Dalteparin is the brand of LMWH currently on the NHS Lothian Formulary.

• The therapeutic dose is 200 units/kg SC once daily.
• It is imperative that the patient is weighed and that the weight is documented on TRAK in the EPR section, observations and measurements.
• For VTE, start warfarin and continue dalteparin for at least 5 days and until the INR is greater than 2.0 on 2 consecutive days.
• For pregnant women with VTE refer to RCOG Guidelines and local obstetric guidelines for dosing, and the patient must be referred to the on-call obstetric team. Links are given on p5.

Dalteparin daily doses for treatment of VTE

Note: All pre-filled syringes listed below contain 25,000 units/mL.

• These are fixed-dose pre-filled syringes. Determine the required dose (dependent on patient’s weight and assuming normal bleeding risk) and select the appropriate pre-filled syringe. All patients should be weighed and weight in kilograms recorded in the patient’s case records/electronically on TRAK.
• Administer the full syringe contents by subcutaneous injection.
• Do not expel the air bubble from these pre-filled syringes before administration.
• The maximum dose: 18000 units SC daily. Note: in certain situations of acute life-threatening thrombosis, patients weighing over 120 Kg can be given a weight-based dose of dalteparin. This is an off-label approach and must be discussed with haematology.
• Patients receiving low molecular weight heparin (or unfractionated heparin) may require platelet monitoring. See p27.

If advice required please contact Haematology.

Patients with an underlying malignancy should be considered for continuation of LMWH rather than oral anticoagulation. However in those who do not want to inject, an oral Xa inhibitor (either apixaban or rivaroxaban) is a reasonable alternative. Edoxaban has recently been shown to be efficacious in this setting but may hold an increased risk of bleeding in gastro-intestinal and urological cancers, and drug-interactions with chemotherapy are unclear. Edoxaban is currently not yet on Formulary for this indication.

Compared to warfarin, LMWH carries a similar risk of bleeding but halves the recurrences in patients with cancer.

Full dose dalteparin (200 units/kg) is given for the first month; if continuing dalteparin after the first month the dose is reduced to 150 units/kg as detailed in the box below, unless the patient weighs less than 46kg, or over 98kg, when the dose is left unaltered. For patients with BMI greater than or equal to 40, discuss with haematology as LMWH anti-Xa levels may be required.

First month

Second month and onwards

At 3 months, review the patient to decide on subsequent management. If cancer is not cured some form of continuing anticoagulation is recommended. If this is with LMWH, there is no date to support if the dose can be reduced to a prophylactic dose.

Link to Edinburgh Cancer Centre protocol:

Dalteparin for extended treatment and prophylaxis of Venous Thromboembolism (VTE) in patients with solid tumours within the Edinburgh Cancer Centre.

http://intranet.lothian.scot.nhs.uk/Directory/ooqs-theoncologyonlinequalitysystem/documents/Dalteparinforcancerclots.pdf

If a patient is being discharged from hospital on LMWH the following information must be provided to the general practitioner:

• Indication for anticoagulation with LMWH
• Anticipated duration of anticoagulation
• Dose (units), frequency
• Weight (kg)
• Renal function

This is to ensure the safe ongoing prescription of LMWH after discharge.

LMWH does not require routine laboratory monitoring since weight-adjusted dosing for treatment, or thromboprophylaxis, provide a predictable clinical response.

Dosing may be unreliable in patients:

• at extremes of body weight: BMI less than/equal to 19 or BMI greater than/equal to 40
• with severe renal impairment (creatinine clearance less than 30ml/min) (see footnotes, Table H, p12 for thromboprophylaxis, and Table L, p23 for therapeutic dosing).
• during pregnancy (see RCOG guidelines and SCRH protocol) - links on p5.

In these situations there may be some merit in assessing LMWH activity.

LMWH activity should be measured if there is unexpected bleeding.

How to arrange a LMW heparin assay:

LMW Heparin levels are ordered on TRAK as “heparin assay” and click on LMWH; samples are sent in a green citrated tube filled adequately to the level marked on the tube. Samples must be couriered to the RIE haematology laboratory if the patient is being managed at other NHS Lothian sites.

A 24-hour service is available for this automated test and all requests should be discussed with the duty laboratory haematology biomedical scientist: extension 26093 or page 6550/via switchboard out-of- hours.

When to take a peak LMW heparin assay:

A peak LMW Heparin level should be taken after the third dose of LMWH has been administered, 3-4 hours following the administration of the drug.

Interpretation:

For patients on once daily dosing (therapeutic), the expected peak plasma concentration is about 1.0 anti-Xa units/ml (with a range of 0.5-1.5 anti-Xa units/mL for twice daily dosing).

For patients receiving thromboprophylaxis the expected peak plasma concentration is between 0.1-0.4 anti-Xa units/ml.

The duty haematologist can assist with dose adjustment if the level is sub-or supra-therapeutic.