Drug therapy / treatment options for the management of PE / DVT

This section does not cover drug therapy and treatment of PE / DVT in pregnancy.  See separate GGC Thromboembolic Disease in Pregnancy and the Puerperium guideline for treatment in pregnant patients.

Guidance in this section covers: 

• Subcutaneous LMWH 
• Unfractionated heparin 
• Direct oral anticoagulants (DOACs)
• Warfarin 

It may be useful to refer back to the following pages: 

• Diagnosis and treatment of venous thromboembolism (VTE)
• Investigation and management of Deep Vein Thrombosis 
• Investigation and management of Pulmonary Embolism 

Subcutaneous LMWH

Enoxaparin is used for the initial treatment of VTE. It should be used for most patients, although ambulatory care patients may have treatment initiated with apixaban.

The enoxaparin dosage regimen should be based on an individual assessment of thrombosis risk, bleeding risk and renal function. See Table 1 for suggested regimens.

Table 1 – Enoxaparin dosing regimens

Patients with active cancer

• Most patients with active cancer can be treated with a DOAC.
• For those who require LMWH prescribe: enoxaparin 1mg/kg twice daily for 7 days (can consider 5-10 days on an individual basis), then switch to 1.5mg/kg once daily for the remainder of the course; see guideline Treatment and Secondary Prophylaxis of Venous Thrombosis in Patients with Malignant Disease for more information.
• In patients with high body weight or who develop VTE while anticoagulated, consider continuing 1mg/kg twice daily dosing for the rest of the course. For complex patients, or if concerns regarding compliance, seek specialist advice.

Patients with increased bleeding risk

Patients in the immediate period after stroke or surgery, and where there are more than the usual concerns around bleeding risk, could be considered for 1mg/kg twice daily in the short term and then returned to 1.5mg/kg once daily once the bleeding risk has passed.

Continue with treatment dose of enoxaparin until:

• The diagnosis is disproved - change to prophylactic dose if clinically appropriate.
• The diagnosis is confirmed:
  • Stop enoxaparin and start apixaban when the next scheduled dose is due - see below for apixaban dosing.
  • If apixaban is not suitable, prescribe an alternative oral anticoagulant.
  • If prescribing warfarin, overlap with enoxaparin for at least 5 days and until the INR has been ≥2 for two consecutive days.
  • If not suitable for an oral anticoagulant, complete the treatment course using enoxaparin.

Unfractionated Heparin (Heparin Sodium)

• Used in the treatment of DVT / PE if rapid anticoagulation is deemed appropriate (e.g. massive PE) or in patients thought to be at particularly high bleeding risk (e.g. recent surgery / trauma)
• There are different concentrations of unfractionated heparin currently available – only the 1000units/ml preparation should be used at all times
• Loading Dose: 5000units by IV bolus over 5 minutes (if 50kg - 100kg*) – use one 5ml vial of 1000units/ml (total concentration 5000units/5ml)
• Maintenance Infusion: 18units/kg/hour (if <100kg*) which is usually ∼1200units (1.2ml) per hour for a 70kg patient. If patient is at high risk of bleeding, start at 1000units/hour. Use one 20ml vial of 1000units/ml (total concentration 20,000units/20ml). Replace the syringe at least every 24 hours, until treatment is discontinued.
• Monitoring – Check APTT ratio after 6 hours, and 4 hours after any change in infusion rate, then daily.
• Adjust infusion rate according to APTT ratio (see table 5 below).

*Note: If <50kg or >100kg - see GGC guideline for heparin dosing details.

Table 5 – Unfractionated heparin dose adjustment

NOTES

• Monitoring - check APTT ratio 4 hours after any change in infusion rate.
• Rarely should patients require infusion rates >1.6–2ml/hour. If target APTT ratio of 1.8–2.8 is not being achieved with a dose of 1.6ml/hour, then monitor anti-factor Xa level (target 0.35–0.7units/ml).
• Routine platelet count monitoring for Heparin Induced Thrombocytopenia is not required unless unfractionated heparin is being administered within 3 months of recent surgery.

Direct Oral Anticoagulants (DOACs)

Apixaban is currently the NHSGGC preferred DOAC for acute treatment and long-term secondary prevention of DVT and/or PE. Rivaroxaban remains on the formulary as an alternative option for acute treatment of DVT and/or PE where it is considered more appropriate for an individual patient.

Apixaban and rivaroxaban are oral direct factor Xa inhibitors and dabigatran is an oral direct factor IIa inhibitor. All three have shown to be as effective as LMWH, followed by warfarin, in the treatment of acute PE and/or DVT. No monitoring of the anticoagulant effect of any of these medications is required. Reversal agents are available for apixaban and rivaroxaban (andexanet alfa, Ondexxya^®), and dabigatran (idarucizumab, Praxbind^®), see here for more information.

Patients with acute PE and/or DVT deemed suitable for apixaban therapy

• Used after treatment with LMWH once the diagnosis has been objectively confirmed. Initial treatment with apixaban can be considered if patient is being managed in ambulatory care.
• Apixaban is not recommended if CrCl is <15ml/minute, and should be used with caution if CrCl is 15–29ml/minute.
• Start apixaban 22–24 hours after the last dose of enoxaparin.
• Give a loading dose of apixaban* oral 10mg twice daily for the first 7 days and then 5mg twice daily for the remaining duration of acute treatment (i.e. 3 or 6 months).
• If for long-term anticoagulation, the dose of apixaban should be reduced to 2.5mg twice daily after 3-6 months.

*Note: If switching to apixaban after the patient has received a minimum of 7 days of therapeutic LMWH dose, then commence on apixaban oral 5mg twice daily (no loading dose is required). If less than 7 days of therapeutic LMWH dose has been given, then commence on apixaban loading dose for 7 days then the reduced dose as detailed above.

Exclusions to apixaban treatment 

• Creatinine clearance <15ml/minute
• Liver disease associated with cirrhosis or coagulopathy
• Pregnancy or breastfeeding
• Concurrent therapy with azole anti-fungal agents (except for fluconazole), protease inhibitors or strong CYP3A4 inducers (e.g. rifampicin, phenytoin, carbamazepine, phenobarbital or St John's Wort)
• Patients perceived to be at high bleeding risk who would not be suitable for any therapeutic anticoagulant therapy.
• Not recommended in patients weighing >150kg due to lack of evidence.

Patients being discharged on apixaban

• The initial 21 days of treatment (56 x 5mg tablets: 10mg twice daily for 7 days followed by 5mg twice daily for 2 weeks) should be provided from the hospital pharmacy.
• Patients on apixaban do not require referral to an anticoagulant clinic.
• The immediate discharge letter (IDL) should contain clear written information for the GP regarding the duration of treatment and any secondary care follow up.
• Any patient commenced on apixaban should be issued with an apixaban Patient Alert card and offered counselling about this anticoagulant medication.

Warfarin

• Used as follow-on from LMWH in the treatment of DVT and PE for patients not suitable for a DOAC.
• Excluded in pregnant patients, patients who inject drugs and cancer patients.
• Induction treatment with warfarin should always follow a validated induction dosing algorithm suitable to the patient and be accompanied by INR testing on the specified days.
• The age-adjusted Fennerty regimen algorithm (see Warfarin Induction for Inpatients) is suitable for most inpatients who need to quickly achieve a therapeutic INR of 2–3. Daily INR testing is required with this algorithm.
• The protocol gives dosing advice for the first 4 days of warfarin initiation only. From day 5 onwards, dosing should be based on clinical assessment and judgement.
• The use of alternative 'slower' induction regimens (with less intense monitoring) should be considered in outpatients and the elderly (see Warfarin Induction for Outpatients).
• Warfarin should be administered orally, once daily at 6pm.
• All patients must be referred to GCAS (Glasgow and Clyde Anticoagulation Service); see guideline and refer via TrakCare referral. 
• Any patient commenced on warfarin should be issued with a yellow anticoagulant booklet and offered counselling about the medication.

Guideline reviewed: July 2026

Page updated: July 2026