Fosfomycin Tromethamine

Pronunciation

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.

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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.

Copyright © 2009 Wolters Kluwer Health.

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