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Fosfomycin Tromethamine

Pronunciation: foss-foe-MY-sin troe-METH-ah-meen
Class: Anti-infective, Antiseptic

Trade Names

Monurol
- Granules 3 g

Pharmacology

Interferes with bacterial cell wall biosynthesis.

Pharmacokinetics

Absorption

Absolute bioavailability is 37% while fasting; it is reduced 30% with food. C max is about 26 mcg/mL while fasting; about 17.6 mcg/mL with a high-fat meal. T max is 2 h, about 4 h with a high-fat meal.

Distribution

Mean Vd ss is about 136 L. Fosfomycin is 0% protein bound. It distributes to the kidneys, bladder wall, prostate, seminal vesicles, and crosses the placental barrier.

Elimination

About 38% is excreted in urine unchanged and about 18% from the feces. Mean t 1/ 2 is about 5.7 h.

Special Populations

Renal Function Impairment

The t 1/ 2 is 40 h in hemodialysis patients. Patients with Ccr 7 to 54 mL/min have a t 1/ 2 of 11 to 50 h, and urinary excretion decreases to 11%.

Indications and Usage

Treatment of uncomplicated UTI (acute cystitis) in women caused by susceptible strains of specific microorganisms.

Contraindications

Standard considerations.

Dosage and Administration

Adult Women

PO One 3 g sachet dissolved in 3 to 4 oz of cool water.

General Advice

  • Never take in dry form; always mix with water, but do not use hot water. Pour the entire contents of the single-dose sachet into 3 to 4 oz of water and stir to dissolve.
  • Administer immediately after mixing; may be taken with or without food.

Storage/Stability

Store dry powder at room temperature (59° to 86° F).

Drug Interactions

Metoclopramide

May decrease serum concentrations and urinary excretion of fosfomycin.

Laboratory Test Interactions

None well documented.

Adverse Reactions

CNS

Headache; dizziness.

Dermatologic

Rash.

EENT

Rhinitis; pharyngitis.

GI

Diarrhea; nausea; dyspepsia; abdominal pain.

Genitourinary

Vaginitis; dysmenorrhea.

Miscellaneous

Asthenia; back pain; pain.

Precautions

Pregnancy

Category B .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Elderly

No dosage adjustment necessary.

Single dose

Do not use more than 1 single dose to treat a single episode of infection.

Patient Information

  • Instruct patient in proper preparation of medication.
  • Inform patient that this is a single-dose treatment and repeated doses do not improve the clinical success.
  • Advise patient that symptoms should improve in 2 to 3 days after taking drug. If symptoms do not improve, instruct patient to contact health care provider.
  • Increase fluid intake to 2,000 to 3,000 mL/day.
  • Instruct the patient on proper personal hygiene to help prevent recurrence of infections.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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