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Gramicidin

Peptide

Gramicidin is a cyclic peptide antibiotic from Bacillus brevis, first isolated 1941, FDA-approved 1955 as Neosporin component. Topical use only (lozenges, eye drops, ointments) due to hemolysis. Gramicidin D (mixture of A/B/C) used clinically. Ophthalmic study (n=91): Effective and safe for bacterial corneal ulceration. Combined with polymyxin B and neomycin. One of first membrane-active peptide antibiotics. SAFETY CONCERN: Highly hemolytic - systemic use contraindicated.

Quick Answer

What it is

Gramicidin is a cyclic peptide antibiotic from Bacillus brevis, first isolated 1941, FDA-approved 1955 as Neosporin component. Topical use only (lozenges, eye drops, ointments) due to hemolysis.

Key findings

  • Grade A: Hemolytic Toxicity (Blood Health)
  • Grade B: Bacterial Corneal Ulceration (Eye Health)
  • Grade B: Bacterial Conjunctivitis (Eye Health)

Safety

No specific caution or interaction language was detected in the current summary/outcome notes.

⚠️ Research Notice

This peptide information is for educational and research purposes only. Peptides may not be FDA-approved for human use and may only be legally available for research purposes. Consult qualified healthcare professionals before considering any peptide compounds.

ℹ️ Quick Facts: Gramicidin

Quick Facts: Gramicidin

  • Best Evidence:Grade A
  • Conditions Studied:4
  • Research Outcomes:8
  • Grade A Findings:1
  • Grade B Findings:3
  • Key Effect:Blood Health
A1
B3
C4
D0
4 conditions · 8 outcomes

Detailed Outcomes

|
A
Hemolytic Toxicity
SAFETY CONCERN: Highly hemolytic - cannot be administered systemically. Internal use contraindicated. Topical absorption negligible. Limits use to topical applications only.
large↑Worsens
B
Bacterial Corneal Ulceration
Retrospective study (n=91): Polymyxin B/neomycin/gramicidin effective and safe for bacterial corneal ulcers. 51% culture-positive with S. aureus and P. aeruginosa most common. Standard treatment at major medical centers.
moderate↑Improves
B
Bacterial Conjunctivitis
FDA-approved ophthalmic formulation (Neosporin Ophthalmic). Triple antibiotic combination for bacterial eye infections. Standard first-line therapy for superficial ocular infections.
moderate↑Improves
B
Wound Infections
Component of Neosporin ointment for wound infection prevention. Combined with neomycin and polymyxin B. Widely used OTC for minor cuts, scrapes, and burns.
moderate↑Improves
C
Antimicrobial Activity
18 preclinical studies support this finding. Primarily preclinical evidence.
moderate↑Improves
C
Lipid Profile
6 preclinical studies support this finding. Primarily preclinical evidence.
small↓Improves
C
Safety/Tolerability
4 preclinical studies support this finding. Primarily preclinical evidence.
small↑Improves
C
Sore Throat Symptoms
Systematic review: Limited evidence for topical antibiotics in sore throat. Gramicidin lozenges used historically. Double-blind study (n=468): Gramicidin/cetylpyridinium combination tested. Evidence quality remains low.
small↑Worsens

Research Citations (27)

Lipid Composition of Nanocarriers Shapes Interactions of Cyclic Antimicrobial Peptide Gramicidin S with Their Membranes.
(2025)
PMID: 40725193
Discovery of a potent ornithine-modified gramicidin S analogue against drug-resistant Staphylococcus aureus and Enterococcus faecalis with minimal red blood cell toxicity.
(2025)
PMID: 40288118
Machine-Learning Approach to Increase the Potency and Overcome the Hemolytic Toxicity of Gramicidin S.
(2025)
PMID: 40694383
Modifying Membranotropic Action of Antimicrobial Peptide Gramicidin S by Star-like Polyacrylamide and Lipid Composition of Nanocontainers.
(2024)
PMID: 39201384
A New Gramicidin S Analogue with Potent Antibacterial Activity and Negligible Hemolytic Toxicity.
(2024)
PMID: 38900970
Efficacy of topical drugs in the treatment of patients with acute inflammatory diseases of the pharynx
(2020)
PMID: 32027334
Topical (local) antibiotics for respiratory infections with sore throat: An antibiotic stewardship perspective
(2019)
PMID: 31407824
The Multifaceted Antibacterial Mechanisms of the Pioneering Peptide Antibiotics Tyrocidine and Gramicidin S
(2018)
PMID: 30301848
Gramicidin Lateral Distribution in Phospholipid Membranes: Fluorescence Phasor Plots and Statistical Mechanical Model.
(2018)
PMID: 30469389
Structure, toxicity and antibiotic activity of gramicidin S and derivatives.
(2016)
PMID: 26886453

Related Peptides

Tyrothricin

Peptide

2 shared conditions · 6 outcomes

Tyrothricin is a cyclic peptide antibiotic complex from Bacillus brevis - the first peptide antibiotic used in humans (1939). Contains 60-80% tyrocidine (cyclic decapeptides) and 20-40% gramicidin (linear peptides). Over 60 years of clinical use with no significant resistance reported. RCT (DoriPha, n=321): Tyrothricin lozenges showed 64% improved complete remission vs placebo at 72 hours for acute pharyngitis. Used topically for sore throat, skin infections. SAFETY CONCERN: Systemic toxicity limits to topical/local use only.