Spectinomycin

Approved Indications:

• Uncomplicated Gonorrhea:
• Treatment of uncomplicated Neisseria gonorrhoeae infections of the urethra (men) and cervix (women) in penicillin-allergic patients or where penicillin/tetracycline resistance exists.
• Rectal Gonorrhea (off-label):
• Used in the treatment of rectal gonococcal infections, particularly in men, when first-line agents are contraindicated or ineffective.
• Ophthalmia Neonatorum (off-label):
• Occasionally used as part of multi-drug regimens in neonatal gonococcal conjunctivitis in penicillin-allergic settings.
• Pelvic Inflammatory Disease (off-label):
• Can be used as part of combination therapy for gonorrhea-associated PID when cephalosporins are contraindicated.

Adults:

• Uncomplicated Gonorrhea:
  2 grams IM (intramuscularly) as a single dose.
  Administer deeply into the gluteal muscle.

Pediatrics (off-label):

• Not routinely recommended due to limited pediatric data. Use may be considered for gonococcal conjunctivitis in neonates under specialist guidance.

Elderly:

• No dose adjustment necessary unless renal impairment is present.

Renal Impairment:

• Use with caution; no formal dosage adjustment, but clinical monitoring recommended in severe renal dysfunction.

Hepatic Impairment:

• No dose adjustment required; not significantly hepatically metabolized.

Administration Notes:

• Intramuscular use only.
• Do not administer intravenously.
• Shake vial well if reconstitution is required.

Spectinomycin acts by inhibiting bacterial protein synthesis. It binds to the 30S subunit of the bacterial ribosome, blocking the translocation step during translation. This action prevents peptide chain elongation, halting protein synthesis and leading to bacterial cell death. Unlike aminoglycosides, Spectinomycin does not cause misreading of mRNA, and its activity is primarily bacteriostatic, though it may be bactericidal at higher concentrations against Neisseria gonorrhoeae.

• Absorption: Rapidly absorbed after IM injection; peak plasma levels in ~1 hour.
• Bioavailability: Nearly 100% (IM).
• Distribution: Wide distribution in body fluids, especially in genital tract secretions.
• Protein Binding: ~30%.
• Metabolism: Not significantly metabolized; remains largely unchanged.
• Elimination: Primarily excreted unchanged in urine via glomerular filtration.
• Half-life: Approximately 1.5 to 3 hours.
• Onset of Action: Clinical improvement typically seen within 1–2 days.

• Pregnancy:
  FDA Pregnancy Category B
  Animal studies have not shown fetal risk, and no controlled human studies show risk. May be used during pregnancy if clinically indicated.
• Lactation:
  Spectinomycin is excreted in small amounts into breast milk. However, the concentration is low, and adverse effects on nursing infants are unlikely. Caution is advised, especially in neonates or premature infants.

• Primary Class: Antibiotic
• Subclass: Aminocyclitol antibiotic (closely related structurally to aminoglycosides but with a different mechanism and toxicity profile)
• Use Class: Gonorrhea-specific antibacterial (alternative agent)

• Known hypersensitivity to spectinomycin or any component of the formulation
• Use in patients with severe renal impairment without close monitoring
• Intravenous use (not approved; only for intramuscular injection)

• Use with caution in renal impairment, as the drug is renally excreted.
• May mask symptoms of other sexually transmitted infections—test for syphilis, HIV, and chlamydia before or alongside treatment.
• Not effective against pharyngeal gonorrhea—avoid in such cases.
• Superinfection risk: Prolonged use may promote fungal or bacterial overgrowth.
• Monitor for signs of anaphylaxis in penicillin-allergic patients despite being a different class.

Common (≥1%):

• Injection site reactions (pain, soreness, induration)
• Fever
• Nausea or vomiting

Uncommon:

• Dizziness
• Rash or urticaria
• Diarrhea
• Chills

Rare but Serious:

• Anaphylaxis or severe allergic reaction
• Stevens-Johnson Syndrome (extremely rare)
• Eosinophilia

Timing: Most adverse effects occur within 24–48 hours of dosing and are usually mild and self-limiting.

• No major drug-drug interactions known.
• May have additive nephrotoxicity if combined with other nephrotoxic agents (e.g., aminoglycosides, vancomycin).
• No CYP450 enzyme involvement—low risk of metabolic interactions.
• Alcohol: No direct interaction, but avoidance is generally recommended in the presence of infection or antibiotic therapy.

• WHO Guidelines: Spectinomycin is retained as a second-line treatment for gonorrhea in patients allergic to cephalosporins or where resistance to first-line agents is documented.
• CDC (U.S.) 2024 STI Guidelines: Now rarely used due to increasing resistance patterns and limited efficacy in pharyngeal infections. Reserved for specific cases when cephalosporins are contraindicated.

• Store at: 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C–30°C.
• Protect from light.
• Do not freeze.
• Reconstituted solutions should be used promptly; if storage is necessary, refrigerate and use within 24 hours.
• Shake vial well before use if suspension separates.