Toxic epidermal necrolysis after sun-exposure probably due to lamotrigine and chlorpromazine

Photodistributed Stevens-Johnson syndrome and toxic epidermal necrolysis: a systematic review and proposal for a new diagnostic classification

BACKGROUND

Ultraviolet radiation (UVR) exposure is commonly reported as a risk factor for Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). However, minimal evaluation of photo-induced SJS/TEN has been conducted. Thus, this review identifies all cases of SJS/TEN that are linked to an acute exposure of UVR and outlines the unifying characteristics of these cases. Furthermore, the theoretical pathogenesis, differential diagnoses, and proposed diagnostic criteria are defined.

METHODS

PubMed, Google Scholar, and other databases and websites were searched from inception to September 2021 to identify studies that met inclusion criteria. The following keywords were utilized: "Stevens-Johnson syndrome" and "toxic epidermal necrolysis" with "ultraviolet," "photodistributed," "photo-induced," "photosensitivity," and "photo." One reviewer assessed study characteristics, with confirmation by a second. The risk of bias was assessed independently by another.

RESULTS

Thirteen patient cases were identified, all reporting ultraviolet radiation prior to rash onset and an underlying causal drug. Case classifications included 7/13 SJS and 6/13 TEN. All cases described the rash as photodistributed with UVR exposure prior to rash onset (delay of 1-3 days) and a causal drug. 10 cases provided evidence that the photodistributed rash lacked linear demarcation (as in a sunburn) with satellite target-like lesions. No cases described a flu-like prodrome.

DISCUSSION

Mucositis, palmar and plantar rash, a positive Nikolsky sign, and a prolonged disease course can help distinguish from photosensitive reactions, while a negative direct immunofluorescence test is important to distinguish from other photo-induced disorders.

CONCLUSION

Physicians should be aware that UVR may precipitate SJS/TEN in patients taking susceptible drugs. After a 24-h delay from UVR exposure, a non-distinct, photodistributed rash appears with no flu-like prodrome and progresses for at least 48 h to include vesiculobullous eruptions and mucous membrane involvement. Photodistributed SJS/TEN appears to be photo-drug-induced with a unique onset and rash presentation that should be recognized as a distinct diagnosis.

Rash during lamotrigine treatment is not always drug hypersensitivity: A retrospective cohort study among children and adults

Purpose Cutaneous adverse drug reactions (cADRs) are a major cause of lamotrigine (LTG) discontinuation. Remarkable variation in their reported incidence suggests confounders and diverse terms and definitions. The aim of this study was to identify immunological cADRs and to throw light on classification and differential diagnoses in children and adults. Methods Hospital records of 2683 patients with epilepsy (1897 adults, 786 children) were retrospectively screened. Of these, 403 patients (236 adults, 167 children) with first time exposure to LTG were reviewed. Skin reactions were categorized into possible or probable cADRs due to LTG hypersensitivity, and other skin reactions (OSRs) unlikely to be caused by this mechanism. Results 29 of 403 patients (7.2%) reported emergent skin symptoms within 3 months of treatment with LTG of which 20 (5%: 5.9% adults, 3.6% children) were categorized as possible or probable cADRs. Concomitant infection appeared to be present in several cases, particularly in children. OSRs were found in 4.2% of the children using LTG, compared to 0.8% of the adults (p = 0.04). Conclusions Rash during the early phase of LTG treatment is not always drug hypersensitivity. Whenever skin symptoms occur, other potential causes should receive attention to avoid needless discontinuation, particularly in children. However, when early symptoms and signs of severe cADRs are suspected, LTG should promptly be discontinued.

Enhanced photo(geno)toxicity of demethylated chlorpromazine metabolites

Chlorpromazine (CPZ) is an anti-psychotic drug widely used to treat disorders such as schizophrenia or manic-depression. Unfortunately, CPZ exhibits undesirable side effects such as phototoxic and photoallergic reactions in humans. In general, the influence of drug metabolism on this type of reactions has not been previously considered in photosafety testing. Thus, the present work aims to investigate the possible photo(geno)toxic potential of drug metabolites, using CPZ as an established reference compound. In this case, the metabolites selected for the study are demethylchlorpromazine (DMCPZ), didemethylchlorpromazine (DDMCPZ) and chlorpromazine sulfoxide (CPZSO). The demethylated CPZ metabolites DMCPZ and DDMCPZ maintain identical chromophore to the parent drug. In this work, it has been found that the nature of the aminoalkyl side chain modulates the hydrophobicity and the photochemical properties (for instance, the excited state lifetimes), but it does not change the photoreactivity pattern, which is characterized by reductive photodehalogenation, triggered by homolytic carbon-chlorine bond cleavage with formation of highly reactive aryl radical intermediates. Accordingly, these metabolites are phototoxic to cells, as revealed by the 3T3 NRU assay; their photo-irritation factors are even higher than that of CPZ. The same trend is observed in photogenotoxicity studies, both with isolated and with cellular DNA, where DMCPZ and DDMCPZ are more active than CPZ itself. In summary, side-chain demethylation of CPZ, as a consequence of Phase I biotransformation, does not result a photodetoxification. Instead, it leads to metabolites that exhibit in an even enhanced photo(geno)toxicity.

Lamotrigine-induced severe cutaneous adverse reaction: Update data from 1999-2014

We systematically reviewed and analyzed published patients with Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) associated with lamotrigine therapy to identify characteristics of these reactions. We identified a total of 70 patients (42 SJS, five SJS/TEN, 23 TEN). The female to male ratio was 2.83:1 in the TEN group and 1.47:1 in the SJS group. Patients in the TEN group were younger than in the SJS group but this difference was not significant (28.35 versus 32.71 years, respectively; p=0.27). The median time to onset was 25.33 versus 18.42 days for SJS and TEN, respectively. The median dosage at onset was 36.46 versus 57.29mg, and final dosage 111.25 versus 97.92mg/day for SJS and TEN, respectively. The median final dosages did not significantly differ. Concomitant use of valproate acid was reported in 54.55% of the SJS patients and 50.00% of the TEN patients. Three fatal reactions were reported, of which two patients deteriorated rapidly and died within 12h of admission, indicating that this disease can develop rapidly before effective treatment. There was no significant difference between the SJS and TEN groups in any of the clinical factors examined which confirmed the opinion that SJS and TEN are part of a single disease spectrum.