Methotrexate
The typical dose Regimen is :
7.5mg weekly increasing by 2.5mg every 6 weeks to a maximum of 25mg. Lower doses should be used in the frail elderly or if there is significant renal impairment. Regular folic acid supplements are thought to reduce toxicity.
Cotrimoxazole or trimethoprim must be avoided in patients taking methotrexate. Excess alcohol should be avoided. Live vaccines should be avoided in patients taking methotrexate. NSAIDs in addition to the above doses of methotrexate are not contraindicated. Annual ‘flu vaccine should be given.
Pretreatment assessment:- FBC, U&E's, creatinine, LFT's, Chest Xray.
Monitoring:- FBC fortnightly until 6 weeks after last dose increase and provided it is stable monthly thereafter. LFT's (incl. AST or ALT) with each blood test. U&E's 6-12 monthly (more frequently if there is any reason to suspect deteriorating renal function).
Action to be taken:
Withhold if:
WBC <4.0x10³/mm³
Neutrophils<2.0x10³/mm³
Platelets<150x10³/mm³
>2-fold rise in AST, ALT
(from upper limit of reference range)
Unexplained fall in albumin
Rash or oral ulceration
New or increasing dyspnoea or cough
MCV>105fl
investigate and if B12 or folate low
start appropriate supplementation
Significant deterioration in renal function
reduce dose
Abnormal bruising or sore throat
withhold until FBC result available
Please note that in addition to absolute values for haematological indices a rapid fall or a consistent downward trend in any value should prompt caution and extra vigilance.
Sulphasalazine (Salazopyrine EN)
The typical dose regimen is :
500mg/day increasing by 500mg weekly to 2.0-3.0g/day.
Pretreatment Assessment:
FBC, LFT's.
Monitoring:
FBC every two weeks and LFT's (incl. AST or ALT) 4 weekly for the first 12 weeks. FBC and LFT's (including ALT or AST) 12 weekly thereafter. If during the first year of treatment blood results have been stable 6 monthly tests will suffice for the second year and, thereafter, monitoring of blood for toxicity could be discarded. Patient should be asked about the presence of rash or oral ulceration at each visit.
Action to be taken:
Withhold treatment if :
- WB<4.0x10³/mm³
- Neutrophil <2.0x10³/mm³
- Platelets < 150x10³/mm³
- >2-fold rise in AST, ALT or Alk. Phos
(from upper limit of reference range)
- Rash or oral ulceration
withhold until discussed with Rheumatologist.
- MCV>105fl
investigate and if B12 or folate low start appropriate supplementation
- Nausea/dizziness/ headache
if possible continue, may have to reduce dose or stop if symptoms are severe.
- Abnormal bruising or sore throat
withhold until FBC result available
