Two medicines, side by side
Ampicillin vs gentamicin
Ampicillin and gentamicin are both labeled for bacterial infections. Drugs@FDA records approvals of ampicillin since 1966 and of gentamicin since 1970. Pharmacies paid $0.441 per ampicillin 500 mg capsule and $1.30 per mL (Gentamicin 80 mg/2 mL vial) (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, ampicillin is a penicillin-class antibacterial and gentamicin an aminoglycoside antibacterial.
Check it at the source: the ampicillin FDA label on DailyMed (effective February 21, 2025); the gentamicin FDA label on DailyMed (effective July 22, 2024).
Highlights of the ampicillin record
Ampicillin (Penbritin-S) · label of February 21, 2025
Used for
From the label: indicationsAmpicillin for injection is indicated in the treatment of infections caused by susceptible strains of the designated organisms in the following conditions: Respiratory Tract Infections caused by Streptococcus pneumoniae. Staphylococcus aureus (penicillinase and nonpenicillinase-producing), H. influenzae, and Group A beta-hemolytic streptococci. […]
On the market
- Earliest approval on file
- December 29, 1966
- Generic labelers
- 17 labelers
- Pharmacy cost
- $0.441 per capsule
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 3
Highlights of the gentamicin record
Gentamicin (Garamycin) · label of July 22, 2024
Used for
From the label: indicationsGentamicin sulfate ophthalmic solution is indicated in the topical treatment of ocular bacterial infections including conjunctivitis, keratitis, keratoconjunctivitis, corneal ulcers, blepharitis, blepharoconjunctivitis, acute meibomianitis, and dacryocystitis, caused by susceptible strains of the following microorganisms: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus pneumoniae, Enterobacter aerogenes, Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, Neisseria gonorrhoeae, Pseudomonas aeruginosa, and Serratia marcescens. […]
On the market
- Earliest approval on file
- June 19, 1970
- Generic labelers
- 24 labelers
- Pharmacy cost
- $1.30 per mL
Supply and safety
- Shortage
- No current entry
- Recalls
- 9
Source: FDA drug labels via openFDA (Ampicillin label of February 21, 2025, Gentamicin label of July 22, 2024); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do ampicillin and gentamicin differ on the record?
In FDA's classes, ampicillin is a penicillin-class antibacterial and gentamicin an aminoglycoside antibacterial.
Generics: ampicillin since 1971; gentamicin since 1966 (Drugs@FDA).
| Ampicillin | Gentamicin | |
|---|---|---|
| Labeled for | Bacterial infections, Urinary tract infections | Bacterial infections |
| Pharmacologic class | Penicillin-class Antibacterial | Aminoglycoside Antibacterial |
| How it works (label) | n/a | n/a |
| Half-life (label) | Due to maturational changes in renal function, ampicillin half-life decreases as postmenstrual age (a sum of gestational age and postnatal age) increases for infants with postnatal age of less than 28 days. | n/a |
| Earliest approval on file (Drugs@FDA) | December 29, 1966 | June 19, 1970 |
| First generic approved | March 3, 1971 | March 15, 1966 |
| Generic labelers (NDC) | 17 labelers | 24 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.441 per capsule (Ampicillin 500 mg capsule) | $1.30 per mL (Gentamicin 80 mg/2 mL vial) |
| 12-month price change | -8% | -21% |
| Boxed warning | No | No |
| Shortage now | A presentation being discontinued | No current entry |
| Recalls recorded | 3 | 9 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 8,240 | 15,709 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to ampicillin
- every medicine labeled for the same conditions