How to Help Your Patients Find Zarontin in Stock: A Provider's Guide

As a neurologist or prescriber managing patients with absence epilepsy, you've likely fielded calls from patients who can't find Zarontin (ethosuximide) at their pharmacy. While no formal FDA shortage exists as of 2026, functional stocking problems are widespread—and patients are coming to you for solutions.

This guide gives you actionable steps to proactively reduce access barriers for your patients—from how you write the prescription to the tools you can share at discharge or during follow-up.

Step 1: Write Prescriptions to Maximize Dispensing Options

The single highest-impact prescribing change you can make is to allow formulation substitution. Add a note to prescriptions:

"May substitute ethosuximide oral solution (250 mg/5 mL) for capsules (250 mg) as needed for availability."

This simple addition allows the dispensing pharmacist to fulfill the prescription from whichever formulation is in stock. Bioavailability between formulations is generally comparable, though it is reasonable to check a drug level after a formulation switch in patients with borderline seizure control (therapeutic range: 40–100 μg/mL).

Step 2: Educate Patients to Plan Ahead

Proactive patient education at the time of prescription can prevent crisis calls later. Recommended talking points to include in your patient visit summary or discharge instructions:

• "Zarontin may not be on the shelf at every pharmacy. Start looking for a refill 1–2 weeks before you run out."
• "If your pharmacy doesn't have it, try an independent pharmacy or ask about the oral solution if you've been on capsules."
• "Never stop this medication suddenly. Call us if you can't find it and are running low."

Step 3: Direct Patients to medfinder

Share medfinder.com/providers with your patients. medfinder is a paid service that calls pharmacies on the patient's behalf to find which ones can fill their specific prescription. The patient enters their medication, dosage, and ZIP code—medfinder does the calling and delivers results by text message. This service is particularly valuable for:

• Elderly or mobility-limited patients who cannot call pharmacies themselves
• Patients in rural areas where pharmacy options are limited
• Pediatric patients where parents are managing the search alongside demanding schedules
• Patients who have already called several pharmacies without success

Step 4: Consider Mail-Order Pharmacy for Stable Patients

For patients who are stable and well-controlled on ethosuximide, transitioning to a 90-day supply via mail-order pharmacy can significantly reduce access challenges. Mail-order pharmacies maintain larger inventories of specialty medications and are less affected by regional stocking gaps. Ask patients to check with their insurance plan's preferred mail-order pharmacy (e.g., CVS Caremark, Express Scripts, or OptumRx) about ethosuximide availability.

Step 5: Know the Patient Assistance Landscape

If cost is a barrier (even when supply is available), direct patients to appropriate resources:

• Pfizer RxPathways (1-844-989-7284): For uninsured or government-insured patients meeting income eligibility (at or below 300% of Federal Poverty Level). May provide Zarontin at no cost.
• GoodRx: Generic ethosuximide as low as $33.61 per month for commercially insured and uninsured patients. Widely accepted at most retail pharmacies.
• SingleCare: Generic ethosuximide as low as $35.88 per month; comparable to GoodRx pricing.
• NeedyMeds and RxOutreach: Third-party assistance organizations that may have additional programs for low-income patients.

Step 6: Build a Protocol for Emergency Situations

Consider establishing a clear protocol in your practice for patients who call reporting they cannot find Zarontin and are running low. Key elements:

1. Triage urgency: How many days of medication remain?
2. If >5 days remain: Assist with pharmacy search (medfinder, call key pharmacies on your known list)
3. If <5 days remain: Consider bridge prescription for alternative (valproic acid or lamotrigine) while supply is sourced
4. Document the intervention in the patient's chart

Summary Checklist for Prescribers

• Add formulation substitution note to all ethosuximide prescriptions
• Educate patients to refill 1–2 weeks early and never stop abruptly
• Share medfinder.com and GoodRx with all new ethosuximide patients
• Consider mail-order for stable, long-term patients
• Have a documented protocol for patients who call running low on medication

For a broader clinical briefing on the ethosuximide availability situation, see our companion post: Zarontin Shortage: What Providers and Prescribers Need to Know in 2026.