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Fosfomycin (disodium) Intravenous for Adults
Who can administer
May be administered by registered competent doctor or nurse/midwife
Important information
- Restricted antibiotic: the INTRAVENOUS route is reserved for serious infections with limited treatment options, following approval by microbiology/infectious diseases/CF consultant. It is usually used in combination therapy.
- Note: the vials are labelled as containing 4g in 100ml - however- they actually contain 4g drug powder, which then needs reconstitution and dilution to 100ml
- See under 'Dose' for adjustments required in renal impairment
- Unlicensed for use in cystic fibrosis
- A low sodium diet is recommended during treatment with Fosfomycin (56mmol sodium per 4g dose)
Available preparations
Fomicyt 4g vial
Reconstitution
Glucose 5% ONLY (see further information below)
- Reconstitute 4g vial with 20ml diluent removed from a 100ml infusion bag
- The vial will warm slightly upon reconstitution
- Once dissolved, transfer the reconstituted solution to the above infusion bag to produce a 4g in 100ml infusion
Methods of intravenous administration
Intermittent intravenous infusion
- Administer 2g dose over at least 15 minutes
- Administer 4g dose over at least 30 minutes
- Administer 8g dose over at least 60 minutes
Dose in adults
Usual dose (ref 1,3)
| Indication | Daily dose |
|---|---|
| Cystic fibrosis (unlicensed)(ref 2) | 4g every six hours |
| Complicated urinary tract infection | 8g every twelve hours |
| Nosocomial lower respiratory tract infection | 8g every eight hours |
| CPE infection (adults) in combination with other antimicrobials | See page 39 of National Guidelines |
Maximum 8g per dose
Elderly patient: Use usual recommended dose. Reduce dose if evidence of renal impairment
| Renal impairment FOR CYSTIC FIBROSIS (ref 2) | |
|---|---|
| Use with GREAT CAUTION in patients with renal impairment. Discuss with Micro/ID/CF consultant before using in any patient with renal impairment. | |
| eGFR (ml/min/1.73m2) | Recommended dose |
| 30 to 40 | 8g loading dose, then 4g every eight hours |
| 20 to 30 | 6g loading dose, then 3g every eight hours |
| 10 to 20 | 4g loading dose, then 2g every eight hours |
| less than 10 | 2g loading dose, then 1g every eight hours |
| Intermittent haemodialysis | 2g loading dose, then 2g at the end of each dialysis session |
| Renal impairment for indications NOT cystic fibrosis (ref 1,3) | ||
|---|---|---|
| Use with GREAT CAUTION in patients with renal impairment. Discuss with Micro/ID consultant before using in any patient with renal impairment. | ||
| eGFR (ml/min/1.73m2) | UTI | Other infections |
| 30 to 40 | 8g loading dose, then 6g bd | 8g loading dose, then 8g bd |
| 20 to 30 | 8g loading dose, then 4g bd | 8g loading dose, then 6g bd |
| 10 to 20 | 6g loading dose, then 3g bd | 8g loading dose, then 4g bd |
| less than 10 | 6g loading dose, then 3g od | 8g loading dose, then 4g od |
| Intermittent haemodialysis | 2g loading dose, and then 2g at the end of each dialysis session | |
| Continuous renal replacement therapy (RRT) | Post-dilution CVVHF - give usual dose. Pre-dilution CVVHF or other forms of RRT: no clinical data | |
Hepatic impairment: No dosage adjustment necessary
Monitoring
- Monitor electrolytes (sodium and potassium) due to sodium content (each 4g dose contains 56mmol sodium)
- Monitor fluid balance
Further information
- Water for Injection can be used as a diluent - however, it may not be practical to administer the drug in 100ml Water for Injection
Storage
Store below 250C
References
1:Fomicyt SPC Oct 2021
2: Nottingham University Hospitals: Adult Cystic Fibrosis Intravenous Antibiotic Dosing and Administration Guideline May 2020, together with email correspondence 4th Nov 2021
3: Dosage schedules simplified, as agreed with Dr Una Ni Riain, Microbiologist 26/3/2015
Therapeutic classification
Antibiotic
IV Guide Type