FDA Enforces Post-Marketing Requirements under PREA

The FDA has issued non-compliance letters to Phathom Pharmaceuticals (NASDAQ: PHAT), Aucta Pharmaceuticals, and Cipher Pharmaceuticals (TSX: CPH) for failing to submit pediatric assessments within the timeframe required by the Pediatric Research Equity Act (PREA). The notification dates were June 11, 2026, for Voquezna, April 28 for Motpoly XR, and April 23 for Natroba, with responses submitted on June 25, June 11, and May 28, respectively. While this action does not involve product approval withdrawal, it is a regulatory measure for non-compliance with post-marketing requirements (PMR), and the listing on the FDA's public list exposes the companies' pediatric development and regulatory execution capabilities to the market. The FDA requires that within 45 days of notification, companies provide reasons for the delay and a proposed submission date or request for an extension.

Voquezna: Growth Potential and Regulatory Burden

Voquezna (vonoprazan) is a potassium-competitive acid blocker (P-CAB) that inhibits H+/K+-ATPase, the gastric proton pump in parietal cells. It is marketed for erosive and non-erosive gastroesophageal reflux disease (GERD) and Helicobacter pylori eradication therapy. The FDA approved it for eradication therapy in May 2022, for erosive esophagitis in November 2023, and for non-erosive GERD in July 2024, without convening a separate advisory committee (AdComm). Competitors include proton pump inhibitors (PPIs) such as omeprazole, esomeprazole, and dexlansoprazole. Phathom's net sales for 2025 were USD 175.1 million, and cumulative prescriptions exceeded 1.1 million as of February 2026. Given the company's long-term goal of achieving USD 1 billion in annual net sales, this action highlights the focus on the pediatric label expansion schedule and regulatory execution capabilities, rather than adult sales.

Motpoly XR and Natroba: Product-Specific Issues

Motpoly XR (lacosamide) is a once-daily extended-release antiepileptic drug that promotes the slow inactivation of voltage-gated sodium channels. It was approved by the FDA on May 4, 2023, for the treatment of partial-onset seizures and primary generalized tonic-clonic seizures in adults and children weighing 50 kg or more. The FDA notification stated that the pediatric assessment for PMR 4437-1, which was due on March 31, 2026, was not submitted, and the extension request of December 29, 2025, did not meet the requirements. Competing drugs include UCB (EBR: UCB)'s Vimpat (lacosamide) and generic lacosamide, with Vimpat's 2025 sales of EUR 128 million. Natroba (spinosad) is a topical suspension that overstimulates insect nicotinic acetylcholine receptors and is marketed for the treatment of head lice and scabies, competing with standard treatments such as permethrin and ivermectin.

Implications for Patient Access and Corporate Value

Natroba was first approved for the treatment of head lice in January 2011 and received approval for the treatment of scabies in children aged 4 years and older on April 28, 2021. However, the assessment or extension request for PMR 4062-1 was not submitted by March 31, 2026. Cipher reported product sales of USD 30.0 million for Natroba and authorized generic spinosad in 2025, indicating that managing the pediatric label is directly linked to commercial value. All three products are in the approved and marketed stages, so the key impact is on additional label expansion, insurance access, and regulatory compliance costs, rather than short-term prescription interruptions. In pediatric patients, weight-based pharmacokinetics and formulation suitability cannot be simply extrapolated from adult data, making adherence to the PMR schedule essential for safety and long-term product lifecycle management.