Allopurinol hypersensitivity: investigating the cause and minimizing the risk

The Role of Oxidative Stress in Hyperuricemia and Xanthine Oxidoreductase (XOR) Inhibitors

Uric acid is the end product of purine metabolism in humans. Hyperuricemia is a metabolic disease caused by the increased formation or reduced excretion of serum uric acid (SUA). Alterations in SUA homeostasis have been linked to a number of diseases, and hyperuricemia is the major etiologic factor of gout and has been correlated with metabolic syndrome, cardiovascular disease, diabetes, hypertension, and renal disease. Oxidative stress is usually defined as an imbalance between free radicals and antioxidants in our body and is considered to be one of the main causes of cell damage and the development of disease. Studies have demonstrated that hyperuricemia is closely related to the generation of reactive oxygen species (ROS). In the human body, xanthine oxidoreductase (XOR) catalyzes the oxidative hydroxylation of hypoxanthine to xanthine to uric acid, with the accompanying production of ROS. Therefore, XOR is considered a drug target for the treatment of hyperuricemia and gout. In this review, we discuss the mechanisms of uric acid transport and the development of hyperuricemia, emphasizing the role of oxidative stress in the occurrence and development of hyperuricemia. We also summarize recent advances and new discoveries in XOR inhibitors.

Preparation and evaluation of functional allopurinol imprinted starch based biomaterials for transdermal drug delivery

This study focuses on the synthesis of functional allopurinol (ALP) imprinted biomaterials for a transdermal drug delivery using mung bean starch (MBS), polyvinyl alcohol (PVA), sodium benzoate (SB) as a crosslinking agent, and poloxamer (PX) as a thermo-sensitive polymer. Prepared functional biomaterials were characterized and evaluated by SEM, FT-IR analysis, and physical properties. Results of ALP recognition properties indicated that adsorbed amounts (Q) of ALP on functional ALP imprinted biomaterials were 3.8 to 4.9-fold higher than that of non-ALP imprinted biomaterial. Results of ALP release revealed that the ALP release rate for PX added biomaterials was 1.10 (36.5 °C) or 1.30 (45 °C) times faster than that at 25 °C. These results indicate that functional ALP imprinted biomaterials have thermo-sensitive properties due to the addition of PX. Results of ALP release using artificial skin indicated that ALP release was increased at a relatively steady-state rate for 3 h and that the ALP release behavior followed the non-Fickian diffusion mechanism.

Expression, localization and metabolic function of "resurrected" human urate oxidase in human hepatocytes

A high serum uric acid (SUA) concentration is associated with hyperuricemia (HUA) and gout. In order to obtain long-acting therapeutic effect, correction of purine metabolism at genetic level is advantageous. For this purpose, we expressed three "human-like" urate oxidases in human hepatocytes (HL-7702) by lentivirus-mediated transduction. Enzymatic assay revealed that the recombinant urate oxidases expressed in HL-7702 cells were functionally active. Electron microscopy study showed that the recombinant enzymes were localized to peroxisome and formed distinct crystalloid core structures as in other mammal cells. Although similar rate of uric acid degradation was observed for all recombinant urate oxidases, HL-7702-pLVX-UOX₈₃ cells and HL-7702-pLVX-UOX_214/217 cells retained more cell viability compared with HL-7702-pLVX-UOX_PBC at high uric acid level. This study provides a new direction for the treatment of gout and hyperuricemia.

Traditional Chinese medicine for gouty arthritis: A protocol for meta-analysis

BACKGROUND

Gouty arthritis (GA) is a chronic disease caused by monosodium urate crystal deposition. Repeated attacks of arthritis may lead to the deposition of urate to form gout stone, resulting in joint deformity and joint damage. Although GA is not fatal, it causes low work productivity and low quality of life. Western drug, such as febuxostat, colchicine, allopurinol, often cannot get satisfying curative effect, and may even lead to serious side effects, such as exfoliative dermatitis or uremia. However, the therapeutic effect of Traditional Chinese medicine is very satisfactory. The treatment effect of simiao powder, a Chinese patent medicine, combined with acupuncture was widely used on treatment of GA. Although it has been widely used in clinical practice, its relative effectiveness and safety have not been confirmed. Therefore, this study will use meta-analysis to verify the efficacy and safety of simiao powder combined with acupuncture in the treatment of GA.

METHODS

All randomized controlled trial of simiao powder combined with acupuncture for the treatment of RA from their inception 29 October, 2020 will be searched form the China National Knowledge Infrastructure, Wanfang Database, Chinese Science and Technology Periodical Database, Chinese Biomedical Literature Database, Pubmed, Embase, Web of Science, and the Cochrane library. Two authors will independently select studies, extract data based on pre-designed inclusion and exclusion criteria. Methodological quality assessment and risk of bias will be assessed using Cochrane bias risk tool. All data analysis will be conducted using Revman5.3, WinBUGS 1.4.3, and Stata14.2 software.

RESULTS

We will compare the different outcome indicators of various studies to provide a synthesis of the efficacy and safety of Simiao powder combined with acupuncture for GA patients. The main outcome measures included efficacy, remission rate (no drug symptoms), recurrence rate, clinical absolute score and relative score. Secondary outcome measures included related adverse reactions and uric acid concentration.

CONCLUSION

The findings of the study will provide helpful evidence for the efficacy and safety of simiao powder combined with acupuncture in the treatment of GA.

REGISTRATION NUMBER

This study protocol have been funded through a protocol registry. The registry number is INPLASY2020110028.

Exploring the potential of novel xanthine oxidase inhibitory peptide (ACECD) derived from Skipjack tuna hydrolysates using affinity-ultrafiltration coupled with HPLC-MALDI-TOF/TOF-MS

This study aimed to isolate and investigate the potential of the peptide alanine-cysteine-glutamic acid-cysteine-aspartic acid (ACECD), a novel xanthine oxidase inhibitory (XODI) peptide derived from Skipjack tuna hydrolysate (HS). Ultrafiltration membranes were used to obtain HS-based peptides as successive ultrafiltration fractions (of decreasing molecular weight) of UF-1, UF-2, UF-3, and UF-4. Their antioxidant and xanthine oxidase (XOD) inhibitory activities were determined and further characterized by affinity-ultrafiltration coupled with HPLC-MALDI-TOF/TOF-MS and in silico techniques. The results showed that peptides with a molecular weight (MW) cutoff of 600-1000 Da (UF-2) exhibited the highest antioxidant and XODI activities. A novel XODI peptide (ACECD) was identified with an IC₅₀ value of 13.40 mmol/L, which decreased by 21.24% and 51.40% compared to those of UF-2 and HS, respectively. Molecular docking indicated that ACECD inserted into the active center of Mo atoms in XOD, which led to competitive attachment with XOD and caused inhibition. The study findings indicated that the ACECD peptide could be useful as a safe XODI substance to alleviate hyperuricemia.

Efficacy and safety of urate-lowering therapy in people with kidney impairment: a GCAN-initiated literature review

OBJECTIVES

The aim was to evaluate the efficacy, defined as achieving target serum urate <6.0 mg/dl, and safety of urate-lowering therapies (ULTs) for people with gout and chronic kidney disease (CKD) stages 3-5.

METHODS

PubMed, The Cochrane Library and EMBASE were searched from 1 January 1959 to 31 January 2018 for studies that enrolled people with gout, who had an estimated glomerular filtration rate (eGFR) or creatinine clearance (CrCl) of <60 ml/min and exposure to allopurinol, febuxostat, probenecid, benzbromarone, lesinurad or pegloticase. All study designs other than case reports were included, except for people on dialysis, for whom we did include case reports.

RESULTS

There were 36 reports with an analysis of efficacy and/or safety based upon renal function: allopurinol (n = 12), febuxostat (n = 10), probenecid (n = 3), benzbromarone (n = 5), lesinurad (n = 5) and pegloticase (n = 1). There were 108 reports that involved people with gout and renal impairment but did not contain any analysis on efficacy and/or safety based upon renal function: allopurinol (n = 84), febuxostat (n = 14), benzbromarone (n = 1), lesinurad (n = 3) and pegloticase (n = 6). Most studies excluded people with more severe degrees of renal impairment (eGFR or CrCl of <30 ml/min). For allopurinol, in particular, there was significant variability in the dose of drug used and the efficacy in terms of urate lowering, across all levels of renal impairment.

CONCLUSION

There is a lack of evidence regarding the efficacy and/or safety of currently used ULTs according to different levels of renal function. Future studies should include patients with CKD and should report study outcomes stratified by renal function.

An update on gout diagnosis and management for the primary care provider

Gout is the most common inflammatory arthritis in the US, affecting 3.9% of the population. Although many effective gout therapies are available for acute flares and chronic management, it is suboptimally treated worldwide, and recurrent gout flares can cause significant pain and irreversible joint damage.

Risk factors for cutaneous reactions to allopurinol in Kinh Vietnamese: results from a case-control study

OBJECTIVE

The aim of this study was to investigate risk factors for cutaneous adverse reactions (CARs) in Kinh Vietnamese.

METHODS

All patients were prospectively recruited in Ho Chi Minh City. Presence of the HLA-B*58:01 allele was determined by real-time PCR-sequence-specific amplification by using the PG5801 Detection Kit (Pharmigene, Taipei). Patients with severe (SCARs) and mild (MCARs) CARs and controls were compared for differences in features prospectively collected, and odds ratios (ORs) with 95% confidence intervals (CIs) were estimated.

RESULTS

On comparing 32 patients with SCARs and 395 tolerant controls, we identified eight strong risk factors: increased age (OR 15.1 [95% CI 5.8-40.1], P < 0.0001), female sex (OR 333 [40-43,453], P < 0.0001), allopurinol for asymptomatic hyperuricemia (OR 955 [120-125,847], P < 0.0001), allopurinol starting dose > 150 mg (OR 316 [101-122], P < 0.0001), diuretics intake (OR 304 [35-40,018], P < 0.0001), eGFR < 60 ml/min/1.73 m² (OR 100 [32-353], P < 0.0001), history of allopurinol-induced skin reaction (OR 78 [6-10,808], P = 0.004), and HLA-B*58:01 carriage (OR 147 [45-746], P < 0.0001). HLA-B*58:01 allele frequency in controls was 7.3%. For MCARs (n = 74), risk factors were eGFR < 60 ml/min/1.73 m² (OR 4.9 [1.61-14.6], P = 0.006), history of allopurinol-induced skin reaction (OR 27 [2-3777], P = 0.01), and asymptomatic hyperuricemia (OR 27 [2-3777], P = 0.01).

CONCLUSION

This study confirmed 8 risk factors, including HLA-B*58:01, for SCARs and identified 3 risk factors for MCARs in Kinh Vietnamese. HLA-B*58:01 genotyping could guide the indication for allopurinol in Kinh Vietnamese patients with gout.

Comparison of efficacy and safety of urate-lowering therapies for hyperuricemic patients with gout: a meta-analysis of randomized, controlled trials

OBJECTIVES

To assess the efficacy and safety of the commonly used urate-lowering therapies (ULTs): febuxostat, allopurinol, and lesinurad in hyperuricemic patients with gout.

METHODS

We included all randomized controlled trials (RCTs) that compared ULTs with placebo or head to head. The primary efficacy endpoint was the proportion of subjects achieving the target serum urate (SU) level at month 6. Safety outcomes included total adverse events (AEs), serious AEs, withdrawals due to AEs, and AEs per organ system. A Bayesian network model was used to compare all ULTs with placebo and among themselves.

RESULTS

Fifteen RCTs were included for the analysis, in which 7968 patients were randomly assigned to take either placebo or one of 11 ULTs: allopurinol, febuxostat 40/80/120/240 mg/day, lesinurad 400 mg/day, lesinurad 200/400/600 mg/day plus allopurinol, and lesinurad 200/400 mg/day plus febuxostat. All ULTs were effective in achieving the target SU level at month 6 compared with placebo (ORs between 26.81 and 1928). Febuxostat 80/120/240 mg/day was superior to allopurinol and well tolerated for urate reduction. And as febuxostat dosage increased, more patients achieved the target SU level. Furthermore, the lesinurad combination with xanthine oxidase inhibitor (XOI) groups had a higher proportion of patients achieving the target SU level than the febuxostat 40 mg/day group (ORs between 2.89 and 9.17), the allopurinol group (ORs between 3.56 and 11.27), or the lesinurad 400 mg/day monotherapy group (ORs between 12.30 and 39.17) but might have a high risk of AEs.

CONCLUSIONS

All ULTs are effective in achieving the target SU level compared with placebo in hyperuricemic patients with gout. Lesinurad in combination with febuxostat or allopurinol is effective in urate lowering, especially for patients with inadequate response to XOI monotherapy. Key Points • All urate-lowering therapies (ULTs) were effective in achieving the target serum urate (SU) level at month 6 compared with placebo in hyperuricemic patients with gout. • Febuxostat 80/120/240 mg/day was superior to allopurinol and well tolerated for urate reduction. And as febuxostat dosage increased, more patients achieved the target SU level. • Lesinurad in combination with febuxostat or allopurinol was effective in urate lowering, especially for patients with inadequate response to xanthine oxidase inhibitor monotherapy, but might have a high risk of AEs.

Pharmacogenetic Testing for Prevention of Severe Cutaneous Adverse Drug Reactions

Severe cutaneous adverse reactions (SCAR), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug rash with eosinophilia and systemic symptoms (DRESS), are idiosyncratic and unpredictable drug-hypersensitivity reactions with a high-mortality rate ranging from 10% to over 30%, thus causing a major burden on the healthcare system. Recent pharmacogenomic studies have revealed strong associations between SCAR and the genes encoding human-leukocyte antigens (HLAs) or drug-metabolizing enzymes. Some of pharmacogenetic markers have been successfully applied in clinical practice to protect patients from SCAR, such as HLA-B*15:02 and HLA-A*31:01 for new users of carbamazepine, HLA-B*58:01 for allopurinol, and HLA-B*57:01 for abacavir. This article aims to update the current knowledge in the field of pharmacogenomics of drug hypersensitivities or SCAR, and its implementation in the clinical practice.

Heart disease and the risk of allopurinol-associated severe cutaneous adverse reactions: a general population-based cohort study

BACKGROUND

Allopurinol is commonly prescribed for gout, and its clinical use may expand with ongoing trials assessing its potential cardiorenal benefits. Because heart disease has been suggested to be a risk factor for allopurinol-associated severe cutaneous adverse reactions, we sought to confirm this association in a Canadian general population cohort.

METHODS

We used population data from British Columbia, Canada, to identify all incident allopurinol users between 1997 and 2015. We examined the association between heart disease (ischemic heart disease and heart failure) and the risk of hospital admission for severe cutaneous adverse reactions, adjusting for known and purported risk factors. We also evaluated the joint effects of combined clinical and demographic risk factors.

RESULTS

Among 130 325 allopurinol initiators, 109 hospital admissions occurred for allopurinol-associated severe cutaneous adverse reactions. The multivariable relative risk among those with heart disease was 1.55 (95% confidence interval 1.01-2.37). Patients with heart disease and chronic kidney disease who were started on an allopurinol dosage of greater than 100 mg/d had an 11-fold higher risk. Allopurinol initiation at a lower dosage among patients with heart disease and chronic kidney disease resulted in a fivefold reduction in risk. Older women with heart disease from regions with large Asian populations had a 23-fold higher risk of allopurinol-associated severe cutaneous adverse reactions than younger men without heart disease from other regions.

INTERPRETATION

Heart disease is independently associated with risk of allopurinol-associated severe cutaneous adverse reactions, similar to chronic kidney disease, and low-dosage allopurinol initiation may substantially mitigate this risk. Risk factors for these rare but serious reactions should be considered when initiating allopurinol.

Comparison of persistence rates between allopurinol and febuxostat as first-line urate-lowering therapy in patients with gout: an 8-year retrospective cohort study

INTRODUCTION/OBJECTIVES

Lifelong urate-lowering therapy (ULT) with xanthine oxidase inhibitors (XOIs), such as allopurinol and febuxostat, is the cornerstone of gout treatment. This study aimed to compare drug persistence between allopurinol and febuxostat as first-line ULT in patients with gout in real practice.

METHOD

In this retrospective cohort study, we evaluated 602 patients with gout in whom allopurinol or febuxostat was newly initiated from December 2011 to November 2018 at a tertiary rheumatology centre. Persistence was defined as the duration from the first description date to the end of treatment with XOIs or the end of the study period (November 2019).

RESULTS

Among the 602 gout patients, the mean age was 60.2 years and 234 (38.9%) patients had tophi. Allopurinol and febuxostat were started in 237 (39.3%) and 365 (60.6%) patients, respectively. During the study period, 282 (46.8%) patients stopped taking XOIs, and the most common reason for XOI withdrawal was poor health literacy (61.3%). The 1- and 5-year persistence rates of XOIs were 67.2% and 40.9%, respectively. In the Kaplan-Meier analysis, persistence rates of allopurinol were significantly lower than those of febuxostat (p < 0.001). In the multivariable Cox regression model, allopurinol use was a significant risk factor for discontinuation of XOIs (HR = 2.01, p < 0.001). In addition, the presence of tophi and symptom duration < 24 months was independently associated with a higher risk of XOI withdrawal.

CONCLUSIONS

Long-term persistence of XOIs was suboptimal, and allopurinol had worse persistence rates than febuxostat among patients with gout. Key Points • Long-term persistence of xanthine oxidase inhibitors (XOIs) as first-line urate-lowering therapy (ULT) among patients with gout was suboptimal, and the major reason for XOI discontinuation was poor health literacy in our study. • We demonstrated that allopurinol had worse persistence rates than febuxostat among patients with gout, suggesting that febuxostat is a better option for long-term ULT in light of medication adherence in a real-world setting. • Patients with gout with tophi and shorter symptom duration were found to be at high risk for poor persistence of XOIs.

HLA-B*58: 01 association in allopurinol-induced severe cutaneous adverse reactions: the implication of ethnicity and clinical phenotypes in multiethnic Malaysia

OBJECTIVE

The association between human leukocyte antigen (HLA)-B*58:01 and risk of allopurinol-induced severe cutaneous adverse reactions (AIS) was observed across different populations. We explore the association between HLA-B*58:01 and AIS risk in multiethnic Malaysian population. The HLA-B*58:01 risk for different AIS clinical phenotypes and ethnicity was determined.

METHODS

We performed a case-control association study by genotyping the HLA-B alleles of 55 patients with AIS [11 toxic epidermal necrolysis (TEN), 21 Steven Johnson syndrome (SJS) 22 drug reaction wit eosinophilia and systemic symptoms (DRESS) and one acute generalized exanthematous pustulosis (AGEP)] and 42 allopurinol-tolerant controls (ATC).

RESULTS

HLA-B*58:01 was positive in 89.1 and 14.3% of the AIS and ATC study groups [odds ratio (OR) = 49.0, 95% confidence interval (CI) = 14.6-164.4, P < 0.0001)], respectively. Our data showed that 93.8% of the AIS-SJS/TEN patients and 86.4% of the AIS-DRESS patients were HLA-B*58:01 positive (AIS-SJS/TEN, OR = 90, 95% CI = 16.9-470.1, P < 0.0001 and AIS-DRESS OR = 38, 95% CI = 8.5-169.2, P < 0.0001). Stratification by ethnicity and clinical phenotypes revealed a significant increased risk between HLA-B*58:01 and Chinese-AIS patients (OR = 137.5, 95% CI = 11.3-1680.2, P < 0.0001), in particular Chinese patients with AIS-SJS/TEN phenotype (100% HLA-B*58:01 positive). HLA-B*58:01 was positive in 90.9% Chinese AIS-DRESS (P < 0.0001). Highly significant associations of HLA-B*58:01 were observed in Malay AIS-SJS/TEN (OR = 78, 95% CI = 9.8-619.9, P < 0.0001) and Malay AIS-DRESS (OR = 54, 95% CI = 6.6-442.9, P < 0.0001). Although the number of Indian-AIS patients was relatively small (n = 2), both were HLA-B*58:01 positive.

CONCLUSION

Our data suggest strong associations between HLA-B*58:01 and AIS in Malaysian population with Chinese and Malays ethnicity. The strong association was also observed in three different clinical phenotypes of AIS, mainly the AIS-SJS/TEN.

2020 recommendations from the French Society of Rheumatology for the management of gout: Urate-lowering therapy

OBJECTIVE

To develop French Society of Rheumatology-endorsed recommendations for the management of urate-lowering therapy (ULT).

METHODS

Evidence-based recommendations were developed by 9 rheumatologists (academic or community-based), 3 general practitioners, 1 cardiologist, 1 nephrologist and 1 patient, using a systematic literature search, one physical meeting to draft recommendations and two Delphi rounds to finalize them.

RESULTS

A set of 3 overarching principles and 5 recommendations was elaborated. The overarching principles emphasize the importance of patient education, especially the need for explaining the objective of lowering serum urate (SU) level to obtain crystal dissolution, clinical symptoms disappearance and avoidance of complications. ULT is indicated as soon as the diagnosis of gout is established. SU level must be decreased below 300μmol/l (50mg/l) in all gout patients or at least below 360μmol/l (60ml/l) when the 300μmol/l target cannot be reached, and must be maintained at these targets and monitored life-long. The choice of the ULT primarily relies on renal function: in patients whose estimated glomerular filtration rate (eGFR) is above 60ml/min/1.73m², first-line ULT is allopurinol; in those with eGFR between 30 and 60ml/min/1.73m², allopurinol use must be cautious and febuxostat can be considered as an alternative; and in those whose eGFR is below 30ml/min/1.73m², allopurinol must be avoided and febuxostat should be preferred. Prophylaxis of ULT-induced gout flares involves progressive increase of ULT dosage and low-dose colchicine for at least 6 months. Cardiovascular risk factors and diseases, the metabolic syndrome and chronic kidney disease must be screened and managed.

CONCLUSION

These recommendations aim to provide simple and clear guidance for the management of ULT in France.

Studies on the structure-activity relationship and interaction mechanism of flavonoids and xanthine oxidase through enzyme kinetics, spectroscopy methods and molecular simulations

In this study, some flavonoids were screened as potent xanthine oxidase (XO) inhibitors in vitro. Flavonoid 9 was demonstrated to exhibit the inhibitory activity through a ping-pong mechanism. Further structure-activity relationship revealed that different structural elements had greatly influenced the inhibition effect on XO and underlined the requirement of hydroxyl groups at C5 and C4' of flavonoid type I. Moreover, some bioactive flavonoids could efficiently quench the intrinsic fluorescence of XO by either static or static-dynamic mixed mechanism. The synchronous fluorescence, ANS-binding fluorescence, Fourier transform infrared spectra and circular dichroism suggested that active flavonoids could bind to the active center of XO, prevent the entrance of substrate, and induce the rearrangement and conformation change of its secondary structures, ultimately resulting in the significant inhibition effect. Additionally, molecular docking further confirmed these conclusions and highlighted the great importance of hydrophobic interactions and hydrogen bonds for the formation of stable complex conformation.

Allopurinol hypersensitivity: Pathogenesis and prevention

Allopurinol, a first line urate-lowering therapy, has been associated with serious cutaneous reactions that have a high mortality. A number of risk factors for these serious adverse reactions have been identified including ethnicity, HLA-B∗5801 genotype, kidney impairment, allopurinol starting dose, and concomitant diuretic use. There is a complex interplay between these risk factors, which may (albeit rarely) lead to allopurinol-related serious adverse events. Although oxypurinol, the active metabolite of allopurinol, has been implicated, there is no defined drug concentration at which the reaction will occur. There is no specific treatment other than the cessation of allopurinol and supportive care. Whether hemodialysis, which rapidly removes oxypurinol, improves outcomes remains to be determined. Strategies to help reduce this risk are therefore important, which includes screening for HLA-B∗5801 in high-risk individuals, commencing allopurinol at low dose, and educating patients about the signs and symptoms of severe cutaneous adverse reactions, and what to do if they occur.

Spontaneous reports of hypersensitivity adverse drug reactions in Portugal: a retrospective analysis

BACKGROUND

Hypersensitivity adverse drug reactions (ADRs) are usually serious, unpredictable, and associated with high morbidity and mortality. This study describes cases of hypersensitivity ADRs spontaneously reported in Central Portugal.

METHODS

Spontaneous reports (SRs) of ADRs received between 2010 and 2017 were reviewed to identify cases of hypersensitivity reactions, using a Standardized MedDRA Query (SMQ). Seriousness, expectedness, and causality were assessed. Descriptive statistics were used to analyze data.

RESULTS

Among 2050 SRs, 598 (29.2%) contained 726 hypersensitivity ADRs: 657 (90.5%) serious, 569 (78.4%) unexpected, and 469 (64.6%) certainly related to drug exposure. Anaphylactic reactions (n = 93; 12.8%), rash maculopapular (n = 82; 11.3%), rash (n = 67; 9.2%) and DRESS (n = 54; 7.4%) were the most common reactions. Frequently implicated drug classes comprised antibiotics (n = 150; 23.0%), antineoplastic agents (n = 124; 19.0%), antigout preparations (n = 54; 8.3%), and anti-inflammatories (n = 44; 6.8%). Top-causative drugs were allopurinol (n = 54; 8.3%), docetaxel (n = 46; 7.1%), and trimethoprim/sulfamethoxazole (n = 26; 4.0%).

CONCLUSIONS

Most hypersensitivity ADRs were serious, unexpected, and with strong causal relationship with suspected drugs. Allopurinol was the top-causative drug. Besides antibiotics and anti-inflammatories, antineoplastic agents were frequently cited. These results deserve further investigation.

Hypersensitivity reactions with allopurinol and febuxostat: a study using the Medicare claims data

OBJECTIVE

To assess the risk of hypersensitivity reactions (HSRs) with allopurinol and febuxostat in a population-based study.

METHODS

We used the 5% Medicare beneficiary sample (≥65 years) from 2006 to 2012 to identify people with a newly filled prescription for allopurinol, febuxostat or colchicine. We used multivariable-adjusted Cox regression analyses to compare the hazard ratio (HR) of incident HSRs with allopurinol or febuxostat use versus colchicine use; separate analyses were done in people exposed to allopurinol. Propensity-matched analyses (5:1) compared hazards with allopurinol versus febuxostat.

RESULTS

Crude incidence rates of HSRs were as follows: allopurinol, 23.7; febuxostat, 30.7; and colchicine, 25.6 per 1000 person-years. Compared with colchicine, allopurinol, febuxostat and febuxostat+colchicine were associated with significantly higher HRs of HSRs, 1.32 (95% CI: 1.10 to 1.60) and 1.54 (95% CI: 1.12 to 2.12) and 2.17 (95% CI: 1.18 to 3.99), respectively. In propensity-matched analyses, febuxostat did not significantly differ from allopurinol; HR for HSRs was 1.25 (95% CI: 0.93 to 1.67). Compared with allopurinol start dose <200 mg/day, allopurinol start dose ≥300 mg/day, diabetes and female sex were associated with significantly higher hazard of HSRs, 1.27 (95% CI: 1.12 to 1.44), 1.21 (95% CI: 1.00 to 1.45) and 1.32 (95% CI: 1.17 to 1.48), respectively. The majority (69%) of HSRs occurred in the outpatient setting.

CONCLUSIONS

Compared with colchicine, allopurinol and febuxostat similarly increased the risk of HSRs. Allopurinol and febuxostat did not differ from each other. In allopurinol users, starting dose, female sex and diabetes increased this risk, findings that need further study.

Severe Cutaneous Adverse Drug Reactions Associated with Allopurinol: An Analysis of Spontaneous Reporting System in Southern Italy

Background

Allopurinol can induce severe cutaneous adverse reactions (SCARs), including Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome, Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).

Aims and Methods

We analyzed the Individual Case Safety Reports (ICSRs) sent from January 2001 until April 2019 to the Campania regional Center of Pharmacovigilance (Southern Italy) that reported allopurinol as suspected, with a focus on those reporting at least one serious cutaneous adverse drug reaction (ADR). This study was aimed to describe the main characteristics of all ADRs associated with allopurinol, analyze the proportion of serious cutaneous ADRs of total ICSRs related to allopurinol and to compare the main features (age, sex, seriousness and outcome) of ICSRs that reported serious cutaneous ADRs with those that did not.

Results

The Campania regional Center of Pharmacovigilance received 108 ICSRs that reported allopurinol as suspected. ADRs occurred more frequently in the elderly (median age: 71 years) and female patients (53.7%). Fifty-seven percent of all ADRs were classified as serious and 58% had a favorable outcome. Fifty-six ICSRs reported at least one serious cutaneous ADR; among these ICSRs, 37 cases of SCARs were found [DRESS syndrome (n = 3; 5.4%), SJS (n = 8; 14.3%) and TEN (n = 26; 46.4%)]. Serious cutaneous ADRs commonly occurred in the elderly (median age: 73 years) and female patients (62.5%). They frequently required hospitalization (75%) and had an unfavorable outcome (46%). No statistically significant differences were found between ICSRs that reported serious cutaneous ADRs and ICSRs that did not report serious cutaneous ADRs except for the seriousness degree “Hospitalization or its prolongation” and the outcome degrees “Unfavorable” and “Favorable”.

Conclusion

This study found that 52% (56/108) of all ICSRs having allopurinol as a suspected drug were serious cutaneous ADRs. Serious cutaneous ADRs associated with allopurinol frequently required hospitalization or prolonged hospitalization, and almost half had an unfavorable outcome.

Diagnostic Utility of Human Leukocyte Antigen B*15:02 Screening in Severe Carbamazepine Hypersensitivity Syndrome

Background

Despite many studies suggesting an association between human leukocyte antigen (HLA)-B*15:02 and carbamazepine (CBZ)-induced severe cutaneous adverse drug reactions essentially toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS), the evidence of association in different populations and the degree of association remain uncertain.

Materials and Methods

The primary analysis was based on population control studies. Data were pooled by means of a random-effects model, and sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-), diagnostic odds ratios (DOR), and areas under the summary receiver operating characteristic curve (AUC) were calculated.

Results

In 23 population control studies, HLA-B*15:02 was measured in 373 patients with CBZ-induced TEN/SJS and 3452 patients without CBZ-induced TEN/SJS. The pooled sensitivity, specificity, LR+, LR-, DOR, and AUC were 0.67 (95% confidence interval [CI] = 0.63-0.72), 0.98 (95% CI = 0.98-0.99), 19.73 (95% CI = 10.54-36.92), 0.34 (95% CI = 0.23-0.49), 71.38 (95% CI = 34.89-146.05), and 0.96 (95% CI = 0.92-0.98), respectively. Subgroup analyses for Han Chinese, Thai, and Malaysian populations yielded similar findings. Specifically, racial/ethnic subgroup analyses revealed similar findings with respect to DOR for Han Chinese (99.28; 95% CI = 22.20-443.88), Thai (61.01; 95% CI = 23.05-161.44), and Malaysian (30; 95% CI = 7.08-126.68) populations, which are similar to the pooled DOR for the relationship between the HLA-B*15:02 allele and CBZ-induced TEN/SJS across all populations (71.38; 95% CI = 34.89-146.05).

Conclusions

The present study reveals that CBZ is the leading cause of TEN/SJS in many countries. Screening of HLA-B*15:02 may help patients to prevent the occurrence of CBZ-induced TEN/SJS, especially in populations with a higher (≥5%) risk allele frequency.

Causative drugs for drug-induced cutaneous reactions in central China: a 608-case analysis

BACKGROUND

Reports regarding the causative drugs of drug-induced cutaneous adverse reactions in China are indistinct, such that different regions have reported the spectrum of drugs differs substantially in different clinical conditions.

OBJECTIVE

To explore the causative drugs that led to cutaneous reactions.

METHODS

Adverse drug reaction reports from central China were collected and divided into cutaneous adverse reactions and severe cutaneous adverse reactions groups. Cases were reviewed retrospectively for causative drugs.

RESULTS

The male:female ratio was equal in both cutaneous adverse reactions and severe cutaneous adverse reactions. In cutaneous adverse reactions (n=482), the highest incidence happened between 51 and 60 years of age and the top three causative drugs were antibiotics (48%), Chinese medicine (16%), and allopurinol (9%). In severe cutaneous adverse reactions (n=126), the highest incidence happened between 41 and 50 years of age and the top three causative drugs were sedative-hypnotics and antiepileptics (39%), antibiotics (22%), and allopurinol (15%). Carbamazepine was the most frequently used single-drug (16/18) in sedative-hypnotics and antiepileptics. β-lactams were the most frequently used antibiotics that induced both cutaneous adverse reactions and severe cutaneous adverse reactions.

STUDY LIMITATIONS

The small sample size, retrospective design, collection of cutaneous adverse reactions and severe cutaneous adverse reactions at different time frames and locations, and exclusion of patients taking more than five medications are limitations of the study.

CONCLUSIONS

Gender does not affect cutaneous adverse reactions and severe cutaneous adverse reactions. The top three drugs to induce cutaneous adverse reactions are antibiotics, Chinese medicine, and allopurinol, while those that triggered severe cutaneous adverse reactions are sedative-hypnotics and antiepileptics, antibiotics, and allopurinol. Carbamazepine is the most frequent single drug that induces severe cutaneous adverse reactions. β-lactams are the most frequently used antibiotics that induce both cutaneous adverse reactions and severe cutaneous adverse reactions.

Gout: state of the art after a decade of developments

This review article summarizes the relevant English literature on gout from 2010 through April 2017. It emphasizes that the current epidemiology of gout indicates a rising prevalence worldwide, not only in Western countries but also in Southeast Asia, in close relationship with the obesity and metabolic syndrome epidemics. New pathogenic mechanisms of chronic hyperuricaemia focus on the gut (microbiota, ABCG2 expression) after the kidney. Cardiovascular and renal comorbidities are the key points to consider in terms of management. New imaging tools are available, including US with key features and dual-energy CT rendering it able to reveal deposits of urate crystals. These deposits are now included in new diagnostic and classification criteria. Overall, half of the patients with gout are readily treated with allopurinol, the recommended xanthine oxidase inhibitor (XOI), with prophylaxis for flares with low-dose daily colchicine. The main management issues are related to patient adherence, because gout patients have the lowest rate of medication possession ratio at 1 year, but they also include clinical inertia by physicians, meaning XOI dosage is not titrated according to regular serum uric acid level measurements for targeting serum uric acid levels for uncomplicated (6.0 mg/dl) and complicated gout, or the British Society for Rheumatology recommended target (5.0 mg/dl). Difficult-to-treat gout encompasses polyarticular flares, and mostly patients with comorbidities, renal or heart failure, leading to contraindications or side effects of standard-of-care drugs (colchicine, NSAIDs, oral steroids) for flares; and tophaceous and/or destructive arthropathies, leading to switching between XOIs (febuxostat) or to combining XOI and uricosurics.

Gout

Gout is a chronic disease caused by monosodium urate (MSU) crystal deposition. Gout typically presents as an acute, self-limiting inflammatory monoarthritis that affects the joints of the lower limb. Elevated serum urate level (hyperuricaemia) is the major risk factor for MSU crystal deposition and development of gout. Although traditionally considered a disorder of purine metabolism, altered urate transport, both in the gut and the kidneys, has a key role in the pathogenesis of hyperuricaemia. Anti-inflammatory agents, such corticosteroids, NSAIDs and colchicine, are widely used for the treatment of gout flare; recognition of the importance of NLRP3 inflammasome activation and bioactive IL-1β release in initiation of the gout flare has led to the development of anti-IL-1β biological therapy for gout flares. Sustained reduction in serum urate levels using urate-lowering therapy is vital in the long-term management of gout, which aims to dissolve MSU crystals, suppress gout flares and resolve tophi. Allopurinol is the first-line urate-lowering therapy and should be started at a low dose, with gradual dose escalation. Low-dose anti-inflammatory therapies can reduce gout flares during initiation of urate-lowering therapy. Models of care, such as nurse-led strategies that focus on patient engagement and education, substantially improve clinical outcomes and now represent best practice for gout management.

Hepatic Bioactivation of Skin-Sensitizing Drugs to Immunogenic Reactive Metabolites

The clinical use of some drugs, such as carbamazepine, phenytoin, and allopurinol, is often associated with adverse cutaneous reactions. The bioactivation of drugs into immunologically reactive metabolites by the liver is postulated to be the first step in initiating a downstream cascade of pathological immune responses. Current mechanistic understanding and the ability to predict such adverse drug cutaneous responses have been partly limited by the lack of appropriate cutaneous drug bioactivation experimental models. Although in vitro human liver models have been extensively investigated for predicting hepatotoxicity and drug-drug interactions, their ability to model the generation of antigenic reactive drug metabolites that are capable of eliciting immunological reactions is not well understood. Here, we employed a human progenitor cell (HepaRG)-derived hepatocyte model and established highly sensitive liquid chromatography-mass spectrometry analytical assays to generate and quantify different reactive metabolite species of three paradigm skin sensitizers, namely, carbamazepine, phenytoin, and allopurinol. We found that the generation of reactive drug metabolites by the HepaRG-hepatocytes was sensitive to the medium composition. In addition, a functional assay based on the activation of U937 myeloid cells into the antigen-presenting cell (APC) phenotype was established to evaluate the immunogenicity potential of the reactive drug metabolites produced by HepaRG-derived hepatocytes. We showed that the reactive drug metabolites of known skin sensitizers could significantly upregulate IL8, IL1β, and CD86 expressions in U937 cells compared to the metabolites from a nonskin sensitizer (i.e., acetaminophen). Thus, the extent of APC activation by HepaRG-hepatocytes conditioned medium containing reactive drug metabolites can potentially be used to predict their skin sensitization potential.

ABCG2 gene polymorphism rs2231142 is associated with gout comorbidities but not allopurinol response in primary gout patients of a Chinese Han male population

Background

One common ATP-binding cassette subfamily G member 2 (ABCG2) gene variant, which is encoded by the single nucleotide polymorphism (SNP) rs2231142, was identified to take an essential part in gouty arthritis. However, the relationship between rs2231142, gout comorbidities and therapeutic effect of allopurinol in Chinese Han male population is still unclear. Wherefore, this study explored into the association between ABCG2 SNP rs2231142 affecting common comorbidities and the therapeutic effect of allopurinol in Chinese Han male gout patients.

Results

ABCG2 SNP rs2231142 and the gout comorbidities including nephrolithiasis and CKD were associated (P = 0.014 and P = 0.026). Group CKD stage = 1 were significantly different from those in group CKD stage≥2 regarding genotypes of ABCG2 gene polymorphism, while they were not significantly different from those in group CKD stage≥3. Meanwhile, the genotypes of rs2231142 and allopurinol response were not significantly associated (P = 0.588).

Conclusions

ABCG2 rs2231142 may predict the risk of kidney comorbidities for Chinese Han male gout patients, but not allopurinol response.

The Role of a “Treat-to-Target” Approach in the Long-Term Renal Outcomes of Patients with Gout

Background: Although gout is accompanied by the substantial burden of kidney disease, there are limited data to assess renal function as a therapeutic target. This study evaluated the importance of implementing a “treat-to-target” approach in relation to renal outcomes. Methods: Patients with gout who underwent continuous urate-lowering therapy (ULT) for at least 12 months were included. The effect of ULT on renal function was investigated by means of a sequential comparison of the estimated glomerular filtration rate (eGFR). Results: Improvement in renal function was only demonstrated in subjects in whom the serum urate target of <6 mg/dL was achieved (76.40 ± 18.81 mL/min/1.73 m2 vs. 80.30 ± 20.41 mL/min/1.73 m2, p < 0.001). A significant difference in the mean change in eGFR with respect to serum urate target achievement was shown in individuals with chronic kidney disease stage 3 (−0.35 ± 3.87 mL/min/1.73 m2 vs. 5.33 ± 11.64 mL/min/1.73 m2, p = 0.019). Multivariable analysis predicted that patients ≥65 years old had a decreased likelihood of improvement (OR 0.31, 95% CI 0.13–0.75, p = 0.009). Conclusions: The “treat-to-target” approach in the long-term management of gout is associated with better renal outcomes, with a greater impact on those with impaired renal function.

Effect of allopurinol in addition to hypothermia treatment in neonates for hypoxic-ischemic brain injury on neurocognitive outcome (ALBINO): study protocol of a blinded randomized placebo-controlled parallel group multicenter trial for superiority (phase III)

Background

Perinatal asphyxia and resulting hypoxic-ischemic encephalopathy is a major cause of death and long-term disability in term born neonates. Up to 20,000 infants each year are affected by HIE in Europe and even more in regions with lower level of perinatal care. The only established therapy to improve outcome in these infants is therapeutic hypothermia. Allopurinol is a xanthine oxidase inhibitor that reduces the production of oxygen radicals as superoxide, which contributes to secondary energy failure and apoptosis in neurons and glial cells after reperfusion of hypoxic brain tissue and may further improve outcome if administered in addition to therapeutic hypothermia.

Methods

This study on the effects of ALlopurinol in addition to hypothermia treatment for hypoxic-ischemic Brain Injury on Neurocognitive Outcome (ALBINO), is a European double-blinded randomized placebo-controlled parallel group multicenter trial (Phase III) to evaluate the effect of postnatal allopurinol administered in addition to standard of care (including therapeutic hypothermia if indicated) on the incidence of death and severe neurodevelopmental impairment at 24 months of age in newborns with perinatal hypoxic-ischemic insult and signs of potentially evolving encephalopathy. Allopurinol or placebo will be given in addition to therapeutic hypothermia (where indicated) to infants with a gestational age ≥ 36 weeks and a birth weight ≥ 2500 g, with severe perinatal asphyxia and potentially evolving encephalopathy. The primary endpoint of this study will be death or severe neurodevelopmental impairment versus survival without severe neurodevelopmental impairment at the age of two years. Effects on brain injury by magnetic resonance imaging and cerebral ultrasound, electric brain activity, concentrations of peroxidation products and S100B, will also be studied along with effects on heart function and pharmacokinetics of allopurinol after iv-infusion.

Discussion

This trial will provide data to assess the efficacy and safety of early postnatal allopurinol in term infants with evolving hypoxic-ischemic encephalopathy. If proven efficacious and safe, allopurinol could become part of a neuroprotective pharmacological treatment strategy in addition to therapeutic hypothermia in children with perinatal asphyxia.

Trial registration

NCT03162653, www.ClinicalTrials.gov, May 22, 2017.

Risk of cutaneous adverse reactions associated with allopurinol or febuxostat in real-world patients: A nationwide study

AIMS

Allopurinol carries a well-known risk of cutaneous adverse reactions (CARs). Although febuxostat, a xanthine-oxidase inhibitor with different chemical structure, has been considered an alternative to allopurinol, post-marketing case reports of life-threatening febuxostat-related CARs have been reported. We aimed to compare the risk of CARs between allopurinol and febuxostat in real-world settings and to assess the impact of the market entry of febuxostat on allopurinol use and associated CARs.

METHODS

A nationwide study was conducted using Taiwan's National Health Insurance Research Database. In the new-user cohort study, patients who received their first prescriptions of allopurinol or febuxostat were included, and Poisson regression was used to estimate the incidence rate ratios (IRRs) of CARs. In the interrupted time series analysis, time series data on new users and incidence rate of CARs were divided into three periods based on the reimbursement scheme of febuxostat in Taiwan, and segmented regression models were used to estimate changes in both the level and trend in each period.

RESULTS

We identified 526 cases of CARs with 487 among new users of allopurinol and 39 among new users of febuxostat (incidence rate: 15.37 vs 3.48 per 1000 person-years). Allopurinol was associated with higher risk of CARs (adjusted IRR 5.55, 95% CI [3.97-7.76]), mild CARs (1.86, [1.24-2.81]), severe CARs (16.75, [8.87-31.62]) and fatal CARs (16.18, [5.05-51.83]) than febuxostat. The overall incidence rates of xanthine-oxidase inhibitor-related CARs decreased from 15.28 to 14.28 per 1000 person-years after the initial reimbursement of febuxostat and further decreased to 9.46 after the reimbursement coverage of febuxostat expanded; however, the changes were not statistically significant.

CONCLUSION

Febuxostat can be considered an alternative for patients carrying risk factors for allopurinol-related CARs. However, since there were fatal cases of febuxostat-related CARs, the closely monitoring of symptoms of CARs during the initiation of febuxostat is still warranted.

Moving the Needle: Improving the Care of the Gout Patient

Gout is a the most common inflammatory arthritis in the United States. It is a significant cause of morbidity, disability, lost work days, and high healthcare utilization due to intermittent attacks, chronic inflammation, and joint damage. Despite our understanding of the prelude and pathophysiology of gout, hyperuricemia, it is still poorly misunderstood by patients and poorly managed by healthcare providers. Several parallel treatment paradigms have been developed by professional societies around the world based on the understanding of how hyperuricemia occurs, gout epidemiology, expert opinion, and clinical trials data in order to lower uric acid and eventually eliminate the patient's crystal burden. This review focuses on both the treatment of acute attacks, and more importantly, the long-term management of gout and the lowering of serum uric acid levels to a goal of < 6 mg/dl (0.360 mmol/l) or treating to target. Treating to a target serum uric acid goal is an opportunity to decrease morbidity and improve the quality of care of every gout patient.

The Presence of HLA-B75, DR13 Homozygosity, or DR14 Additionally Increases the Risk of Allopurinol-Induced Severe Cutaneous Adverse Reactions in HLA-B*58:01 Carriers

BACKGROUND

Although HLA-B*58:01 is a well-known risk factor for the development of allopurinol-induced severe cutaneous adverse reactions (SCARs), most of the HLA-B*58:01 carriers do not suffer from SCARs despite a long-term use of allopurinol. This suggests that there are other risk factors that determine the fate of HLA-B*58:01 carriers.

OBJECTIVE

The aim of this study was to investigate the additional genetic factors that increase the risk of allopurinol-induced SCARs in HLA-B*58:01 carriers.

METHODS

The incidence of allopurinol-induced SCARs was investigated according to coexisting HLA alleles in all subjects with HLA-B*58:01 who took allopurinol between 2003 and 2017. The allopurinol tolerant group was defined as a group who took allopurinol for more than 60 days without developing hypersensitivity and was compared with the allopurinol-induced SCAR group.

RESULTS

Among the retrospective cohort consisting of 367 HLA-B*58:01 carriers treated with allopurinol, 11 (3.0%) were diagnosed with allopurinol-induced SCARs. When HLA-B75, DR13 homozygosity, or DR14 was present, the incidence of SCARs increased up to 22.2% (odds ratio [OR], 19.568; P = .015), 20.0% (OR, 38.458; P = .001), and 10.7% (OR, 19.355; P = .004), respectively. Among the 153 HLA-B*58:01 carriers with chronic renal insufficiency (CRI), the incidence of SCARs doubled to 6.5% and further increased to 40%, 30%, and 37.5% in the presence of HLA-B75, DR13 homozygosity, or DR14, respectively.

CONCLUSIONS

Secondary screening with HLA-B75, DR13 homozygosity, and DR14 in addition to primary screening with HLA-B*58:01 would enable a more accurate prediction of SCAR occurrence, especially in patients with CRI.

Treatment Options for Gout

BACKGROUND

1-2% of adults in Germany suffer from gout. Gout is one of the few rheumatological diseases that can be cured. It arises through the deposition of uric acid crystals in joints as a result of hyperuricemia. Painful redness and swelling of the affected joints are typical findings. Multiple pertinent guidelines and treatment recommendations have been published, but there is reason to believe that patients with gout are not always treated accordingly.

METHODS

This review is based on relevant publications from the years 2000-2016 that were retrieved by a selective search in the Cochrane and PubMed databases.

RESULTS

In a person with normal renal function, asymptomatic hyperuricemia is not an indication for treatment to lower the serum uric acid level. The drugs of first choice for acute gouty arthritis are nonsteroidal antiinflammatory drugs (NSAID), corticosteroids, and colchicine. Treatment with xanthine oxidase inhibitors (XOI) or uricosuric drugs is indicated for patients with a recurrent or severe course; the target uric acid value is <6 mg/dL. Long-term treatment should be initiated only after resolution of the acute attack. For patients with refractory gout, lesinurad (approved in February 2016) in combination with XOI is a new treatment option that can be considered. Comprehensive patient education and counseling is an important component of the treatment of patients with gout. Regular laboratory follow-up is necessary as well.

CONCLUSION

The prevalence of gout is rising around the world. Patients with gout could benefit greatly from consistent implementation of the existing treatment guidelines and recommendations. In the future, controlled trials should be conducted to determine the best time to start treatment and the optimal target level for the serum uric acid concentration in terms of a risk/benefit analysis.

A liver-immune coculture array for predicting systemic drug-induced skin sensitization

Drug-induced skin sensitization is prevalent worldwide and can trigger life-threatening health conditions, such as Stevens Johnson Syndrome. However, existing in vitro skin models cannot adequately predict the skin sensitization effects of drugs administered into the systemic circulation because dermal inflammation and injury are preceded by conversion of parent drugs into antigenic reactive metabolites in the liver and subsequent activation of the immune system. Here, we demonstrate that recapitulation of these early tandem cellular processes in a compartmentalized liver-immune coculture array is sufficient to predict the skin sensitization potential of systemic drugs. Human progenitor cell (HepaRG)-derived hepatocyte spheroids and U937 myeloid cells, a representative antigen presenting cell (APC), can maintain their respective functions in 2 concentric micro-chambers, which are connected by a diffusion microchannel network. Paradigm drugs that are reported to cause severe cutaneous drug reactions (i.e. carbamazepine, phenytoin and allopurinol) can be metabolized into their reactive metabolites, which diffuse efficiently into the adjoining immune compartment within a 48 hour period. By measuring the extent of U937 activation as indicated by IL8, IL1β and CD86 upregulation upon drug administration, we show that the liver-immune coculture array more consistently and reliably distinguish all 3-paradigm skin sensitizing drugs from a non-skin sensitizer than conventional bulk Transwell coculture. Given its miniaturized format, design simplicity and prediction capability, this novel in vitro system can be readily scaled into a screenable platform to identify the skin sensitization potential of systemically-administered drugs.

Genetic Testing in Clinical Settings

Genetic testing is used for screening, diagnosis, and prognosis of diseases consistent with a genetic cause and to guide drug therapy to improve drug efficacy and avoid adverse effects (pharmacogenomics). This In Practice review aims to inform about DNA-related genetic test availability, interpretation, and recommended clinical actions based on results using evidence from clinical guidelines, when available. We discuss challenges that limit the widespread use of genetic information in the clinical care setting, including a small number of actionable genetic variants with strong evidence of clinical validity and utility, and the need for improving the health literacy of health care providers and the public, including for direct-to-consumer tests. Ethical, legal, and social issues and incidental findings also need to be addressed. Because our understanding of genetic factors associated with disease and drug response is rapidly increasing and new genetic tests are being developed that could be adopted by clinicians in the short term, we also provide extensive resources for information and education on genetic testing.

Association of non-immediate drug hypersensitivity with drug exposure: A case control analysis of spontaneous reports from a Tunisian pharmacovigilance database

PURPOSE

To assess delayed-type cutaneous reactions (DTCRs) related to drugs, using a case-control approach to qualify drug risks.

METHODS

The study used the Tunisian pharmacovigilance database of Monastir. The association between drugs and DTCRs was assessed using a case/non-case method. Drugs were grouped according to the ATC Classification System. Patients were defined as "cases" if they have developed DTCRs regardless of the causality assessment. All other reports were "non-cases". Association between reactions and drugs was calculated using the reporting odds ratio (ROR) with 95% confidence intervals (CIs). A p value < 0.05 was considered significant.

RESULTS

The analysis was carried out on 1798 reports, of which 867 concerned DTCRs (cases) and 931 concerned non-cases. The calculated risk estimates were significant for cefotaxime (ROR 2.1; 95% CI 1.5 to 3), pristinamycin (ROR 4; 95% CI 2 to 7.9), sulfamethoxazole (ROR 4.4; 95% CI 1.6 to 11.7), oxacillin (ROR 2.2; 95% CI 1.2 to 3.8), doxycycline (ROR 10.8; 95% CI 1.4 to 84.9), carbamazepine (ROR 3.3; 95% CI 1.7 to 6.2), phenobarbital (ROR 2.3; 95% CI 1.03 to 5.1), allopurinol (ROR 3.6; 95% CI 1.8 to 7.2), furosemide (ROR 2.4; 95% CI 1.3 to 6.3), hydrochlorothiazide(ROR 2.9; 95% CI 1.3 to 6.3) and candesartan (ROR 4.7; 95% CI 1.3 to 16.6).

CONCLUSION

Our findings corroborate risks for a number of drugs, such as antibacterials, antiepileptics and allopurinol in inducing DTCRs. Given the widespread use of these drug classes, awareness should be raised among patients and prescribers about these risks.

Predicting Response or Non-response to Urate-Lowering Therapy in Patients with Gout

PURPOSE OF REVIEW

To review the extent of treatment success or failure with the xanthine oxidoreductase inhibitors allopurinol and febuxostat and indicate how the dosage of urate-lowering therapy (ULT) may be modified to increase the response in the majority of patients with gout.

RECENT FINDINGS

Gout flares are associated with serum concentrations of urate above 0.42 mmol/L (7 mg/dL). Achieving and maintaining serum urate below 0.36 mmol/L is considered an effective response to ULT. On an intention to treat basis, clinical trials indicate that allopurinol at daily doses of 100 to 300 mg decreases serum urate adequately in only about 40% of gout patients while febuxostat 80 mg daily reduces serum urate adequately in approximately 70% of gout patients. Higher doses of ULT may be required in patients receiving concomitant diuretics. The addition of a uricosuric agent to allopurinol and febuxostat therapy significantly increases the proportion of patients achieving adequate lowering of serum urate. Finally, carriers of a genetic variant of the transporter, ABCG2 (BCRP), have a decreased response to allopurinol. Careful examination of medication adherence, titration of doses, and the addition of uricosuric agents increase the percentage of patients responding to allopurinol and febuxostat.

Physiology of Hyperuricemia and Urate-Lowering Treatments

Gout is the most common form of inflammatory arthritis and is a multifactorial disease typically characterized by hyperuricemia and monosodium urate crystal deposition predominantly in, but not limited to, the joints and the urinary tract. The prevalence of gout and hyperuricemia has increased in developed countries over the past two decades and research into the area has become progressively more active. We review the current field of knowledge with emphasis on active areas of hyperuricemia research including the underlying physiology, genetics and epidemiology, with a focus on studies which suggest association of hyperuricemia with common comorbidities including cardiovascular disease, renal insufficiency, metabolic syndrome and diabetes. Finally, we discuss current therapies and emerging drug discovery efforts aimed at delivering an optimized clinical treatment strategy.

Successful febuxostat desensitization in a patient with febuxostat hypersensitivity: A Malaysian experience

Over the years, allopurinol has been widely used as the preferred choice of urate lowering therapy in patients with gout. However, its role in patients with renal impairment is limited; and adverse reactions are well documented. Febuxostat, a newer oral non-purine xanthine oxidase inhibitor has been proven in several trials to be more effective and tolerable compared to allopurinol and may be used in patients with renal impairment. Here, we describe a case of successful febuxostat desensitization in a patient with a history of allopurinol- and febuxostat-induced adverse cutaneous reaction, as well as the protocol utilized.