interferon beta

CLINICAL USE

Treatment of relapsing, remitting multiple sclerosis

DOSE IN NORMAL RENAL FUNCTION

Interferon beta-1a:Avonex: 6 million IU (30 micrograms) once a weekRebif: 22–44 micrograms 3 times a week Interferon beta-1b:Betaferon: 8 million IU every second day

PHARMACOKINETICS

Molecular weight :18 500–22 500

%Protein binding :No data

%Excreted unchanged in urine : Negligible.

Volume of distribution (L/kg) :3

half-life – normal/ESRD (hrs) :5–10

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function Monitor renal function

10 to 20 : Dose as in normal renal function Monitor renal function

<10 : Use with caution due to risk of accumulation, and monitor renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Not dialysed. Dose as in GFR <10 mL/min

HD :Not dialysed. Dose as in GFR <10 mL/min

HDF/high flux :Dialysed. Dose as in GFR

<10 : mL/min

CAV/VVHD :Not dialysed. Dose as in GFR=10–20 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugsCiclosporin and tacrolimus: interferon reported to reduce the activity of hepatic cytochrome P450 enzymes

ADMINISTRATION

Reconstition

With diluent provided

Route

IM (Avonex), SC (Rebif, Betaferon)

Rate of Administration

–

Comments

Stable for 6 hours at 2–8 oC once reconstituted

OTHER INFORMATION

Pre-treatment with paracetamol is recommended to reduce incidence of flu-like symptomsVary the site of injection each week Rare cases of lupus erythematosus syndrome have occurredTransient increases in creatinine, potassium, urea, nitrogen and urinary calcium may occurInterferon up-regulates the cell surface presentation of class II histocompatibility antigens, which raises the possibility of drug-induced allograft rejection. There are numerous clinical reports of allograft rejection, acute renal failure and graft loss after interferon therapy. Hence extreme care should be exercised in the use of interferon after renal transplantationInterferon is metabolised primarily in the kidney. It is excreted in the urine, but is reabsorbed by the tubules where it undergoes lysosomal degradation. In patients undergoing haemodialysis, the interferon molecule may accumulate as it is too large to be dialysed and will not undergo renal degradation. Hence, the dose may need to be adjusted.

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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