Why Is Imipenem/Cilastatin So Hard to Find? [Explained for 2026]

If you or a loved one has been prescribed Imipenem/Cilastatin — sold under the brand name Primaxin — and your pharmacy can't fill it, you're not alone. This powerful antibiotic has been listed as an active shortage on the FDA Drug Shortage Database, and it has been appearing on and off the ASHP (American Society of Health-System Pharmacists) shortage list for years. In this article, we'll explain exactly why this medication is so hard to find, what's driving the shortage, and what you can do about it.

What Is Imipenem/Cilastatin (Primaxin)?

Imipenem/Cilastatin is a combination carbapenem antibiotic — one of the most powerful classes of antibiotics available. Originally approved by the FDA in 1985 under the brand name Primaxin, it was the first carbapenem ever brought to market. It works by inhibiting bacterial cell wall synthesis, making it effective against a very wide range of bacteria, including many drug-resistant organisms that other antibiotics can't touch.

Unlike most antibiotics you might pick up at a retail pharmacy in pill form, Imipenem/Cilastatin is given intravenously (IV) or by intramuscular (IM) injection, almost always in a hospital, infusion center, or at home through an outpatient IV therapy (OPAT) program. Because of this, the shortage hits hospitalized patients and post-surgical patients especially hard.

Is Imipenem/Cilastatin Really in Shortage in 2026?

Yes. As of 2026, Imipenem and Cilastatin for Injection remains listed as "Currently in Shortage" on the FDA Drug Shortage Database. The shortage is not new — the drug has experienced supply disruptions multiple times over the past decade. The FDA and ASHP both track this shortage actively, which means the agency is working with manufacturers to mitigate supply disruptions.

The fact that it's on the FDA's official shortage list means this is not simply a local stocking issue at one pharmacy — it's a nationwide supply problem. Some presentations (vial sizes) may be more available than others at any given time, which is why it pays to check multiple sources.

Why Is There a Shortage of Imipenem/Cilastatin?

Several factors have contributed to the ongoing shortage:

• Manufacturing delays: Hospira (Pfizer) experienced manufacturing delays that reduced available supply. Sterile injectable antibiotics like Imipenem/Cilastatin are notoriously complex to manufacture, and even a small disruption in one facility can affect the entire national supply.

• Increased demand: Fresenius Kabi, another major manufacturer, cited increased demand as the reason for their shortage. Rising rates of antibiotic-resistant infections mean more patients need powerful antibiotics like carbapenems.

• Limited number of manufacturers: Only a handful of companies manufacture Imipenem/Cilastatin for the U.S. market. When one or two experience problems simultaneously, there is very little buffer in the supply chain.

• Complex sterile manufacturing requirements: As an injectable antibiotic, every batch must meet stringent sterility standards. Quality control holds or FDA inspections can shut down production lines, causing ripple effects across the entire supply.

• Post-pandemic supply chain fragility: The COVID-19 pandemic exposed and worsened vulnerabilities in the pharmaceutical supply chain, and sterile injectables have been among the hardest-hit categories ever since.

Who Is Most Affected by the Imipenem/Cilastatin Shortage?

Because Imipenem/Cilastatin is an IV antibiotic used almost exclusively in hospital settings or outpatient infusion programs, the shortage primarily impacts:

• Hospitalized patients with serious infections (pneumonia, sepsis, intra-abdominal infections)

• Patients with multi-drug resistant organisms (MDROs) where few other antibiotics work

• Immunocompromised patients (cancer patients, transplant recipients) receiving treatment for opportunistic infections

• Patients receiving outpatient IV antibiotic therapy (OPAT) at home or in infusion centers after discharge

What Can Patients and Families Do?

If you have been prescribed Imipenem/Cilastatin and are struggling to find it, here are concrete steps you can take:

1. Use medfinder to locate the drug: medfinder calls pharmacies and infusion centers near you to find which ones have Imipenem/Cilastatin in stock. This saves you hours of calling around yourself.

2. Ask your hospital pharmacy: Hospital pharmacies often have access to specialty distributors and group purchasing organizations (GPOs) that retail pharmacies don't. Ask if your hospital system can source the drug directly.

3. Ask about alternatives: Talk to your prescribing physician about whether another carbapenem like meropenem or ertapenem could work for your infection. See our full guide on alternatives to Imipenem/Cilastatin for details.

4. Check multiple pharmacies and infusion centers: Availability varies widely by location. A pharmacy two miles away may have it in stock while the one around the corner doesn't.

How medfinder Helps During Antibiotic Shortages

When an antibiotic as critical as Imipenem/Cilastatin is in shortage, every hour matters. medfinder is a paid service that does the legwork for you: you provide your medication, dosage, and location, and medfinder calls pharmacies and infusion centers to find which ones can fill your prescription. Results are sent directly to your phone via text message.

This is especially useful for a hospital-administered antibiotic like Imipenem/Cilastatin, where you may need to contact infusion pharmacies, specialty distributors, or hospital outpatient programs — not just your corner drugstore.

Will the Imipenem/Cilastatin Shortage Be Resolved?

The FDA and ASHP are actively working with manufacturers to address the shortage. However, sterile injectable antibiotics are among the most difficult drug shortages to resolve quickly due to the complexity of manufacturing, regulatory requirements, and long lead times. While alternative carbapenems are available (meropenem is widely used as a substitute), the shortage of Imipenem/Cilastatin itself is not expected to be fully resolved in the near term.

For the latest updates on the shortage, see our Imipenem/Cilastatin shortage update for patients in 2026.

Bottom Line

Imipenem/Cilastatin is hard to find in 2026 because of a combination of manufacturing challenges, limited producers, rising demand for carbapenems due to antibiotic-resistant infections, and ongoing sterile injectable supply chain fragility. If you need this medication, act proactively: use medfinder, consult your prescribing physician about alternatives, and contact your hospital pharmacy. Don't wait — for serious infections, finding the right antibiotic quickly can make all the difference.