Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction of CYP2C9, HLA-A and HLA-B with anti-epileptic drugs

By developing evidence-based pharmacogenetics guidelines to optimize pharmacotherapy, the Dutch Pharmacogenetics Working Group (DPWG) aims to advance the implementation of pharmacogenetics (PGx). This guideline outlines the gene-drug interaction of CYP2C9 and HLA-B with phenytoin, HLA-A and HLA-B with carbamazepine and HLA-B with oxcarbazepine and lamotrigine. A systematic review was performed and pharmacotherapeutic recommendations were developed. For CYP2C9 intermediate and poor metabolisers, the DPWG recommends lowering the daily dose of phenytoin and adjust based on effect and serum concentration after 7-10 days. For HLA-B*15:02 carriers, the risk of severe cutaneous adverse events associated with phenytoin, carbamazepine, oxcarbazepine, and lamotrigine is strongly increased. For carbamazepine, this risk is also increased in HLA-B*15:11 and HLA-A*31:01 carriers. For HLA-B*15:02, HLA-B*15:11 and HLA-A*31:01 positive patients, the DPWG recommends choosing an alternative anti-epileptic drug. If not possible, it is recommended to advise the patient to report any rash while using carbamazepine, lamotrigine, oxcarbazepine or phenytoin immediately. Carbamazepine should not be used in an HLA-B*15:02 positive patient. DPWG considers CYP2C9 genotyping before the start of phenytoin "essential" for toxicity prevention. For patients with an ancestry in which the abovementioned HLA-alleles are prevalent, the DPWG considers HLA-B*15:02 genotyping before the start of carbamazepine, phenytoin, oxcarbazepine, and lamotrigine "beneficial", as well as genotyping for HLA-B*15:11 and HLA-A*31:01 before initiating carbamazepine.

Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction between CYP2D6, CYP3A4 and CYP1A2 and antipsychotics

The Dutch Pharmacogenetics Working Group (DPWG) aims to facilitate pharmacogenetics implementation in clinical practice by developing evidence-based guidelines to optimize pharmacotherapy. A guideline describing the gene-drug interaction between the genes CYP2D6, CYP3A4 and CYP1A2 and antipsychotics is presented here. The DPWG identified gene-drug interactions that require therapy adjustments when respective genotype is known for CYP2D6 with aripiprazole, brexpiprazole, haloperidol, pimozide, risperidone and zuclopenthixol, and for CYP3A4 with quetiapine. Evidence-based dose recommendations were obtained based on a systematic review of published literature. Reduction of the normal dose is recommended for aripiprazole, brexpiprazole, haloperidol, pimozide, risperidone and zuclopenthixol for CYP2D6-predicted PMs, and for pimozide and zuclopenthixol also for CYP2D6 IMs. For CYP2D6 UMs, a dose increase or an alternative drug is recommended for haloperidol and an alternative drug or titration of the dose for risperidone. In addition, in case of no or limited clinical effect, a dose increase is recommended for zuclopenthixol for CYP2D6 UMs. Even though evidence is limited, the DPWG recommends choosing an alternative drug to treat symptoms of depression or a dose reduction for other indications for quetiapine and CYP3A4 PMs. No therapy adjustments are recommended for the other CYP2D6 and CYP3A4 predicted phenotypes. In addition, no action is required for the gene-drug combinations CYP2D6 and clozapine, flupentixol, olanzapine or quetiapine and also not for CYP1A2 and clozapine or olanzapine. For identified gene-drug interactions requiring therapy adjustments, genotyping of CYP2D6 or CYP3A4 prior to treatment should not be considered for all patients, but on an individual patient basis only.

Dutch pharmacogenetics working group guideline for the gene-drug interaction of ABCG2, HLA-B and Allopurinol, and MTHFR, folic acid and methotrexate

The Dutch Pharmacogenetics Working Group (DPWG) aims to facilitate PGx implementation by developing evidence-based pharmacogenetics guidelines to optimize pharmacotherapy. This guideline describes the gene-drug interaction of ABCG2 with allopurinol, HLA-B with allopurinol, MTHFR with folic acid, and MTHFR with methotrexate, relevant for the treatment of gout, cancer, and rheumatoid arthritis. A systematic review was performed based on which pharmacotherapeutic recommendations were developed. Allopurinol is less effective in patients with the ABCG2 p.(Gln141Lys) variant. In HLA-B*58:01 carriers, the risk of severe cutaneous adverse events associated with allopurinol is strongly increased. The DPWG recommends using a higher allopurinol dose in patients with the ABCG2 p.(Gln141Lys) variant. For HLA-B*58:01 positive patients the DPWG recommends choosing an alternative (for instance febuxostat). The DPWG indicates that another option would be to precede treatment with allopurinol tolerance induction. Genotyping of ABCG2 in patients starting on allopurinol was judged to be 'potentially beneficial' for drug effectiveness, meaning genotyping can be considered on an individual patient basis. Genotyping for HLA-B*58:01 in patients starting on allopurinol was judged to be 'beneficial' for drug safety, meaning it is advised to consider genotyping the patient before (or directly after) drug therapy has been initiated. For MTHFR-folic acid there is evidence for a gene-drug interaction, but there is insufficient evidence for a clinical effect that makes therapy adjustment useful. Finally, for MTHFR-methotrexate there is insufficient evidence for a gene-drug interaction.

Dutch pharmacogenetics working group (DPWG) guideline for the gene-drug interaction of CYP2D6 and COMT with atomoxetine and methylphenidate

Pharmacogenetics (PGx) studies the effect of heritable genetic variation on drug response. Clinical adoption of PGx has remained limited, despite progress in the field. To promote implementation, the Dutch Pharmacogenetics Working Group (DPWG) develops evidence-based guidelines on how to optimize pharmacotherapy based on PGx test results. This guideline describes optimization of atomoxetine therapy based on genetic variation in the CYP2D6 gene. The CYP2D6 enzyme is involved in conversion of atomoxetine into the metabolite 4-hydroxyatomoxetine. With decreasing CYP2D6 enzyme activity, the exposure to atomoxetine and the risk of atomoxetine induced side effects increases. So, for patients with genetically absent CYP2D6 enzyme activity (CYP2D6 poor metabolisers), the DPWG recommends to start with the normal initial dose, bearing in mind that increasing this dose probably will not be required. In case of side effects and/or a late response, the DPWG recommends to reduce the dose and check for sustained effectiveness for both poor metabolisers and patients with genetically reduced CYP2D6 enzyme activity (CYP2D6 intermediate metabolisers). Extra vigilance for ineffectiveness is required in patients with genetically increased CYP2D6 enzyme activity (CYP2D6 ultra-rapid metabolisers). No interaction was found between the CYP2D6 and COMT genes and methylphenidate. In addition, no interaction was found between CYP2D6 and clonidine, confirming the suitability of clonidine as a possible alternative for atomoxetine in variant CYP2D6 metabolisers. The DPWG classifies CYP2D6 genotyping as being "potentially beneficial" for atomoxetine. CYP2D6 testing prior to treatment can be considered on an individual patient basis.

Dutch pharmacogenetics working group (DPWG) guideline for the gene-drug interaction between UGT1A1 and irinotecan

The Dutch Pharmacogenetics Working Group (DPWG) aims to facilitate PGx implementation by developing evidence-based pharmacogenetics guidelines to optimize pharmacotherapy. This guideline describes the starting dose optimization of the anti-cancer drug irinotecan to decrease the risk of severe toxicity, such as (febrile) neutropenia or diarrhoea. Uridine diphosphate glucuronosyl transferase 1A1 (UGT1A1 encoded by the UGT1A1 gene) enzyme deficiency increases risk of irinotecan-induced toxicity. Gene variants leading to UGT1A1 enzyme deficiency (e.g. UGT1A1*6, *28 and *37) can be used to optimize an individual's starting dose thereby preventing carriers from toxicity. Homozygous or compound heterozygous carriers of these allele variants are defined as UGT1A1 poor metabolisers (PM). DPWG recommends a 70% starting dose in PM patients and no dose reduction in IM patients who start treatment with irinotecan. Based on the DPWG clinical implication score, UGT1A1 genotyping is considered "essential", indicating that UGT1A1 testing must be performed prior to initiating irinotecan treatment.

Cardiovascular risk assessment methods yield unequal risk predictions: a large cross-sectional study in psychiatric secondary care outpatients

BACKGROUND

Patients with a mental illness are more likely to develop, and die from, cardiovascular diseases (CVD), necessitating optimal CVD-risk (CVR)-assessment to enable early detection and treatment. Whereas psychiatrists use the metabolic syndrome (MetS)-concept to estimate CVR, GPs use absolute risk-models. Additionally, two PRIMROSE-models have been specifically designed for patients with severe mental illness. We aimed to assess the agreement in risk-outcomes between these CVR-methods.

METHODS

To compare risk-outcomes across the various CVR-methods, we used somatic information of psychiatric outpatients from the PHAMOUS-, and MOPHAR-database, aged 40-70 years, free of past or current CVD and diabetes. We investigated: (1) the degree-of-agreement between categorical assessments (i.e. MetS-status vs. binary risk-categories); (2) non-parametric correlations between the number of MetS-criteria and absolute risks; and (3) strength-of-agreement between absolute risks.

RESULTS

Seven thousand twenty-nine measurements of 3509 PHAMOUS-patients, and 748 measurements of 748 MOPHAR-patients, were included. There was systematic disagreement between the categorical CVR-assessments (all p < 0.036). Only MetS-status versus binary Framingham-assessment had a fair strength-of-agreement (κ = 0.23-0.28). The number of MetS-criteria and Framingham-scores, as well as MetS-criteria and PRIMROSE lipid-scores, showed a moderate-strong correlation (τ = 0.25-0.34). Finally, only the continuous PRIMROSE desk and lipid-outcomes showed moderate strength-of-agreement (ρ = 0.91).

CONCLUSIONS

The varying methods for CVR-assessment yield unequal risk predictions, and, consequently, carry the risk of significant disparities regarding treatment initiation in psychiatric patients. Considering the significantly increased health-risks in psychiatric patients, CVR-models should be recalibrated to the psychiatric population from adolescence onwards, and uniformly implemented by health care providers.

TRIAL REGISTRATION

The MOPHAR research has been prospectively registered with the Netherlands Trial Register on 19th of November 2014 (NL4779).

Safe and informed prescribing of psychotropic medication during the COVID-19 pandemic

Treatment with psychotropic medication may sometimes be jeopardised because of the COVID-19 pandemic. One underlying reason is the lack of COVID-19-specific psychopharmacology guidelines. Here, we discuss five considerations arising from our clinical experience and pharmacological background knowledge to enable safe and well-informed psychopharmacotherapy during the COVID-19 pandemic.

Treatment of refractory SLE with rituximab plus cyclophosphamide: clinical effects, serological changes, and predictors of response

OBJECTIVE

To evaluate efficacy, serological responses, and predictors of response in patients with severe and refractory systemic lupus erythematosus (SLE) treated with rituximab plus cyclophosphamide.

METHODS

16 patients entered a treatment protocol using rituximab plus cyclophosphamide. Disease activity was assessed by the SLE disease activity index (SLEDAI) and by the British Isles Lupus Assessment Group (BILAG) index.

RESULTS

At six months follow up, mean SLEDAI values decreased significantly from (mean (SD)) 12.1 (2.2) to 4.7 (1.1). Clinical improvement (50% reduction in SLEDAI) occurred in all but three patients. All but one patient responded according to BILAG. Remission defined as SLEDAI <3 was achieved in nine of 16 patients. Isotype analysis of anti-dsDNA antibodies revealed preferential decreases of IgG and IgA, but not IgM. Higher absolute numbers of CD19+ cells at baseline were correlated with shorter depletion time (r = -0.6).

CONCLUSIONS

The majority of patients improved following rituximab plus cyclophosphamide. The differential downregulation of anti-DNA of the IgG and IgA but not the IgM isotypes supports the hypothesis that cells producing pathogenic autoantibodies are preferentially targeted by the treatment. The fact that greater absolute numbers of CD19+ cells at baseline predict a less impressive clinical and serological response suggests that more flexible dosing could be advantageous.

The potential interaction between oral anticoagulants and acetaminophen in everyday practice

OBJECTIVE

The drug-drug interaction between oral anticoagulants (especially warfarin) and acetaminophen has been described, but evidence is conflicting and evidence for a similar interaction between acenocoumarol or phenprocoumon and acetaminophen is limited. Therefore, a study was performed to determine the influence of acetaminophen on oral anticoagulation with acenocoumarol or phenprocoumon in everyday practice.

METHOD

Included were patients from two Dutch anticoagulant clinics who had used oral anticoagulants for at least three months and who started with acetaminophen (case group) or benzodiazepines (control group).

RESULTS

Fifty-four patients were included who had a first prescription of acetaminophen in their pharmacy record (during oral anticoagulant use) and twenty patients with a first prescription of a benzodiazepine (during oral anticoagulant use). The INR (International Normalized Ratio) difference before and after acetaminophen use was not statistically significant between the two groups and showed no dose dependency.

CONCLUSION

These data do not demonstrate that acetaminophen, in the dosages used in everyday practice, has a clinically relevant influence on the INR in patients using acenocoumarol or phenprocoumon.

Stabilization of oral anticoagulant therapy in hospitalized patients and characteristics associated with lack of stabilization

The initiation and stabilization of oral anticoagulant therapy in hospitalized patients in a setting without specialized medical or pharmaceutical advice, was studied. In addition, potential risk factors for lack of stabilization were studied. All patients from three wards (orthopaedic surgery, general surgery and internal medicine) in two Dutch hospitals, who were started on oral anticoagulant therapy and who gave informed consent, were included in this three months prospective follow-up study. When a patient had two consecutive INR's within the range 2-3 during hospitalization (on day 6 or later), he was defined as stable. Stable and unstable patients were compared with respect to age, gender, quetelet index, length of hospital stay, indication for oral anticoagulant therapy, induction dosing schedule of oral anticoagulant therapy, prescribing physician, type of hospital (teaching or non-teaching), concurrently used drugs, concurrently used drugs known to potentially interact with oral anticoagulant therapy (drug-drug interactions that influence INR) and (co)morbidity. A total of 125 patients, who all used acenocoumarol as oral anticoagulant, were recruited in the study. The study population mainly comprised orthopaedic discharges on prophylactic oral anticoagulants. The mean length of hospital stay was 14.5 days (median 11.0, standard deviation (SD) 10.2) for the patients included in the study (patients with a short length of stay < 6 days were excluded from the study, because of the definition of stability). 43 patients (34%) became stable during hospitalization. The second INR within the range was reached after on average 11.1 days (median 10.0, SD 4.5). 18 different induction dosing schedules were used. Differences in apparent risk of INR instability were statistically associated with length of hospital stay (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.78-0.92), concurrent use of musculoskeletal drugs, mainly NSAIDs, (OR 1.68, 95% CI 1.04-2.72) and two individual prescribing physicians (OR 6.61, 95% CI 1.47-29.82 for one physician and OR 0.23, 95% CI 0.06-0.99 for the other physician). This population has a high percentage of instability and reaches stability relatively late. The instability was associated with length of hospital stay, the concurrent use of musculoskeletal drugs (mostly NSAID's) and physician. Most of the unstable patients had INR's below therapeutic range, suggesting a conservative dosing habit. Part of the instability may also be due to the many different physicians who dose their own patients. Interventions to improve dosing may aid in better stabilization in hospitalized patients and thus in reduced length of hospital stay.