CYP2C19*2 status in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis

Pharmacogenetics in Primary Headache Disorders

Primary headache disorders, such as migraine, tension-type headache (TTH), and cluster headache, belong to the most common neurological disorders affecting a high percentage of people worldwide. Headache induces a high burden for the affected individuals on the personal level, with a strong impact on life quality, daily life management, and causes immense costs for the healthcare systems. Although a relatively broad spectrum of different pharmacological classes for the treatment of headache disorders are available, treatment effectiveness is often limited by high variances in therapy responses. Genetic variants can influence the individual treatment success by influencing pharmacokinetics or pharmacodynamics of the therapeutic as investigated in the research field of pharmacogenetics. This review summarizes the current knowledge on important primary headache disorders, including migraine, TTH, and cluster headache. We also summarize current acute and preventive treatment options for the three headache disorders based on drug classes and compounds taking important therapy guidelines into consideration. Importantly, the work summarizes and discusses the role of genetic polymorphisms regarding their impact on metabolism safety and the effect of therapeutics that are used to treat migraine, cluster headache, and TTH exploring drug classes such as nonsteroidal anti-inflammatory drugs, triptans, antidepressants, anticonvulsants, calcium channel blockers, drugs with effect on the renin-angiotensin system, and novel headache therapeutics such as ditans, anti-calcitonin-gene-related peptide antibodies, and gepants. Genetic variants in important phase I-, II-, and III-associated genes such as cytochrome P450 genes, UGT genes, and different transporter genes are scrutinized as well as variants in genes important for pharmacodynamics and several functions outside the pharmacokinetic and pharmacodynamic spectrum. Finally, the article evaluates the potential and limitations of pharmacogenetic approaches for individual therapy adjustments in headache disorders.

Toxic epidermal necrolysis syndrome induced by tigecycline: a case report

A 56-year-old man diagnosed with non-Hodgkin’s lymphoma underwent autologous bone marrow transplantation. He was subsequently admitted to the hospital with fever, and his symptoms were initially controlled by multiple antibiotics, including tigecycline. He then developed a generalized body rash that improved after treatment with anti-allergy drugs and steroids. Furthermore, tigecycline treatment for a second time resulted in a severe skin reaction with systemic symptoms, suggesting toxic epidermal necrolysis syndrome (TEN). The patient was shown to have the slow-metabolizing cytochrome P450 2C19 allele, denoted CYP2C19*2. He was transferred to a laminar flow ward and given strict mucosal care, together with corticosteroids and intravenous immunoglobulin. He recovered after 3 weeks of treatment. Tigecycline-induced Stevens–Johnson syndrome (SJS)/TEN has rarely been reported in the Chinese population. However, our experience suggests that Asians are more likely to have adverse reactions to drugs metabolized by the cytochrome P450 enzyme. Early identification of drug reactions and immediate cessation of the suspected drug is essential. Additionally, a combined therapy scheme and a clean laminar flow environment may improve the cure rate of SJS/TEN.

Pharmacogenetics of Carbamazepine and Valproate: Focus on Polymorphisms of Drug Metabolizing Enzymes and Transporters

Pharmacogenomics can identify polymorphisms in genes involved in drug pharmacokinetics and pharmacodynamics determining differences in efficacy and safety and causing inter-individual variability in drug response. Therefore, pharmacogenomics can help clinicians in optimizing therapy based on patient's genotype, also in psychiatric and neurological settings. However, pharmacogenetic screenings for psychotropic drugs are not routinely employed in diagnosis and monitoring of patients treated with mood stabilizers, such as carbamazepine and valproate, because their benefit in clinical practice is still controversial. In this review, we summarize the current knowledge on pharmacogenetic biomarkers of these anticonvulsant drugs.