FDA approval · Drugs@FDA
ZOSYNpiperacillin sodium, tazobactam sodium
NDA050684 ·
FDA approved the original new drug application for ZOSYN on October 22, 1993, sponsored by WYETH PHARMS. FDA marks all 4 products under the application discontinued. FDA has approved 4 efficacy supplements on the application since, the most recent on May 26, 2020.
- Application
- NDA050684
- Sponsor
- WYETH PHARMS
- Original approval
- Review
- standard review
- Submission class
- Type 1 - New Molecular Entity and Type 4 - New Combination
- Active ingredient
- piperacillin sodium, tazobactam sodium
Browse every approval whose brand starts with Z, or the complete response letters FDA has published — the applications it did not approve.
Products under this application
| Ingredient and strength | Form | Route | Marketing status |
|---|---|---|---|
| piperacillin sodium EQ 36GM BASE/VIAL; tazobactam sodium EQ 4.5GM BASE/VIAL **Federal Register determination that product was not discontinued or withdrawn for safety or effectiveness reasons** | INJECTABLE | INJECTION | Discontinued |
| piperacillin sodium EQ 3GM BASE/VIAL; tazobactam sodium EQ 375MG BASE/VIAL **Federal Register determination that product was not discontinued or withdrawn for safety or effectiveness reasons** | INJECTABLE | INJECTION | Discontinued |
| piperacillin sodium EQ 4GM BASE/VIAL; tazobactam sodium EQ 500MG BASE/VIAL **Federal Register determination that product was not discontinued or withdrawn for safety or effectiveness reasons** | INJECTABLE | INJECTION | Discontinued |
| piperacillin sodium EQ 2GM BASE/VIAL; tazobactam sodium EQ 250MG BASE/VIAL **Federal Register determination that product was not discontinued or withdrawn for safety or effectiveness reasons** | INJECTABLE | INJECTION | Discontinued |
What “discontinued” means in FDA’s record
Drugs@FDA marks a product discontinued when it was never marketed, when it has been taken off the market, when it is made only for export, when it is made for military use, or when its approval was withdrawn for a reason other than safety or effectiveness. The record does not say which of those applies to a given product. The word on its own is not evidence that FDA found the drug unsafe.
Source: FDA, Drugs@FDA glossary of terms, under “Discontinued Drug Product”.
Approved efficacy supplements
An efficacy supplement is how a sponsor asks FDA to approve a change that needs clinical evidence — most often a new indication. FDA’s record gives each one a submission number, a date and a review priority. It does not say what any supplement approved, so neither does this page. The approval letter and label for each are on accessdata.fda.gov under the application number.
| Approved | Supplement | Review |
|---|---|---|
| S-1 | standard | |
| S-33 | standard | |
| S-46 | standard | |
| S-96 | standard |
FDA records other approved supplements on this application, by the class code it assigns them: Manufacturing (CMC) 30 · Labeling 28. Those are changes to the label or to how the drug is made rather than new clinical evidence, so they are counted here and not listed.
Source: FDA’s Drugs@FDA application file, via openFDA (export 2026-09-03). Every field on this page comes from that record.
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