Gramicidin is a drug in the antibiotic class of drugs. It is isolated from the bacterium Bacillus brevis.
What is gramicidin?
Gramicidin is a peptide antibiotic, mainly used to treat infections of the skin, nose, ears, and eyes. Gramicidin is a peptide antibiotic administered primarily in combination preparations. The drug is used to treat infections of the skin, nose, ears and eyes. It has a length of 15 amino acids and is available in two different forms. Gramicidin D is a mixture of gramicidin A, B and C. The active ingredient belongs to the pentadeka peptides. Gramicidin S, on the other hand, is a cyclic deca-peptide. Gramicidin D was isolated from the bacterium Bacillus brevis in the 1940s by the French-American physician and microbiologist René Dubos. In 1944, Georgi Gause also succeeds in isolating it from bacterial culture supernatant. Gramicidin D is produced via the bacteria‘s nonribosomal peptide synthesis. Tyrothricin is a naturally occurring mixture of gramicidin and tyrocidin. The mixture is used to treat infections of the mouth and throat. Tyrothricin is also used to treat wounds.
Pharmacological action
Gramicidin D deposits lipophilic molecules into the cell wall of bacteria. Two molecules of the drug at a time form a tunnel channel between the extracellular space and the cell interior. Monovalent cations such as potassium can pass through this tunnel. However, divalent cations and anions cannot pass through the tunnel. This results in an unregulated flow of ions in the cell. The flow depends on the respective electrochemical gradients and concentration gradients. Finally, the bacteria die due to the uncontrolled ion flow. Depending on the concentration of the administered gramicidin, the membrane fluidity may decrease or the membrane may be completely destroyed. Gramicidin D is thus harmful to both eukaryote and prokaryote cells.
Medical application and use
The drug is sold primarily in combination preparations. These are applied particularly to the ears, nose, skin, and eyes. Possible dosage forms include lozenges, ointments, creams, eye drops, and ear drops. Gramicidin is used almost exclusively for local antibiosis. The substance is only suitable to a limited extent for systemic antibiosis. Preparations containing gramicidin are administered especially in cases of inflammation of the nasal mucosa. Such rhinitis can be chronic or acute. Typical pathogens of infectious rhinitis are Haemophilus influenzae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus or pneumococci. In contrast, gramicidin is not effective for allergic rhinitis. Allergic rhinitis is not caused by bacteria, but by an exaggerated reaction of the immune system. Antibiosis with gramicidin is particularly indicated when the sinuses are also inflamed as part of the rhinitis. Rhinosinusitis is accompanied by severe headache and carries the risk of perforation with abscess formation in the maxillary sinus or orbit. Gramicidin is also often the agent of choice for bacterial infections of the skin. Bacterial infections of the skin are usually caused by staphylococci or streptococci. A typical bacterial infection of the skin is impetigo contagiosa. It is also known as grind lichen and occurs predominantly in childhood. Honey-yellow crusts are typical of the disease. Gramicidin is also used in medical and biochemical research. Here it is used in the patch-clamp technique for the electrophysiological examination of cells.
Risks and side effects
Gramicidin should not be used if there is a possibility that the antibiotic will come into contact with the cerebrospinal fluid and/or meninges. Otherwise, damage to the structures may occur. In rare cases, allergic skin changes such as exanthema, itching, redness and rash may occur. Swelling of the eyelids is also observed. If there is no improvement in symptoms within five days of using gramicidin, the doctor must be consulted. It could be a superinfection with therapy-resistant bacteria or fungi. This must be responded to with a modified therapy.Improper use and high-dose long-term use of ear drops containing gramicidin may cause hearing damage. Rarely, renal dysfunction may also occur. When used as directed, interactions of gramicidin with other agents are not known.
