and should be used; however, for drugs that do not have a commercial patch test preparation, the patient’s product can be applied as is, keeping in mind that certain preparations (such as retinoids) can cause irritant patch test reactions, which may confound the reading. Alternatively, individual ingredients in the medication’s formulation can be requested from the manufacturer or a compounding pharmacy for targeted testing. Suggested concentrations for patch testing based on the literature and expert reference are listed in the Table. The authors (M.R., A.R.A.) frequently rely on an expert reference66 to determine ideal concentrations for patch testing. Referral to a specialized patch test clinic may be appropriate.
Final Interpretation
Although their intent is to heal, topical medicaments also can be a source of ACD. The astute clinician should consider ACD when topicals either no longer seem to help the patient or trigger new-onset dermatitis. Patch testing directly with the culprit medicament, or individual medication ingredients when needed, can lead to the diagnosis, though caution is advised. Stay tuned for part 2 of this series in which we will discuss ACD to topical steroids, immunomodulators, and anesthetic medications.