Anticoagulant effect

The pharmacological and/or adverse effects of a drug can be reversed by co-administration of drugs which compete for the same receptor. For example, an opioid receptor antagonist naloxone is used to reverse the effects of opiates. Drugs acting at the same site with opposite effects also can affect each other, e.g. the reduction in the anticoagulant effect of warfarin by vitamin K. 

The HMG-CoA reductase inhibitors have an additive effect when used with the bile acid sequestrants, which may provide an added benefit in treating hypercholesterolemia that does not respond to a single-drug regimen. There is an increased risk of myopathy (disorders of the striated muscle) when the HMG-CoA reductase inhibitors are administered with erythromycin, niacin, or cyclosporin a When the HMG-CoA reductase inhibitors are administered with oral anticoagulants, there is an increased anticoagulant effect. 

When the anabolic steroids are administered with anticoagulants the anticoagulant effect maybe increased. Administration of methyitestosterone with imipramine may cause a paranoid response in some patients The anabolic steroids may increase the hypoglycemic action when administered with thesulfonylureas... 

The administration of cloflbrate to a patient taking warfarin will potentiate the anticoagulant effect of warfarin by displacing It from Its protein binding site (7). This Interaction will cause... 

Warfarin exerts its anticoagulant effect by inhibiting the production of the vitamin K-dependent coagulation factors... 

Increased Anticoagulation Effect Decreased Anticoagulation (Increase Bleeding Risk or T INR) Effect (4- INR)... 

Prothrombin time PT is performed by adding thromboplastin (tissue) factor and calcium to citrate-anticoagulated plasma, recalcifying the plasma, and measuring the clotting time. The major utility of PT is to measure the activity of the vitamin K-dependent factors II, VII, and X. The PT is used in evaluation of liver disease, to monitor warfarin anticoagulant effect, and to assess vitamin K deficiency. 

Barzu T, Level M, Petitou M, Lormeau J-C, J. Choay J, Schols D, Baba M, Pauwels R, Witvrouw M, De Clercq E. Preparation and anti-HIV activity of O-acylated heparin and dermatan sulfate derivatives with low anticoagulant effect. J Med Chem 1993 36 3546-3555. 

Food intake Increase of alimentary vitamin K1 intake, resulting in decreased anticoagulant effect... 

The answer is d. (Hardman, p 1346.) A slow intravenous infusion of protamine sulfate will quickly reverse the bleeding. Protamine binds to heparin to form a stable complex with no anticoagulant activity It may also have its own anticoagulant effect by binding with platelets and fibrinogen. 

Hirudin exhibits its anticoagulant effect by tightly binding thrombin, thus inactivating it. In addition to its critical role in the production of a fibrin clot, thrombin displays several other (non-enzymatic) biological activities important in sustaining haemostasis. These include ... 

The anticoagulant effect of UFH is mediated through a specific pentasaccharide sequence on the heparin molecule that binds to antithrombin, provoking a conformational change. The UFH-antithrombin complex is 100 to 1,000 times more potent as an anticoagulant than antithrombin alone. 

Like UFH, the LMWHs enhance and accelerate the activity of antithrombin and prevent the growth and propagation of formed thrombi. The peak anticoagulant effect is seen in 3 to 5 hours after SC dosing. 

The preseuce of heparin on their surface which exerts an anticoagulant effect. 

When administered concomitantly, clarithromycin and the oral anticoagulant warfarin may interact, resulting in an enhanced anticoagulant effect and therefore increased risk of bleeding. 

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