The teratogenicity of allopurinol: A comprehensive review of animal and human studies

Multicentre study and systematic review: Allopurinol exposure during pregnancy

BACKGROUND

Data about the safety of allopurinol in pregnant women are sparsely reported.

AIMS

To investigate the risk of adverse pregnancy outcome and congenital abnormalities after in utero exposure to allopurinol in inflammatory bowel disease (IBD) pregnancies and in general.

METHODS

We collected safety data of patients with IBD who were treated with allopurinol during pregnancy between January 2013 and March 2022. Additionally, we performed a systematic review about the teratogenic potential of allopurinol.

RESULTS

We collected data from 42 allopurinol-exposed pregnancies, including one twin pregnancy; in all women, allopurinol was combined with a thiopurine. Six pregnancies (14.3%) resulted in miscarriage and one in stillbirth at 32 weeks. A congenital anomaly was observed in one newborn (coarctation of the aorta discovered postpartum). Three pregnancies, including the twin pregnancy, ended in moderate preterm delivery and one in very preterm delivery. Five neonates (15.2%) were small for gestational age. From our literature search, we identified an additional 102 allopurinol-exposed pregnancies resulting in 129 live births, including 36 infants from our cohort. Ten infants (7.8%) were born with a congenital anomaly. Two (1.6%) had a comparable pattern of multiple anomalies. The systematic review sub-analysis including only infants born to mothers with IBD (n = 76) revealed that 2.6% of infants had congenital anomalies after in utero exposure to a low dose of allopurinol.

CONCLUSIONS

Overall, the teratogenicity of allopurinol remains inconclusive. Children conceived by mothers treated for IBD with allopurinol/thiopurine co-therapy do not seem to have an increased risk of congenital anomalies.

Updates on the management of inflammatory bowel disease from periconception to pregnancy and lactation

Inflammatory bowel disease (IBD) affects reproductive planning due to psychological effects and mechanical problems related to surgery. Children of people with IBD have an increased risk of about 10% if one parent has IBD and up to 33% if both parents have IBD. The fertility of people with IBD is similar to the general population, but fertility might be reduced in individuals with active IBD, ileal pouch-anal anastomosis, or perianal Crohn's disease. Flaring disease during pregnancy increases complications, such as preterm birth. Thus, disease management with appropriate medications can optimise outcomes. As most medications have minimal fetal risks, people with IBD should be informed about the risks of stopping medications and the importance of maintaining remission. A period of disease remission is advisable before pregnancy and could reduce the risks for both the pregnant person and the fetus. Flexible endoscopy, intestinal ultrasound, and gadolinium-free magnetic resonance enterography are safe during pregnancy. We provide state-of-the-art knowledge on the basis of the latest evidence to ensure successful pregnancy outcomes in controlled IBD.

The presence of xanthine dehydrogenase is crucial for the maturation of the rat kidneys

The development of the kidney involves essential cellular processes, such as cell proliferation and differentiation, which are led by interactions between multiple signaling pathways. Xanthine dehydrogenase (XDH) catalyzes the reaction producing uric acid in the purine catabolism, which plays a multifaceted role in cellular metabolism. Our previous study revealed that the genetic ablation of the Xdh gene in rats leads to smaller kidneys, kidney damage, decline of renal functions, and failure to thrive. Rats, unlike humans, continue their kidney development postnatally. Therefore, we explored whether XDH plays a critical role in kidney development using SS-/- rats during postnatal development phase. XDH expression was significantly increased from postnatal day 5 to 15 in wild-type but not homozygote rat kidneys. The transcriptomic profile of renal tissue revealed several dysregulated pathways due to the lack of Xdh expression with the remodeling in inflammasome, purinergic signaling, and redox homeostasis. Further analysis suggested that lack of Xdh affects kidney development, likely via dysregulation of epidermal growth factor and its downstream STAT3 signaling. The present study showed that Xdh is essential for kidney maturation. Our data, alongside the previous research, suggests that loss of Xdh function leads to developmental issues, rendering them vulnerable to kidney diseases in adulthood.

Australian inflammatory bowel disease consensus statements for preconception, pregnancy and breast feeding

OBJECTIVE

Because pregnancy outcomes tend to be worse in women with inflammatory bowel disease (IBD) than in those without, we aimed to update consensus statements that guide the clinical management of pregnancy in patients with IBD.

DESIGN

A multidisciplinary working group was established to formulate these consensus statements. A modified RAND/UCLA appropriateness method was used, consisting of a literature review, online voting, discussion meeting and a second round of voting. The overall agreement among the delegates and appropriateness of the statement are reported.

RESULTS

Agreement was reached for 38/39 statements which provide guidance on management of pregnancy in patients with IBD. Most medications can and should be continued throughout pregnancy, except for methotrexate, allopurinol and new small molecules, such as tofacitinib. Due to limited data, no conclusion was reached on the use of tioguanine during pregnancy. Achieving and maintaining IBD remission before conception and throughout pregnancy is crucial to optimise maternofetal outcomes. This requires a multidisciplinary approach to engage patients, allay anxieties and maximise adherence tomedication. Intestinal ultrasound can be used for disease monitoring during pregnancy, and flexible sigmoidoscopy or MRI where clinically necessary.

CONCLUSION

These consensus statements provide up-to-date, comprehensive recommendations for the management of pregnancy in patients with IBD. This will enable a high standard of care for patients with IBD across all clinical settings.

Treating Preeclampsia in the COVID-19 Era: Is Allopurinol Useful as an Adjuvant Therapy? A Case Report and Review of the Literature

Acute respiratory syndrome-related coronavirus 2, or SARS-CoV-2, mainly affects the vulnerable population, especially those with comorbidities, such as pregnant women. SARS-CoV-2 has been found to cause multiple manifestations, one of which is preeclampsia. In preeclampsia, uric acid is excessively produced in the ischemic placenta and is released into circulation by placental reperfusion. Another effect of uric acid is oxidative stress with the production of oxygen free radicals associated with severe preeclampsia and fetal hypoxia. In our case report, we present the situation of a 38-year-old pregnant woman who developed preeclampsia after infection with SARS-CoV-2 with rapid evolution and an increased level of uric acid. We discuss the option of Allopurinol treatment in the third trimester of pregnancy instead of premature birth, with excellent benefits for both the mother and newborn. Additional clinical correlations between antioxidant treatment with Allopurinol and placental findings are needed.

Review of pregnancy in Crohn's disease and ulcerative colitis

Inflammatory bowel disease (IBD) frequently affects women of childbearing age and can have implications in pregnancy. Most women with IBD have comparable fertility with women in the general population. Fertility is reduced in women with active disease or previous ileal-pouch-anal anastomosis (IPAA) surgery and is temporarily reduced in men taking sulfasalazine. Women with IBD have an increased risk of preterm delivery, low birth weight, small-for-gestational-age infants and Cesarean section (CS) delivery, however, no increased risk of congenital abnormalities. These adverse outcomes are particularly prevalent for women with active IBD compared with those with quiescent disease. Conception should occur during disease remission to optimize maternal and fetal outcomes and reduce the risk of disease exacerbations during pregnancy. Pre-conception counseling is therefore pertinent to provide patient education, medication review for risk of teratogenicity and objective disease assessment. Most medications are safe during pregnancy and breastfeeding, with the exception of methotrexate, ciclosporin, allopurinol and tofacitinib. Delivery modality should be guided by obstetric factors in most cases; however, CS is recommended for women with active perianal disease and can be considered for women with inactive perianal disease or IPAA. In conclusion, most women with IBD have uncomplicated pregnancies. Active IBD is the predominant predictor of poor outcomes and disease exacerbations; therefore, maintenance of disease remission during and before pregnancy is crucial.

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.

Use of medications during pregnancy and breastfeeding for Crohn's disease and ulcerative colitis

Introduction: The peak age of diagnosis of inflammatory bowel disease (IBD) occurs during childbearing years, therefore management of IBD during pregnancy is a frequent occurrence. Maintenance of disease remission is crucial to optimize pregnancy outcomes, and potential maternal or fetal toxicity from medications must be balanced against the risks of untreated IBD.Areas covered: This review summarizes the literature on safety and use of medications for IBD during pregnancy and lactation.Expert opinion: 5-aminosalicylates, corticosteroids and thiopurines are safe for use during pregnancy, while methotrexate and tofacitinib should only be used with extreme caution. Anti-TNF agents (except certolizumab), vedolizumab, ustekinumab and tofacitinib readily traverse the placenta via active transport, therefore theoretically may affect fetal development. Certolizumab only undergoes passive transfer across the placenta, thus has markedly lower cord blood levels making it likely the safest biologic agent for infants. There is reasonable evidence to support the safety of anti-TNF monotherapy and combination therapy during pregnancy and lactation. Vedolizumab and ustekinumab are also thought to be safe in pregnancy and lactation, while tofacitinib is generally avoided due to teratogenic effects in animal studies.

Safety and tolerability of available urate-lowering drugs: a critical review

INTRODUCTION

Urate-lowering therapy (ULT) is the cornerstone of gout management, which is a widespread chronic illness characterized by hyperuricemia, arthropathy, tophus development, and urolithiasis. Since asymptomatic increased serum urate levels are associated with a higher risk of cardiovascular, renal and metabolic disorders, a larger use of ULTs in the general population is expected in the near future.

AREAS COVERED

This review will focus on the safety and tolerability profile of the available urate-lowering drugs: xanthine oxidase inhibitors (XOIs), uricosuric agents and injectable uricases.

EXPERT OPINION

Older drugs for ULT like allopurinol are well studied and extensively described from typical adverse effects (mild skin rash) to unusual fatal reactions, while febuxostat seems to be overall well tolerated. More evidence is required to define the safety profile of topiroxostat, arhalofenate, tranilast, and sulfinpyrazone. Furthermore, there are some unanswered questions about the pharmacological interactions of probenecid and the hepatotoxicity of benzbromarone. Despite a limited use in clinical practice, combination therapy with lesinurad or verinurad and XOI is not frequently accompanied by side effects. Rasburicase and pegloticase are usually well tolerated with some specific exceptions. Before prescribing UL drugs, physicians should take into account their safety profile tailoring the treatment on the patient characteristics.