Spiramycin

Approved Indications:

• Treatment and prophylaxis of toxoplasmosis, especially during pregnancy to prevent congenital infection
• Respiratory tract infections caused by susceptible bacteria (e.g., Streptococcus, Staphylococcus species)
• Soft tissue infections including skin and subcutaneous tissue infections
• Dental infections such as periodontitis and gingivitis
• Pertussis (whooping cough) in some countries as an alternative treatment
• Legionnaires’ disease (off-label)

Off-label (Clinically Accepted) Uses:

• Prevention of vertical transmission of Toxoplasma gondii in pregnant women
• Treatment of infections caused by atypical pathogens such as Mycoplasma pneumoniae and Chlamydia species
• Use in patients allergic to penicillin for certain infections

Adults:

• Usual oral dose: 1 to 3 million international units (IU) per day divided into 2–3 doses
• For toxoplasmosis prophylaxis in pregnancy: 3 million IU orally every 8 hours
• Duration varies depending on indication, typically 7 to 14 days for infections, longer for toxoplasmosis prophylaxis

Pediatrics:

• Dose based on body weight, generally 30–50 mg/kg/day divided into 2–3 doses
• Use under specialist guidance, especially in toxoplasmosis treatment

Elderly:

• No specific dose adjustment recommended; monitor renal and hepatic function

Special Populations:

• Hepatic impairment: Use with caution; monitor liver function
• Renal impairment: No dose adjustment usually needed due to hepatic metabolism

Administration:

• Oral route, with or without food
• Tablets or suspension formulations available

Spiramycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding reversibly to the 50S subunit of bacterial ribosomes. This binding blocks the translocation step of protein elongation, effectively inhibiting bacterial growth (bacteriostatic effect). Additionally, spiramycin concentrates intracellularly, which makes it effective against intracellular pathogens such as Toxoplasma gondii. It also accumulates in placental tissues, contributing to its use in preventing fetal infection.

• Absorption: Well absorbed orally; peak plasma concentrations achieved within 2–3 hours after administration
• Distribution: Widely distributed, with high concentrations in lung, liver, spleen, and placenta
• Metabolism: Metabolized in the liver to inactive metabolites
• Elimination: Primarily excreted via bile into feces; minimal renal excretion
• Half-life: Approximately 10 hours, allowing for twice or thrice daily dosing
• Bioavailability: Moderate due to first-pass metabolism

• Pregnancy: Generally considered safe and often used during pregnancy, especially for toxoplasmosis prophylaxis; classified as FDA Pregnancy Category B (no evidence of risk in humans)
• Lactation: Excreted in breast milk in low concentrations; generally considered safe, but caution advised

• Macrolide antibiotic

• Known hypersensitivity to spiramycin or other macrolide antibiotics
• Severe liver impairment
• Concomitant use with certain drugs that prolong QT interval (caution advised)

• Use with caution in patients with hepatic dysfunction; monitor liver function tests
• May prolong QT interval; caution in patients with cardiac arrhythmias or those taking other QT-prolonging drugs
• Monitor for signs of superinfection with prolonged use
• Avoid use in patients with known macrolide resistance in pathogens

Common:

• Gastrointestinal disturbances: nausea, vomiting, diarrhea, abdominal pain
• Taste disturbances
• Allergic reactions such as rash and pruritus

Rare/Serious:

• Hepatotoxicity, including cholestatic jaundice
• Cardiac arrhythmias (rare)
• Severe hypersensitivity reactions (very rare)

• CYP3A4 inhibitors or inducers: Spiramycin is metabolized by CYP3A4; interactions can alter its levels
• Other QT-prolonging drugs: Additive risk of cardiac arrhythmias
• Antacids and gastric acid suppressants: May reduce absorption of spiramycin; separate administration by at least 2 hours
• Warfarin: Potential to increase anticoagulant effect; monitor INR closely

• Updated guidelines emphasize spiramycin's role in toxoplasmosis prophylaxis during pregnancy to prevent congenital infection
• Increased caution advised regarding cardiac effects and potential drug interactions
• Recommendations favor spiramycin as a safe alternative in macrolide-sensitive infections in penicillin-allergic patients

• Store at 20°C to 25°C (68°F to 77°F)
• Protect from moisture and light
• Keep tablets in tightly closed containers
• Keep oral suspensions refrigerated if required, and shake well before use
• Do not freeze suspensions