How to Help Your Patients Find Imipenem/Cilastatin in Stock: A Provider's Guide

Helping a patient find an IV antibiotic during an active FDA shortage is one of the more frustrating discharge coordination challenges a provider faces. Imipenem/Cilastatin (Primaxin), a critical carbapenem antibiotic, has been on the FDA shortage list in 2026 — and when patients transition from inpatient to outpatient IV therapy (OPAT), finding a pharmacy with adequate stock before discharge can mean the difference between a seamless transition and a dangerous treatment gap. This guide gives you practical, actionable steps to help your patients succeed.

Step 1: Involve the Hospital Pharmacy Team Early

Don't wait until discharge day to begin sourcing OPAT antibiotics. Engage your hospital pharmacy team and discharge planners as soon as OPAT is identified as the likely discharge plan — ideally 48–72 hours in advance. Hospital pharmacists have direct lines to GPO contracts (Vizient, Premier, Intalere) and wholesaler allocations (McKesson, AmerisourceBergen, Cardinal Health) that can identify which manufacturers currently have available supply.

Key questions to ask your hospital pharmacist:

• "Which vial strengths of imipenem/cilastatin do you currently have in stock?"

• "Which manufacturer's product are we currently using — and are alternatives from other manufacturers available?"

• "Can the hospital dispense a bridge supply while the OPAT pharmacy sources the full course?"

• "Is meropenem or ertapenem a clinical equivalent for this patient's specific infection?"

Step 2: Work with Specialty Infusion Pharmacies

Specialty infusion pharmacies — such as Coram (CVS Specialty), BioScrip (now BrightSpring), Aveanna, and PharMerica — are the backbone of OPAT delivery. They are better equipped than retail pharmacies to source IV antibiotics during shortages because they have dedicated sterile injectable procurement channels and relationships with multiple wholesalers.

Before discharging the patient, confirm with the receiving infusion pharmacy:

• That they can confirm current availability — not just willingness to try to source it

• That they have enough supply for the full course of treatment, not just the first few days

• That they have a backup plan if their current supply runs out mid-course

Step 3: Use medfinder for Pharmacy Network Searches

medfinder for providers can help your team and your patients' caregivers locate infusion pharmacies and hospital outpatient pharmacies with Imipenem/Cilastatin currently in stock. medfinder calls pharmacies directly and reports back real-time availability — cutting down the hours your care team spends on hold with multiple pharmacies.

This is especially useful when you have multiple OPAT patients needing Imipenem/Cilastatin simultaneously, or when your usual infusion pharmacy partner cannot confirm supply.

Step 4: Consider Switching to an Equivalent Alternative Pre-Discharge

If Imipenem/Cilastatin cannot be reliably sourced for OPAT, switching to an equivalent agent before discharge — while the patient is still under your care and monitoring — is safer than mid-course switching in the outpatient setting. Clinical considerations for common alternatives:

• Meropenem: Best clinical equivalent for most indications. Preferred for CNS-related infections or patients with seizure history. May require q8h dosing (vs. ertapenem's once daily).

• Ertapenem: Once-daily dosing makes it ideal for OPAT when Pseudomonas aeruginosa has been excluded. Most convenient for patients managing home infusions.

• Piperacillin-Tazobactam: Broad-spectrum option for susceptible organisms when carbapenems are unavailable, but not appropriate for ESBL, CRE, or carbapenem-resistant infections.

Step 5: Communicate Clearly With the Patient and Caregivers

Patients and families need to understand the shortage and what to do if their OPAT pharmacy runs out of medication. Provide clear instructions:

• Do not skip or delay doses — call the office immediately if the pharmacy cannot fill the next supply

• Provide after-hours contact number for the OPAT team or covering provider

• Instruct them to check with their infusion pharmacy 48 hours before the next scheduled delivery to confirm supply is confirmed and ready

• Provide them with the medfinder contact information as a backup resource

Step 6: Document Shortage-Related Decisions

If you make a clinical decision to switch antibiotics because of the shortage (rather than purely clinical reasons), document this clearly in the chart. This protects you medicolegally and ensures continuity of care if another provider takes over. Note the shortage, the alternative selected, the clinical rationale for equivalence in this patient's case, and any monitoring parameters adjusted for the new agent.

Bottom Line for Providers

The Imipenem/Cilastatin shortage is a real and ongoing challenge for OPAT coordination. Start pharmacy coordination 48–72 hours before discharge, lean on your hospital pharmacy team for shortage intelligence, and use medfinder for providers to help locate pharmacies with current stock. Having a clear alternative antibiotic plan before the patient leaves the hospital is the single most important safeguard against dangerous treatment gaps.