FOIA Requests & Responses

FDA’s Internal Zorbium® Safety Reviews: What the Documents Reveal

Overview

Through a Freedom of Information Act (FOIA) request, we obtained 85 pages of internal FDA safety review documents for Zorbium® (buprenorphine transdermal solution). These documents, heavily redacted under trade secret exemptions, reveal a troubling pattern of escalating adverse events met with regulatory inaction.

Timeline Discrepancies

Critical Delay in Public Access:

• Latest review completed: March 28, 2024
• Documents received: September 24, 2025
• Data is 18 months old before reaching public view

This means veterinarians and cat owners have been making treatment decisions without access to FDA’s own safety concerns for a year and a half.

Key Findings

Escalating Adverse Event Reports

The documents show a dramatic increase in adverse event reports:

First Review Period (July 2022 – January 2023):

• 1,418 total reports
• 1,338 reports for cats
• 776 new cat reports in 6 months

Second Review Period (January 2022 – February 2024):

• 1,933 total reports
• 1,828 reports for cats
• 1,052 new cat reports since last review

Most Common Serious Clinical Signs:

• Behavioral disorder: 504 reports (26% frequency)
• Impaired consciousness
• Bradycardia (slow heart rate)
• Loss of consciousness
• Musculoskeletal disorders

Off-Label Animal Exposures

Despite being approved only for cats:

• 7 dog reports (product not approved for canines)
• 38 human exposure reports (including veterinary professionals)
• Documented human effects: eye irritation, dermal reactions

The “No Action Needed” Decision

Despite 1,052 new adverse event reports in cats, the FDA determined:

• ☒ No additional actions needed
• Recommendation: “Continue monitoring”
• Product moved to non-Tier 1 status (reduced oversight)

Critical Contradictions

1. Manufacturer’s Own Admission

Elanco stated in the documents:

“Equilibrium of distribution has not been achieved at this point in the lifecycle of this product. The estimated number of felines treated based on product distribution is likely overestimated.”

Translation: They cannot accurately calculate how many cats have received Zorbium®, making it impossible to determine the true adverse event rate. If fewer cats were treated than estimated, the actual adverse event rate would be higher.

2. Causality Dismissed Without Investigation

The FDA notes:

“Individual case review was conducted on Preferred Term Death and Preferred Term Impaired Consciousness regardless of causality. No verified associated signals or trends were identified.”

The Problem: Reviewing deaths “regardless of causality” while simultaneously finding “no verified signals” suggests they examined cases without conducting meaningful causality assessments.

3. Alert Report Surge

• 15-Day Alert Reports increased from 117 to 235 (doubling in 6 months)
• 15-Day Alerts are reserved for serious, unexpected adverse events requiring immediate FDA notification
• Zero 3-Day Alert Reports (reserved for most serious events)

4. The Benefit-Risk Conclusion

After every review showing increasing adverse events, documents conclude:

“Based upon current data available, Elanco US Inc. believes the benefit of the use of Zorbium® continues to outweigh the risk.”

Key Issue: This is Elanco’s determination, not an independent FDA assessment. The documents show FDA accepted the manufacturer’s risk-benefit analysis without presenting their own evaluation.

What’s Missing from These Documents

Our FOIA request specifically asked for:

• ✗ Documentation of the 266 feline deaths reported as of Q3 2024
• ✗ Causality determinations for deaths
• ✗ Comparative analyses with similar veterinary pain medications
• ✗ Threshold criteria for regulatory action
• ✗ Any records of internal FDA deliberations about regulatory actions
• ✗ Batch or lot-specific information linking adverse events to manufacturing

The FDA claims these records either don’t exist or are protected as trade secrets.

The Redaction Problem

Critical data remains hidden under Exemption (b)(4) – trade secrets/confidential commercial information:

• Actual number of tubes distributed
• Number of cats treated (exposure data)
• Specific adverse event counts in multiple sections
• Manufacturing and distribution details
• Personal identifying information under Exemption (b)(6)

Without exposure data, calculating adverse event rates is impossible. This makes meaningful safety evaluation by independent researchers or veterinarians nearly impossible.

Regulatory Red Flags

1. Downgraded Oversight During Crisis: Product moved to “non-Tier 1 status” precisely when adverse events were accelerating
2. Manufacturer Self-Assessment: FDA appears to rely on Elanco’s benefit-risk determination rather than conducting independent analysis
3. No Comparative Analysis: Documents contain no comparison of Zorbium®’s safety profile to other feline pain management options
4. “Early Lifecycle” Excuse: FDA accepted the rationale that high adverse event rates are expected because the product is new, rather than treating this as a safety signal

What This Means for Veterinarians and Cat Owners

The documents reveal that between January 2022 and February 2024:

• Nearly 2,000 adverse events were reported for a product approved only for post-surgical pain in cats
• The FDA had documented evidence of escalating serious adverse events
• No regulatory action was taken
• Veterinarians and pet owners had no access to this information for 18 months

The fundamental question remains: How many adverse events does it take before the FDA requires action from a manufacturer?

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These documents were obtained via FOIA request 2025-3031 and represent the FDA’s internal safety reviews through March 2024. Current adverse event totals may be significantly higher.

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Is Zorbium® Missing Batch-Level Safety Data?

The FDA says it has no records linking Zorbium® (buprenorphine transdermal solution) to specific manufacturing batches. Why aren’t these records available, and could Ivy Animal Health hold the missing data?

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The Missing Piece: Batch-Level Safety Tracking

When cat owners report deaths and injuries after Zorbium®, the first question should be: was it a bad batch?

That’s how drug safety usually works. Lots are tracked. Recalls happen when problems arise. But when we filed Freedom of Information Act (FOIA) requests with the FDA for Zorbium® batch data, the official response was surprising:

“The Center for Veterinary Medicine conducted a search and did not locate any records responsive to your request.”

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What the FDA Said

• No documentation links adverse events to specific Zorbium® batches or lots.
• No recalls, withdrawals, or corrections appear in the FDA’s files.
• No manufacturing deviations, GMP issues, or quality failures are documented in these records.

This leaves open an important question: how can safety be monitored without batch-level oversight?

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Ivy Animal Health: The Subsidiary Behind the Scenes

Elanco is the name on the label, but Ivy Animal Health is the subsidiary that produces Zorbium®.

This raises questions worth asking:

• Are Ivy’s manufacturing records stored separately from Elanco’s?
• Did the FDA’s FOIA search include Ivy’s records, or only Elanco’s?
• Could additional information exist under Ivy Animal Health’s files that hasn’t been searched yet?

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Why It Matters to Cat Owners

Without batch-level surveillance:

• A contaminated or mis-formulated lot could harm many cats without being traceable.
• Veterinarians may not be able to connect clusters of adverse events back to a single lot.
• Pet owners lose a vital layer of safety protection.

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Our Next Step

We are filing new FOIA requests aimed directly at Ivy Animal Health to better understand what records exist.

Asking these questions doesn’t accuse — it seeks transparency. And until answers come forward, one fact remains:

Zorbium® is being used on cats across the country without public batch-level safety data.

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August 26, 2025

This is an excerpt from the latest FOIA request

July 24, 2025

When Simple Questions Get Complicated Answers

“FDA: ‘You need to review individual cases for details’
Us: ‘OK, please review this case’
FDA: ‘You need to file a FOIA request’
Us: ‘For the case you said to review?’
FDA: ‘Who’s on first?'”

From Abbot & Costello’s Who’s on First? filmed in 1945 for the film “The Naughty Nineties”

Update on our FDA inquiry: Yesterday we asked a straightforward question about a mysterious adverse event report containing 266 cat deaths (AER ID: 2025-US-008923). After multiple exchanges, here’s what happened:

Our question: What does this single report with 266 deaths actually represent?

FDA’s first response: You need to review individual cases to get that level of detail.

Our follow-up: Please review this individual case and tell us what it contains.

FDA’s final response: You’ll need to file another FOIA request.

Let that sink in. When asked to explain what a single adverse event report represents, our federal drug safety agency’s solution is to make us file another formal information request that could take months to process.

This isn’t about complex data analysis or trade secrets. This is about a basic explanation of what happened in one case. The kind of information that should be readily available to anyone asking about drug safety.

The pattern is clear: When citizens ask direct questions about veterinary drug safety, they encounter layers of bureaucracy designed to exhaust persistence rather than provide transparency.

Subject: Veterinary Distribution of Zorbium®
Date: May 24, 2024
Source: New York State Department of Health

Subject: Safety Review Threshold Inquiry to FDA
Date: January 2, 2025
Source: FDA.HHS.Gov

©2025 Zorbium.com Research
FDA.HH.GOV
May be shared for educational/research purposes with attribution

Subject: Sales data for Zorbium, manufactured by Elanco, specifically, information on the total
number of Zorbium boxes sold since January 2022
Date: September 17, 2024
Source: US Dept. of Justice

©2025 Zorbium.com Research
Dept. of Justice
May be shared for educational/research purposes with attribution

© 2025 Zorbium.com Research FDA May be shared for educational/research purposes with attribution

Subject: Subject: FOIA Request – Safety Thresholds and Public Notification Criteria for Veterinary Drugs
Date: March 30, 2025
Source: FDA-CVM

© 2025 Zorbium.com Research FDA May be shared for educational/research purposes with attribution