Drug Breakdown / CPD

Drug Breakdown: Fosfomycin

02 June 2023
Prescribing
02 June 2023
Volume 5 · Issue 6

Abstract

In this column, Sharon Rees aims to refresh knowledge and interest in some of the commonly used drugs in a series of tweets. This month she is talking about #fosfomycin

Dr Sharon Rees @reesprescribe

Day 1: Originally derived from streptomyces bacteria (1960s), the main use for the synthetic oral form of #fosfomycin since the 1990s is for uncomplicated UTIs. Still available i.v for osteomyelitis, RTI & complicated UTIs

Dr Sharon Rees @reesprescribe

Day 2: #fosfomycin is used 2nd–3rd line for uncomplicated UTI as the oral formulation of #fosfomycin trometamol. This is a single dose therapy 3 g for those over 12yrs. SPC also states used for peri-operative prophylaxis in transrectal prostate biopsy in men. Granules are dissolved in water & taken stat

Dr Sharon Rees @reesprescribe

Day 3: #fosfomycin should be taken on an empty stomach at bedtime & after emptying bladder. There is no known drug metabolism. #fosfomycin is distributed into the urinary tract in high concentrations. Unchanged drug is excreted in urine for minimum 24 hrs, hence single dose. T½ ~ 6 hrs. This is prolonged in severe renal failure (do not use)

Dr Sharon Rees @reesprescribe

Day 4: #fosfomycin MOA is to inactivate the MurA enzyme needed for peptidoglycan/cell wall synthesis. Rapid bactericidal effect with low toxicity. Covers a wide spectrum of bacteria including some resistant organisms e.g MRSA, ESBL organisms & glycopeptide resistant enterococci

Dr Sharon Rees @reesprescribe

Day 5: #fosfomycin adverse drug effects (ADEs) for oral formulation. Common include GI effects e.g diarrhoea, vulvovaginitis & headache. Uncommon include vomiting, rash. Not known are antibiotic associated colitis, hypersensitivity reactions & angioedema (NOT exhaustive)

Dr Sharon Rees @reesprescribe

Day 6: #fosfomycin drug-drug interactions. There are none stated in BNF! SPC states metoclopramide lowers concentration & any drug which increases gut motility should be avoided. May affect INR

Dr Sharon Rees @reesprescribe

Day 7: There is growing interest in using #fosfomycin for multi-drug resistant infections. The unique structure & mechanism of action mean no/minimal cross-resistance & also low acquired resistance. There is known resistance to UTIs from staphylococcus saprophyticus

EARN YOUR CPD CERTIFICATE

With the help of Prescribing and Therapeutics Training Ltd and the Journal of Prescribing Practice, you can earn your 1-hour CPD certificate

In addition to the tweets, read the BNF treatment summary on urinary tract infections, the monograph on fosfomycin and the SPCs for Monuril (fosfomycin). Once you have completed this, answer the 10 questions. Submit your answers to reesprescribe@gmail.com. If you answer at least eight out of 10 questions correctly, you will receive your CPD certificate via email.

Further reading on #fosfomycin

  • Urinary tract infections : https://bnf.nice.org.uk/treatment-summaries/urinary-tract-infections/
  • Fosfomycin : https://bnf.nice.org.uk/drugs/fosfomycin/
  • Monuril : https://www.medicines.org.uk/emc/product/7329/smpc#gref
  • Fosfomycin is used as a one dose tablet to treat uncomplicated urinary tract infections (UTIs) TRUE or FALSE?
  • Originally, fosfomycin was derived from soil bacteria TRUE or FALSE?
  • Which of the following is TRUE?
  • Fosfomycin is typically used first-line for UTIs
  • Fosfomycin should be taken on an empty stomach
  • Fosfomycin should be used first-line in pregnancy for UTI
  • Fosfomycin is licensed for use in all age groups
  • Which of the following is NOT related to the single dose regimen for fosfomcyin?
  • High concentration of drug in the urinary tract
  • Duration of urinary tract contact with antibiotic over at least 24 hours
  • Extensive drug metabolism
  • Renal excretion
  • Fosfomycin is a broad spectrum antibiotic TRUE or FALSE?
  • Fosfomycin is bacteriostatic TRUE or FALSE?
  • Which of the following is TRUE?
  • Fosfomycin inhibits bacterial cell wall synthesis but by a different route to penicillins
  • Fosfomycin drills holes in the bacterial cell membrane
  • Fosfomycin blocks protein synthesis
  • Fosfomycin alters the osmotic balance in the cell and causes it to shrivel
  • There is currently minimal antibiotic resistance to fosfomycin TRUE or FALSE?
  • Fosfomycin is active against ESBL producing bacteria TRUE or FALSE?
  • Which of the following is a common adverse drug effect for fosfomycin?
  • Hypersensitivity reactions
  • Antibiotic associated colitis
  • Rash
  • Diarrhoea