Drug information of Spiramycin


Drug group:

Spiramycin is a macrolide antimicrobial agent with activity against gram-positive organisms.
Spiramycin also has activity against some gram-negative bacteria.
Spiramycin also has activity against other organisms, including Mycoplasma, Chlamydia, Toxoplasma, Legionella and spirochetes
Toxoplasmosis (treatment)1—Spiramycin is used as an alternative agent in the treatment of toxoplasmosis during pregnancy.
Although spiramycin is effective in the treatment of some bacterial infections, spiramycin is considered to be a secondary agent and other medications are generally used in place of spiramycin.

Mechanism of effect

The mechanism of action of spiramycin is not clear ; however, it is thought to inhibiting protein synthesis and subsequent cell growth. It is primarily bacteriostatic, but may be bactericidal against more sensitive strains when used in high concentrations.


spiramycinis thought to reversibly bind to the 50 S subunit of bacterial ribosomes, resulting in blockage of the transpeptidation or translocation reactions, inhibiting protein synthesis and subsequent cell growth.


Absorption: The absorption of spiramycin is incomplete , with an oral bioavailability of 33 to 39% (range, 10 to 69%).The rate of absorption is slower than that of erythromycin and is thought to be due to the high pKa (7.9) of spiramycin , suggesting a high degree of ionization in the acidic stomach.
The rate of absorption is slower than that of erythromycin Studies have shown that administration with food reduces bioavailability by approximately 50% and delays the time to peak serum concentration.

Distribution: Spiramycin is highly concentrated in tissues. Spiramycin crosses the placenta and is distributed into breast milk. Spiramycin does not cross the blood-brain barrier.

Protein binding: Low (10 to 25%).
Biotransformation: Spiramycin metabolism has not been well studied ; however, spiramycin is thought to be metabolized in the liver to active metabolites.

Young persons (18 to 32 years of age): Approximately 4.5 to 6.2 hours.
Elderly persons (73 to 85 years of age): Approximately 9.8 to 13.5 hours.
Oral: 5.5 to 8 hours.

Elimination: Fecal—Biliary elimination is substantial , with over 80% of an administered dose excreted in the bile; enterohepatic recycling may occur. Renal—Urinary excretion accounts for only 4 to 14% of an administered dose.

Drug indications



Note: Dosing of spiramycin may be expressed as either milligrams (mg) or International Units (IU). One mg of spiramycin is equivalent to approximately 3000 IU.
Oral, 1 to 2 grams (3,000,000 to 6,000,000 IU) two times a day ; or 500 mg to 1 gram (1,500,000 to 3,000,000 IU) three times a day . For severe infections, the dose may be increased to 2 to 2.5 grams (6,000,000 to 7,500,000 IU) two times a day.

Note: Toxoplasmosis in pregnant women
First trimester: Oral, 3 grams (9,000,000 IU) per day, divided into three or four doses.
Second and third trimesters: Oral, 25 to 50 mg of pyrimethamine per day in combination with 2 to 3 grams of sulfadiazine per day and folinic acid 5 mg per day for three weeks, alternating with 3 grams (9,000,000 IU) of spiramycin , divided into three or four doses, for three weeks.

Usual pediatric dose
- Antibacterial - Children 20 kg of body weight and over: Oral, 25 mg (75,000 IU) per kg of body weight two times a day, or 16.7 mg (50,000 IU) per kg of body weight three times a day.


Patients with hypersensitivity reactions to other macrolides (e.g., erythromycin, azithromycin, clarithromycin, troleandomycin, dirithromycin, josamycin) may also have hypersensitivity to spiramycin .

Points of recommendation

» Taking on an empty stomach
» Compliance with full course of therapy
» Importance of taking medication on regular schedule and not missing doses
» Continue medicine for full time of treatment
» Proper dosing
Missed dose: taking as soon as possible; not taking if almost time for next dose; not doubling dose

Pregnancy level

Safe - has not been found to be teratogenic

Related drugs

Erythromycin , Clarithromycin

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