Genetic Association of Co‐Trimoxazole‐Induced Severe Cutaneous Adverse Reactions Is Phenotype‐Specific: HLA Class I Genotypes and Haplotypes

Co‐trimoxazole (CTX) causes various forms of severe cutaneous adverse reactions (SCARs). This case‐control study was conducted to investigate the involvement between genetic variants of human leukocyte antigen (HLA) and CYP2C9 in CTX‐induced SCARs, including Stevens‐Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS) in Thai patients. Thirty cases of CTX‐induced SCARs were enrolled and compared with 91 CTX‐tolerant controls and 150 people from the general Thai population. Cases comprised 18 SJS/TEN and 12 DRESS patients. This study demonstrated that genetic association of CTX‐induced SCARs was phenotype‐specific. HLA‐B*15:02 and HLA‐C*08:01 alleles were significantly associated with CTX‐induced SJS/TEN, whereas the HLA‐B*13:01 allele was significantly associated with CTX‐induced DRESS. In addition, a significant higher frequency of HLA‐A*11:01‐B*15:02 and HLA‐B*13:01‐C*03:04 haplotypes were detected in the group of CTX‐induced Stevens‐Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) and DRESS cases, respectively. Genetic association of CTX‐induced SCARs is phenotype‐specific. Interestingly, these association was observed only in HIV‐infected patients but not in non‐HIV‐infected patients

Management for improving patients’ knowledge and understanding about drug allergy

Background: Drug allergy a serious adverse drug reaction commonly concerned in healthcare practice. Inadequate documentation and communication between health providers, and limited health literacy and knowledge in patients could contribute to the re-occurrence of allergic reactions.Objective: To evaluate the effectiveness of initiatives aiming to improve patients’ knowledge, understanding and behavior in preventing recurrent drug allergy.Methods: A before-and-after study was conducted at an 800-bed university teaching hospital, involving patients with a history of drug allergy. Questionnaires, completed at baseline and one month after receiving information were used to compare knowledge and understanding of drug allergy and behaviors in relation to drug allergy cards. Patients in Group 1 received a brochure only, but patients in Group 2 also received a pharmacist counseling intervention in addition to the brochure. Outcomes were evaluated within intervention group and between intervention groups.Results: The study included 299 (30.4%) and 100 patients (100.0%) in Groups 1 and 2 respectively who completed the baseline questionnaire, of whom 179 (59.8%) and 96 (96.0%) completed the follow-up questionnaire. At baseline, higher educational levels and possession of a drug allergy card were significantly associated with better knowledge about drug allergy. After intervention, Group 2 had significantly greater increases in mean overall knowledge scores than Group 1 (p<0.01) and also greater increases in the proportions self-reporting carrying and presenting drug allergy cards (p<0.05 and p<0.01).Conclusions: Pharmacist counseling plus brochure may be more effective than brochure alone in promoting patients’ knowledge of drug allergy and drug allergy card importance

Comparison between the HLA-B∗58 : 01 Allele and Single-Nucleotide Polymorphisms in Chromosome 6 for Prediction of Allopurinol-Induced Severe Cutaneous Adverse Reactions

Severe cutaneous adverse drug reactions (SCARs) are life-threatening reactions. The strong association between the HLA-B∗58 : 01 allele and allopurinol-induced SCARs is well recognized. Screening for HLA-B∗58 : 01 allele before prescribing allopurinol in some populations has been recommended. Several single-nucleotide polymorphisms (SNPs) in chromosome 6 have been found to be tightly linked with the HLA allele, and these SNPs have been proposed as surrogate markers of the HLA-B∗58 : 01 allele. This study aimed to evaluate the association between three SNPs in chromosome 6 and allopurinol-induced SCARs in a Thai population. The linkage disequilibrium between the HLA-B∗58 : 01 allele and these SNPs was also evaluated. Results showed that three SNPs including rs9263726, rs2734583, and rs3099844 were significantly associated with allopurinol-induced SCARs but with a lower degree of association when compared with the HLA-B∗58 : 01 allele. The sensitivity, specificity, PPV, and NPV of these SNPs were comparable to those of the HLA-B∗58 : 01 allele. Although detection of the SNP is simpler and less expensive compared with that of the HLA-B∗58 : 01 allele, these SNPs were not perfectly linked with the HLA-B∗58 : 01 allele. Screening using these SNPs as surrogate markers of the HLA-B∗58 : 01 allele to avoid SCARs prior to allopurinol administration needs caution because of their imperfect linkage with the HLA-B∗58 : 01 allele