Fosfomycin Sodium

Fosfomycin exerts a bactericidal effect on proliferating pathogens by preventing the enzymatic synthesis of the bacterial cell wall. Fosfomycin inhibits the first stage of intracellular bacterial cell wall synthesis by blocking peptidoglycan synthesis.

The daily dose of Fosfomycin is determined based on the indication, severity and site of the infection, susceptibility of the pathogen(s) to fosfomycin and the renal function.In children,it is also determined by age and body weight.

Adults and adolescents >12 years of age (>40 kg): Fosfomycin is primarily excreted renally unchanged. The general dosage guidelines for adults with estimated creatinine clearance >80 ml/min are as follows:

• Osteomyelitis: 12-24 gm in 2-3 divided doses
• Complicated urinary tract infection: 12-16 gm in  3 divided dose
• Nosocomial lower respiratory tract infection: 12-24 gm in 2-3 divided dose
• Bacterial meningitis: 16-24 gm in 3-4 divided doses

Individual doses must not exceed 8 gm. The high-dose regimen in 3 divided doses should be used in severe infections expected or known to be caused by less susceptible bacteria. There are limited safety data in particular for doses in excess of 16 g/day. Special caution is advised when such doses are prescribed.

Dosage in renal insufficiency: Special precaution should be exercised if doses at the higher end of the recommended range are considered. In patients with impaired renal function the dose of fosfomycin must be adjusted to the degree of renal impairment.

Hepatic impairment: There are no data indicating that dose adjustment is necessary in patients with hepatic impairment.

Elderly patients: The recommended doses for adults should be used in elderly patients. Caution is advised when considering the use of doses at the higher end of the recommended range.

Pediatric population: Dose recommendations are based on very limited data.

Neonates, infants and children <12 years of age (<40 kg): The dosage of fosfomycin in children should be based on age and body weight (BW):

• Premature neonates (age <40 weeks): 100 mg/kg BW in 2 divided doses
• Neonates (age 40-44 weeks): 200 mg/kg BW in 3 divided doses
• Infants 1-12 months (up to 10 kg BW): 200-300 b mg/kg BW in 3 divided doses
• Infants and children aged1-12 years (10-40 kg BW): 200-400 b mg/kg BW in 3-4 divided doses

Method of administration: Fosfomycin Sodium is intended for intravenous administration. The duration of infusion should be at least 30 minutes for the 4 gm pack size. Use only clear solutions.

Preparation of the solution for infusion: Fosfomycin Sodium must be reconstituted and diluted prior to administration. Water for Injections and Glucose Infusion 50 mg/ml (5%) or Glucose Infusion 100 mg/ml (10%) may be used as solvent for the reconstitution and dilution. Sodium Chloride containing solvents must not be used.

Reconstitution: Shake the vial prior to the reconstitution to loosen up the powder. Reconstitute the 4 gm vials with 20 ml of solvent. Shake well to dissolve. A slight degree of warming occurs when the powder is dissolved.

Dilution: Transfer the reconstituted contents of 4 gm vials into an infusion container with further 80 ml of solvent. The resulting solution for infusion is clear and colorless to slightly yellowish.

Duration of treatment: Treatment duration should take into account the type of infection, the severity of the infection as well as the patient's clinical response.

No drug-drug interaction studies have been performed with fosfomycin.

Hypersensitivity to the active substance, fosfomycin, or to any of the excipients.

The most commonly reported adverse reactions during treatment are gastrointestinal disturbances and injection site reactions. Other important adverse reactions include hypokalaemia and/or hypernatraemia.

• To avoid potential development of cross resistance co-administration of Fosfomycin with other antibiotics is preferred.
• A high sodium load associated with the use of fosfomycin may result in decreased levels of potassium in serum or plasma. A low-sodium diet is recommended during treatment. The substitution of potassium may be necessary in some cases. Serum electrolyte levels and water balance must be monitored during therapy. Caution is advised when fosfomycin is used in patients with cardiac insufficiency, hypertension, hyperaldosteronism, hypernatraemia or pulmonary edema.
• Acute, potentially life-threatening hypersensitivity reactions (anaphylactic shock) may occur in very rare cases. At the first signs (including sweating, nausea, cyanosis), the infusion of fosfomycin must be immediately discontinued.

No clinical data on pregnancies are available. Fosfomycin should therefore not be prescribed to pregnant women unless the benefit outweighs the risk. After the administration of Fosfomycin, low quantities of fosfomycin were found in human milk. Fosfomycin should therefore not be administered during lactation unless the benefit outweighs the risk.

Experience regarding the overdose of fosfomycin is limited. Cases of hypotonia, somnolence, electrolytes disturbances, thrombocytopenia and hypoprothrombinemia have been reported with parenteral use of fosfomycin.

Intracellular antibiotic

Store below 30° C temperature, protect from light & moisture. Keep out of the reach of children. After being mixed with solvent this medicine should be used immediately or stored in a refrigerator (at 2-8°C) protected from light for up to 24 hours.