Calcineurin Inhibitor Adverse Events in FAERS: 275,000 Reports and Key Safety Signals

Calcineurin inhibitors (CNIs)—anchored by tacrolimus, cyclosporine, and the newer agent voclosporin—are the cornerstone of immunosuppressiveness in solid organ transplantation and severe autoimmune diseases, such as lupus nephritis and rheumatoid arthritis. By binding to cytosolic immunophilins (tacrolimus to FKBP-12; cyclosporine to cyclophilin), CNIs inhibit the phosphatase activity of calcineurin. This blocks the dephosphorylation and nuclear translocation of the nuclear factor of activated T-cells (NFAT), preventing the transcription of interleukin-2 (IL-2) and subsequent T-cell activation. However, this potent mechanism carries a narrow therapeutic index, demanding therapeutic drug monitoring (TDM) to balance the prevention of graft rejection against severe systemic toxicities.

This article provides a class-level descriptive analysis of the calcineurin inhibitor safety profile within the FDA Adverse Event Reporting System (FAERS). Written for transplant clinical pharmacists, nephrologists, rheumatologists, and pharmacovigilance specialists, this review translates raw database counts into clinical context. All figures are computed from the public openFDA FAERS database extract. Spontaneous reporting systems like FAERS do not establish direct causality or provide exposure denominators. For broader methodology, see inside 20 million FAERS reports. For adjacent class cuts, see the anticoagulant FAERS analysis, azole antifungal adverse events (a major drug-interaction concern for CNIs), and the IgA nephropathy access landscape. For ophthalmic-specific cyclosporine access, see cyclosporine ophthalmic complex barriers.

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How many FAERS reports do the calcineurin inhibitors account for and how serious are they?

Across all reporting years in the public openFDA FAERS extract (comprising 20,328,575 total reports with an export date of June 8, 2026), the calcineurin inhibitors (any-role named) account for 274,568 deduplicated reports.

This volume places the CNI class among the most heavily reported specialty drug classes in our series. Given their primary use in preventing solid organ transplant rejection and managing severe glomerulonephritis, the outcome profile is expectedly severe. The table below provides a complete breakdown of the class-level outcomes:

The 77.6% serious case rate reflects the critical nature of the patient populations receiving these therapies. Solid organ transplant recipients and patients with active lupus nephritis face significant risks of acute graft rejection, severe opportunistic infections, and multi-organ complications.

The 14.6% fatal outcome rate must be interpreted within this clinical context. Solid organ transplant recipients are chronically immunocompromised and have high rates of cardiovascular disease, malignancies, and severe end-organ damage. Because FAERS captures any mention of a substance, the CNI is frequently co-reported in cases of death from sepsis, cardiovascular collapse, or disease progression, without the drug being the primary cause of mortality.

Per-Agent Report Distribution

The distribution of reports across individual calcineurin inhibitor molecules shows the dominance of tacrolimus:

1. Tacrolimus (combined): 136,177 reports for "tacrolimus" and 105,905 reports for "tacrolimus anhydrous" (Note: these represent overlapping substance-name strings within the same case; the deduplicated report-level total for tacrolimus is the leading volume in the class).
2. Cyclosporine: 110,156 reports
3. Voclosporin: 8,222 reports
4. Pimecrolimus: 1,277 reports

Tacrolimus is the preferred first-line CNI in the majority of liver, kidney, and heart transplant protocols globally, explaining its leading volume. Cyclosporine, while older, remains widely used in renal transplantation, graft-versus-host disease (GVHD) prophylaxis, and severe dry eye disease (restasis-class ophthalmic products). Voclosporin (Lupkynis) represents the newest addition to the class, approved in 2021 specifically for lupus nephritis.

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How large is the nephrotoxicity signal and does tacrolimus or cyclosporine score higher?

Nephrotoxicity is the defining, dose-limiting toxicity of the calcineurin inhibitor class. The mechanism is primarily driven by acute vasoconstriction of the afferent and efferent renal arterioles, mediated by altered release of vasoactive substances (such as endothelin and thromboxane) and a decrease in nitric oxide. Over time, chronic CNI exposure leads to irreversible structural damage, characterized by arteriolar hyalinosis, striped interstitial fibrosis, and tubular atrophy.

In our analysis, the combined nephrotoxicity signal (mapping acute kidney injury, renal impairment, and blood creatinine increased) accounted for 24,380 reports, about 8.9% of the entire CNI cohort. The largest individual renal Preferred Terms include:

Because this cohort is reported at the substance level (any role), we do not split these renal terms across tacrolimus, cyclosporine, and voclosporin here; the between-drug comparison comes from the published disproportionality literature.

Comparative Nephrotoxicity Analysis

• Disproportionality in the literature: 2025–2026 FAERS studies in Frontiers in Medicine and BMC Immunology both report high reporting odds ratios for CNI-associated kidney injury—tacrolimus around 4.8–5.2 and cyclosporine around 3.0–3.1—relative to the rest of the database. The Frontiers in Medicine analysis counted 57,436 tacrolimus, 44,451 cyclosporine, and 4,792 voclosporin deduplicated kidney-injury reports.
• Tacrolimus vs. Cyclosporine: Cyclosporine is historically associated with more pronounced acute afferent and efferent arteriolar vasoconstriction, while tacrolimus shows the higher absolute report volume in FAERS owing to its position as the first-line CNI in most modern transplant protocols. Both require close therapeutic drug monitoring (TDM) of trough levels to limit renal damage.
• Voclosporin's Renal Profile: Voclosporin is structurally modified from cyclosporine for roughly 3- to 4-fold greater potency, enabling lower, fixed dosing that does not require routine TDM. Its label still carries a nephrotoxicity warning, and blood-pressure and eGFR monitoring remain mandatory, particularly during the first weeks of therapy.

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Detailed Formulation Comparison: Bioavailability and Non-Interchangeability

To assist clinical transplant teams and pharmacy benefits managers, we have synthesized a clinical comparison matrix detailing the different formulations of tacrolimus and cyclosporine. This table highlights why different versions of the same chemical substance are NOT therapeutically interchangeable:

This formulation matrix demonstrates that minor differences in chemical structure or drug delivery systems have massive clinical implications. Inadvertent substitution between modified and non-modified cyclosporine, or between immediate-release and extended-release tacrolimus, can trigger acute graft rejection due to sub-therapeutic levels, or severe nephrotoxicity due to drug accumulation. Payers enforce strict prior-authorization and brand-necessary overrides to prevent these substitution errors at the retail pharmacy counter.

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Transplant Prior-Authorization Workflow and P&T Committee Guidelines

Because of the high cost of specialty immunosuppressants and the critical safety risks of CNI therapy, hospital P&T committees and commercial payers implement strict clinical workflows for drug approval. Below is the standard prior-authorization workflow utilized to manage calcineurin inhibitors in solid organ transplantation:

Patient Diagnosis (Renal/Liver Transplant) 
   ──> eGFR & HLA Typing Verification 
   ──> CNI Selection (Prograf/Envarsus/Neoral) 
   ──> Trough Level (TDM) Targets Set 
   ──> Prior Authorization Approval (12-Month Cycle)

Protocol Steps for P&T Immunosuppressive Approval

1. Diagnosis and Graft Verification: Prior authorization requests must include documentation of a solid organ transplant (e.g., kidney, liver, heart, lung) with the transplant date and facility code.
2. Formulation Specificity: The prescriber must specify the exact brand and formulation (e.g., Envarsus XR vs. Prograf). mg-to-mg conversions must be accompanied by the patient's recent stable trough levels.
3. Therapeutic Drug Monitoring (TDM) Requirement: Payers mandate that the prescribing transplant center perform routine blood trough monitoring. For renal transplants, the standard target trough ranges are:
   • Tacrolimus (Prograf): 5–15 ng/mL (typically higher in the first 3 months post-transplant, then maintained at 5–10 ng/mL).
   • Cyclosporine (Neoral): 100–300 ng/mL.
4. Renal Function Thresholds: For outpatients receiving CNIs, eGFR must be checked monthly. If eGFR drops by more than 30% from the patient's baseline post-transplant average, the workflow triggers a mandatory clinical pharmacy review to evaluate CNI-induced nephrotoxicity vs. acute rejection.
5. Re-Authorization Criteria: Re-authorization (typically every 12 months) requires proof of graft survival, absence of biopsy-proven acute rejection (BPAR), and compliance with routine TDM.

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Why is infection the #1 signal and what does the immunocompromised-population context mean?

Because calcineurin inhibitors suppress T-cell activation and IL-2 production, they impair cell-mediated immunity. This creates a chronic state of immunosuppression, leaving patients highly susceptible to opportunistic infections, viral reactivation, and bacterial pathogens.

In our analysis, the combined infection signal represents 27,438 reports, making it the #1 clinical safety signal in the CNI cohort (~10% of all reports). The signal spans the classic transplant infectious-disease spectrum: opportunistic viral reactivation (notably cytomegalovirus [CMV] and BK polyomavirus), bacterial lower-respiratory and urinary-tract infection, COVID-19, and sepsis. We do not tabulate individual infection-term counts here, because the any-role, substance-level cohort does not support reliable per-term attribution; the clinical pattern—not a single term's tally—is the point.

The Immunocompromised Population Context

The high volume of Cytomegalovirus (CMV) and BK virus reports highlights the unique clinical environment of CNI patients. In healthy individuals, these viruses are held in check by T-cell surveillance. In CNI-treated transplant recipients, T-cell suppression allows the viruses to replicate, leading to tissue-invasive CMV disease or BK virus-associated nephropathy (BKVAN).

To manage this risk, transplant centers implement routine viral load monitoring (PCR) and prophylaxis protocols using antiviral agents like valganciclovir. Payers manage this under the medical and pharmacy benefit, frequently bundling antiviral prophylaxis with CNI coverage.

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Critical Drug-Drug Interactions (DDIs) with Calcineurin Inhibitors

Both tacrolimus and cyclosporine are major substrates of the hepatic and intestinal cytochrome P450 3A4 (CYP3A4) enzyme and the efflux transporter P-glycoprotein (P-gp). Consequently, co-administration of CYP3A4/P-gp inhibitors or inducers can cause dramatic shifts in CNI blood concentrations, resulting in either acute toxicity or graft rejection.

The table below lists the most clinically significant drug-drug interactions that transplant clinicians and pharmacists must monitor:

This interaction profile highlights the high clinical risk associated with anti-infective therapy in transplant patients. For example, if a transplant recipient develops a systemic fungal infection and is prescribed voriconazole without a preemptive reduction in their tacrolimus dose, the patient is highly likely to experience rapid tacrolimus accumulation, leading to severe acute kidney injury (creatinine increased) and neurotoxicity.

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Where does voclosporin (Lupkynis, lupus nephritis) fit in the CNI safety profile?

Voclosporin (Lupkynis, BLA 761351) was approved by the FDA on January 22, 2021, for use in combination with background immunosuppressive therapy (typically mycophenolate mofetil and low-dose corticosteroids) for the treatment of adult patients with active lupus nephritis.

In our FAERS cohort, voclosporin accounts for 8,222 any-role reports, with lupus nephritis (8,472 indication mentions) confirming that the drug is being used in its FDA-approved target population. Because the cohort is substance-level and any-role, we do not split voclosporin's individual reaction-term counts here; its signal profile mirrors the CNI class—hypertension from systemic vasoconstriction, acute kidney injury requiring eGFR monitoring, increased infection risk from T-cell suppression, and the classic gingival and cosmetic effects seen across the class, generally less pronounced than with cyclosporine.

Clinical Positioning of Voclosporin

Voclosporin's safety profile is consistent with the CNI class, but its structural modification offers distinct advantages:

• No Routine TDM: By binding more tightly to calcineurin, voclosporin has a more predictable pharmacokinetic-pharmacodynamic relationship, eliminating the need for routine therapeutic drug monitoring. This reduces the laboratory monitoring burden for outpatients.
• Renal Profile: While voclosporin does not require TDM, it still causes acute renal vasoconstriction. PAYERS enforce strict prior-authorization rules, requiring baseline eGFR checks and mandating dose reductions or temporary holds if eGFR drops below 60 mL/min/1.73m² or decreases by more than 30% from baseline.

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Why are reporting volumes rising in 2024-2025 and what are the FAERS caveats?

An analysis of the reporting timeline shows that CNI reporting is rising, peaking in 2024 (25,476 reports) and 2025 (25,132 reports):

CNI Reporting Trend (Annual FAERS Volumes):
2019: 20,385  ──>  2020: 21,542  ──>  2023: 21,615  ──>  2024: 25,476  ──>  2025: 25,132

This rising trend is driven by several factors:

• Uptake of Voclosporin: The commercial expansion of voclosporin in lupus nephritis has added a new outpatient cohort to the CNI database.
• Specialty Drug Pharmacovigilance: Increased regulatory focus on postmarketing surveillance for transplant therapies has led to more systematic reporting by specialty pharmacy hubs and manufacturers.
• The Aging Transplant Population: Solid organ transplant recipients are living longer, resulting in accumulation of chronic CNI toxicities (such as chronic nephrotoxicity and skin malignancies) that are co-reported in FAERS.

Critical FAERS Caveats and Limitations

When evaluating this CNI safety data, healthcare professionals must keep several limitations in mind:

1. Substance-Level Reporting: FAERS is a substance-level database that does not automatically distinguish between routes of administration or formulations. Therefore, this cohort includes patients using topical pimecrolimus (1,277 reports for eczema) and ophthalmic cyclosporine (15,480 reports for dry eye, represented by Restasis and Cequa). The presence of "dry eye" and "eye irritation" (9,586 reports) in the top lists reflects these topical exposures, rather than systemic CNI toxicities.
2. Spontaneous Bias: FAERS relies on voluntary reporting by clinicians and consumers. Serious, acute events (like acute kidney injury or severe infection) are far more likely to be reported than mild or chronic side effects (like fine tremors or cosmetic gingival changes).
3. No Denominator: FAERS does not capture the total number of patients taking calcineurin inhibitors, preventing the calculation of actual incidence rates.

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FAQs

Does this FAERS analysis include topical pimecrolimus and ophthalmic cyclosporine (Restasis)?

Yes. Because FAERS is a substance-level database, these figures include any report containing the drug name, regardless of route of administration. Consequently, the cohort includes 1,277 reports for pimecrolimus (topical cream) and 15,480 reports for dry eye (reflecting ophthalmic cyclosporine use). This must be disclosed as a limitation when evaluating systemic toxicities.

Why is the death share 14.6% — are calcineurin inhibitors unusually lethal?

No. The 14.6% fatal outcome share reflects the severe, life-threatening comorbidities of the patients receiving these drugs (e.g., solid organ transplant recipients, severe lupus nephritis, and graft-versus-host disease), rather than direct drug toxicity. CNIs are high-alert medications, but deaths are primarily driven by underlying graft rejection, cardiovascular disease, and severe infections.

How does voclosporin's safety profile compare to tacrolimus and cyclosporine?

Voclosporin shares the CNI class safety profile, including risks of nephrotoxicity, hypertension, and infection. However, its structural modification increases its potency, eliminating the need for routine therapeutic drug monitoring (TDM). eGFR and blood pressure monitoring remain mandatory.

Are these reports suspect-level or any-mention, and what is the limitation?

These figures represent any-role-named reports (suspect, concomitant, or interacting). The primary limitations of FAERS are the lack of a patient exposure denominator (preventing incidence calculations), spontaneous reporting biases, and the inability to establish direct causality.

Which is reported more in FAERS, tacrolimus or cyclosporine?

Tacrolimus is reported more frequently, reflecting its position as the first-line calcineurin inhibitor in the majority of modern solid organ transplant protocols.

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Sources

1. U.S. Food and Drug Administration. FDA Adverse Event Reporting System (FAERS), via openFDA. Public extract (20,328,575 total reports, export dated June 8, 2026). openFDA FAERS Portal
2. Frontiers in Medicine (2026). Kidney adverse events associated with calcineurin inhibitors: a real-world pharmacovigilance study based on the FDA Adverse Event Reporting System and network pharmacology. Frontiers Article
3. Frontiers in Immunology (2026). Comparative neuropsychiatric safety signals of tacrolimus vs cyclosporine in transplant recipients: a real-world pharmacovigilance study based on the FDA Adverse Event Reporting System. Frontiers Article
4. BMC Immunology (2025). Comparative tacrolimus vs cyclosporine drug-induced kidney injury: a pharmacovigilance analysis of the FDA Adverse Event Reporting System. BMC Immunology Article
5. U.S. National Library of Medicine. DailyMed Prescribing Information: Tacrolimus Capsule/Injection, Cyclosporine Capsule, Voclosporin (Lupkynis) Capsule. DailyMed Database