Dapsone safety in hematology patients: Pathways to optimizing Pneumocystis jirovecii pneumonia prophylaxis in hematology malignancy and transplant recipients

A Comprehensive Review of Sulfonamide Hypersensitivity: Implications for Clinical Practice

Sulfonamides, which are drugs commonly prescribed in hospital and outpatient settings, have historically been associated with a high incidence of hypersensitivity reactions. It is believed that there is an increased risk of cross-reactions with other drugs that contain this functional group in their structure. However, it has not been conclusively established that the sulfonamide group is the sole cause of hypersensitivity reactions, as non-antibiotic sulfonamides do not share the same accessory groups with antibiotic sulfonamides. Therefore, cross-reactivity between different types of sulfonamides and sulfonamide-type antibiotics is not clearly demonstrated, and allergic reactions may involve other mechanisms. Misinformation about this topic can lead to inappropriate use of alternative antibiotics with lower efficacy or higher adverse effects, contributing to antibiotic resistance. It is crucial to individualize and monitor patients with a history of allergies to sulfonamide-type antibiotics when introducing a new drug containing sulfa and manage any adverse reactions promptly. Desensitization protocols may be a viable option for patients who specifically benefit from these antibiotics, particularly those who are immunosuppressed. This article provides a descriptive bibliographic review to update information on sulfa allergy, its prevalence, management, and recommendations to prevent such reactions and optimize pharmacotherapy, without underusing these drugs.

Mechanisms and management of drug-induced hyperkalemia in kidney transplant patients

Hyperkalemia is a common and potentially life-threatening complication following kidney transplantation that can be caused by a composite of factors such as medications, delayed graft function, and possibly potassium intake. Managing hyperkalemia after kidney transplantation is associated with increased morbidity and healthcare costs, and can be a cause of multiple hospital admissions and barriers to patient discharge. Medications used routinely after kidney transplantation are considered the most frequent culprit for post-transplant hyperkalemia in recipients with a well-functioning graft. These include calcineurin inhibitors (CNIs), pneumocystis pneumonia (PCP) prophylactic agents, and antihypertensives (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta blockers). CNIs can cause hyperkalemic renal tubular acidosis. When hyperkalemia develops following transplantation, the potential offending medication may be discontinued, switched to another agent, or dose-reduced. Belatacept and mTOR inhibitors offer an alternative to calcineurin inhibitors in the event of hyperkalemia, however should be prescribed in the appropriate patient. While trimethoprim/sulfamethoxazole (TMP/SMX) remains the gold standard for prevention of PCP, alternative agents (e.g. dapsone, atovaquone) have been studied and can be recommend in place of TMP/SMX. Antihypertensives that act on the Renin-Angiotensin-Aldosterone System are generally avoided early after transplant but may be indicated later in the transplant course for patients with comorbidities. In cases of mild to moderate hyperkalemia, medical management can be used to normalize serum potassium levels and allow the transplant team additional time to evaluate the function of the graft. In the immediate post-operative setting following kidney transplantation, a rapidly rising potassium refractory to medical therapy can be an indication for dialysis. Patiromer and sodium zirconium cyclosilicate (ZS-9) may play an important role in the management of chronic hyperkalemia in kidney transplant patients, although additional long-term studies are necessary to confirm these effects.

An evaluation of PJP prophylaxis and anemia among renal transplant recipients

BACKGROUND

Dapone and atovaquone are therapeutic options for PJP prophylaxis in renal transplant recipients. The objective of this study was to evaluate the incidence of anemia in renal transplant recipients receiving these agents.

METHODS

This is an IRB-approved, retrospective analysis of adult renal transplant recipients who received either dapsone or atovaquone. The primary endpoint was the change in hemoglobin within 90 days of drug initiation. Other endpoints of interest included incidence and management of anemia at multiple time points post-transplant. Categorical variables were compared with Pearson's chi-squared or Fischer's exact test and continuous data were compared utilizing Wilcoxon rank-sum test. Statistical analyses were performed using Stata 14.2.

RESULTS

A total of 478 patients were screened for inclusion; 50 patients were evaluated in both the dapsone and atovaquone groups. In the dapsone and atovaquone groups, the median age was 52 and 50.5 years, 44% and 42% were Caucasian, and median time to treatment initiation was 27 and 39 days post-transplant, respectively. All patients receiving dapsone had normal G6PD function. There was no difference in baseline hemoglobin between groups (9.7 g/dL vs 9.8 g/dL, P = .83). The median nadir hemoglobin values were 8.6 g/dL and 9.6 g/dL in the dapsone and atovaquone groups, respectively (P = .047). The median decrease in hemoglobin from baseline to nadir was 1.3 g/dL in dapsone patients and 0.2 g/dL in atovaquone patients (P = .001). Dapsone was discontinued in 46% of patients, whereas atovaquone was discontinued in 18% (P = .001).

CONCLUSION

Among renal transplant recipients with normal G6PD activity, dapsone is associated with greater hemoglobin reductions and rates of drug discontinuation as compared to atovaquone.

Sulfonamide desensitization in solid organ transplant recipients: A protocol-driven approach during the index transplant hospitalization

Trimethoprim-sulfamethoxazole (TMP-SMX) is the first-line agent for Pneumocystis jiroveci pneumonia (PJP) prophylaxis for solid organ transplant (SOT) recipients because of its efficacy for this indication, extended antimicrobial coverage, and favorable cost. Reported sulfonamide allergy is not uncommon and often results in TMP-SMX avoidance. Desensitization offers an efficacious and cost-effective alternative to TMP-SMX avoidance. Herein, we reviewed our experience with desensitization during the index transplant hospitalization among 52 SOT recipients with history of a non-anaphylactic sulfonamide allergy. Of those enrolled in the desensitization protocol, 92% (48/52) completed the protocol, with nearly 80% (41/52) still on TMP-SMX at 3 months without adverse reaction. Eleven patients discontinued TMP-SMX (7 for allergic reactions and 4 for non-allergic reasons) and switched to pentamidine. A cost savings of $575 per desensitization was calculated based on annual wholesale drug prices, for a total savings of $23 575. Additionally, the protocol did not delay discharge in any patient nor was it associated with any severe allergic reactions. These findings suggest TMP-SMX desensitization is safe and effective in SOT recipients with a history of non-anaphylactic, non-life-threatening sulfonamide hypersensitivity.

Beta-Lactam and Sulfonamide Allergy Testing Should Be a Standard of Care in Immunocompromised Hosts

Antibiotic allergies are reported in up to 1 in 4 immunocompromised hosts with significant impacts on antibiotic utilization and patient outcomes. Health services programs focused on de-labeling beta-lactam and sulfonamide allergy labels should be a standard of care in immunocompromised hosts.