1. Clinical Overview
Kanamycin is a bactericidal aminoglycoside antibiotic derived from *Streptomyces kanamyceticus*. It is primarily used for the treatment of serious infections caused by susceptible aerobic gram-negative bacteria and mycobacteria, particularly in the context of multidrug-resistant tuberculosis (MDR-TB) in India. Its use is limited by significant ototoxicity and nephrotoxicity, requiring careful monitoring.
| Onset | Duration | Bioavailability |
|---|---|---|
| Rapid; peak serum concentrations are reached within 1 hour after intramuscular injection. | Approximately 8-12 hours, supporting a twice-daily dosing regimen in patients with normal renal function. | Poor (<1%) via oral route; nearly 100% via intramuscular (IM) injection. |
2. Mechanism of Action
Kanamycin binds irreversibly to the 30S ribosomal subunit of susceptible bacteria. This binding interferes with the initiation complex, misreads the mRNA code, and causes premature termination of protein synthesis. The result is bactericidal activity against actively dividing organisms.
3. Indications & Uses
- Pulmonary and extrapulmonary Multidrug-Resistant Tuberculosis (MDR-TB) as part of a combination regimen
- Serious infections caused by susceptible gram-negative bacilli (e.g., *E. coli*, *Klebsiella*, *Enterobacter*) when less toxic alternatives are contraindicated or ineffective
4. Dosage & Administration
Adult Dosage: For MDR-TB (IM): 15 mg/kg (typically 750mg to 1000mg) once daily or 5 days per week. Maximum single dose should not exceed 1 gram. For systemic infections (IM/IV): 15 mg/kg/day in divided doses every 8-12 hours.
Administration: Administered as a deep intramuscular injection into a large muscle mass (gluteal or lateral thigh). Rotate injection sites. For IV use, it must be diluted and infused over 30-60 minutes. Oral formulation is not absorbed and used only for gut sterilization.
5. Side Effects
Common side effects may include:
- Pain, induration, or sterile abscess at injection site
- Mild proteinuria, presence of casts in urine
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Furosemide / Ethacrynic Acid | Potentiates ototoxicity (additive damage to hair cells) | Major |
| Other Aminoglycosides (Gentamicin, Amikacin) | Increased risk of nephrotoxicity and ototoxicity | Major |
| Vancomycin | Increased risk of nephrotoxicity | Major |
| Cisplatin | Additive ototoxicity and nephrotoxicity | Major |
| Neuromuscular blocking agents (e.g., Succinylcholine) | Enhanced and prolonged neuromuscular blockade, risk of respiratory arrest | Major |
| Penicillins (e.g., Carbenicillin, Ticarcillin) | Physical inactivation of kanamycin if mixed in same IV line; may also have synergistic antibacterial effect in vivo. | Moderate |
7. Patient Counselling
- DO report any ringing in the ears (tinnitus), feeling of fullness in the ears, hearing loss, dizziness, or unsteady gait IMMEDIATELY.
- DO ensure you stay well-hydrated unless advised otherwise by your doctor.
- DO keep all scheduled appointments for hearing tests (audiometry) and blood tests (creatinine).
- DO NOT take any other medicines, including over-the-counter painkillers or supplements, without consulting your doctor.
- DO NOT miss doses if on TB treatment; adhere strictly to the regimen.
8. Toxicology & Storage
Overdose: Manifestations of overdose include severe ototoxicity (deafness, tinnitus, vertigo), nephrotoxicity (acute renal failure), and neuromuscular blockade (muscle weakness, respiratory depression or arrest).
Storage: Store in a cool, dry place, protected from light. The injection powder/vial should be stored below 25°C. After reconstitution with sterile water for injection, the solution is stable for 24 hours at room temperature or refrigerated. Do not freeze.