Blood drugs Flashcards
Anticoagulant overall indications
Therapeutic for VTE
Prophylactic for DVT/PE and stroke prevention e.g. in AF/ prosthetic heart valve
LMWH usage
Dalteparin, enoxaparin, tinzaparin inactivate factor Xa (but not thrombin)
Prevention/ initial VTE treatment
Given 1/2x daily SC, decrease dose in renal failure + prophylaxis
Unfractionated heparin usage
IV/SC
Binds antithrombin and improves its activity, binds Ca and IXa
Rapid onset and short 1/2 life
Monitor + adjust dose with APTT
Contraindications heparin
Bleeding disorders Platelets <60 Previous heparin induced thrombocytopenia Peptic ulcer/ cerebral haemorrhage Severe HT
Warfarin usage
Inhibits reductase which regenerates active form of vit K
Used PO OD as long-term anti-coagulation with INR monitored
Warfarin tablets doses
White 0.5mg
Brown 1mg
Blue 3mg
Pink 5mg
Warfarin INR targets
PE/DVT 2-3 or 3.5 if recurrent
AF 2-3
Aortic valve prosthetic 2-3, mitral 2.5-3.5
Duration of anticoagulation in DVT/PE
3 months for provoked
6 for unprovoked/ life-threatening extensive clots
When and how to reverse warfarin
INR>8 with minor bleed or any major bleed
Vit K for minor
Prothrombin complex concentrate 50u/kg for major
Issues with prednisolone
Long-term steroids >3wks stopped suddenly cause Addisonian crisis due to adrenal insufficiency, taper
TB, HT, chicken pox, osteoporosis + diabetes made worse by steroids
Growth retardation in young pt/ foetus in pregnant women
Efficacy reduced by anti-epileptics + rifampicin
Issues with azathioprine
Mercaptopurine + it’s prodrug azathioprine metabolised by xanthine oxidase, so toxicity if given with allopurinol
Weekly monitoring of FBC, U+Es, creatine, LFT needed for first couple of mths
SE: diarrhoea, abdo pain, marrow suppression, pancreatitis, nephritis
Ciclosporin/tacrolimus issues
Calcineurin inhibitors main issue is dose related nephrotoxicity so monitor, reduce dose if creatinine >30% increased over 2 measurements
SE: tremor, oedema, seizures, hepatotoxicity, skin cancer
Ciclosporin/tacrolimus interactions
Potentiated by: ketoconazole, diltiazem, verapimil, OCP, erythromycin, grapefruit
Inhibited by: barbiturates, carbamazepine, phenytoin, rifampicin
Avoid nephrotoxics in combo
Methotrexate MOA
Inhibits dihydrofolate reductase so purine/pyrimidine synthesis reduction
Cyclophosphamide MOA
Binds to DNA, cross links to RNA so reduced protein synthesis
