What is the role of medications in the treatment of protein S deficiency?

Updated: Jan 03, 2021
  • Author: Mohammad Muhsin Chisti, MD, FACP; Chief Editor: Perumal Thiagarajan, MD  more...
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Answer

Heparin is used for patients with acute thrombotic events or for the prevention of thrombosis. Heparin treatment currently is available in two forms: unfractionated (standard) heparin or low molecular weight heparin (LMWH).

Unfractionated heparin for treatment of thrombosis is administered properly by a weight-based dosing protocol, with a target heparin therapeutic range as monitored by the activated partial thromboplastin time (aPTT) test and for a minimum of 5 days. A heparin dosing protocol includes the specified weight-dosing regimen, the target therapeutic aPTT range, the time for measuring aPTT tests after bolus or adjustment in dose (4-6 h), and a standard means of adjusting the unfractionated heparin infusion on the basis of the aPTT (eg, subtherapeutic, therapeutic, supratherapeutic).

A commonly used weight-adjusted unfractionated heparin regimen is termed 80/18, and consists of an 80 U/kg IV bolus followed by 18 U/kg continuous IV infusion. The target therapeutic heparin range is ideally individualized to the institution's laboratory aPTT test instrument and reagent.

To obtain an institutional heparin therapeutic range, employ a method such as that described by Brill-Edwards or any other similar comparison of in vitro and ex vivo heparin levels with aPTT test results in multiple individuals. In the absence of an established institutional therapeutic range, an aPTT ratio of 1.5-2.0 is commonly used; however, aPTT reagents and patient responses to unfractionated heparin vary, and the ratio can be 1.8-3.0 for some reagents.

The pharmacodynamics of LMWHs are different from the parent unfractionated heparin. LMWHs are administered subcutaneously. The aPTT test is not affected significantly by LMWH and is not used to monitor LMWH therapy. Several different LMWHs are available in the United States, but they have different pharmacodynamic properties and are not considered interchangeable. Weight-based dosing regimens for each LMWH and for treatment or prophylaxis indications are available from each manufacturer.

LMWHs are approved for treatment of deep venous thrombosis (DVT) with or without pulmonary embolism in the inpatient hospital setting. LMWHs are approved for treatment of DVT without pulmonary embolism in the outpatient setting.

Warfarin is used for long-term oral anticoagulant management of patients with protein S deficiency after first or subsequent thrombosis.


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