Therapeutic Handbook - GGC Prescribing

IV Drug Misusers• Given their chaotic lifestyles and habits, these patients may be considered at high risk ofbleeding complications from therapeutic anticoagulant therapy, particularly warfarin therapywhich demands careful compliance with monitoring and avoidance of interacting drugs (includingalcohol).• For these patients an individualised risk / benefit assessment is required, and there are threepossible approaches to outpatient management of DVT in these patients:1. No anticoagulant therapy2. LMWH or oral rivaroxaban for 6 weeks3. Warfarin or rivaroxaban treatment for 3 - 6 monthsAn algorithm to inform the decision as to which treatment option is the most suitable and with detailsof treatment for related conditions (e.g. cellulitis) is available on StaffNet, Clinical Guideline ElectronicResource Directory and search in the 'Haematology' section.Screening for cancer in patients with unprovoked venous thrombosisIn patients over 40 years old, who have no ‘red flag’ signs for cancer that might warrant specifictargeted investigations, undertake screening urinalysis and CXR. Mammogram, in women, and CTabdomen and pelvis may be considered in high risk cases.Thrombophilia testingThrombophilia testing is warranted in some patients who experience a VTE but should not beperformed at the time of the acute event or during anticoagulation therapy.Drug therapy / treatment optionsSubcutaneous LMWH (see pages 80 - 82 for dosing in pregnant patients)Dalteparin is the LMWH of choice across NHSGGC for the initial treatment of VTE unless thepatient is pregnant or has specific contraindications to dalteparin (although some patients withacute PE and/or DVT may be considered for oral rivaroxaban) and most patients with cancershould continue treatment with LMWH for the duration that anticoagulation is required.Continue with dalteparin until:• The diagnosis is disproved or• The diagnosis is confirmed and either rivaroxaban is commenced or dalteparin has beenover-lapped with warfarin for at least 5 days and the INR has been > 2 for two consecutivedays.• Dalteparin does not require laboratory monitoring (APTT is inappropriate, though if significantrenal impairment or exceptionally low or high BMI, consider assessing anti-factor Xa activityafter 2 - 3 consecutive doses of dalteparin, at 4 hours post dose (when target would be0.5 - 1 units/ml)). Guidelines on appropriate use of LMWH at extremes of body weight andwith renal impairment (CrCl < 30 ml/minute) are available on StaffNet, Clinical GuidelineElectronic Resource Directory and search in the 'Haematology' section..Cardiovascular SystemContinues on next pagePage 75