Drug , anticoagulant action, mechanism

Compare and contrast the mechanisms of action of drugs used for ventricular rate control, conversion to sinus rhythm and maintenance of sinus rhythm in patients with AF, and explain the importance of anticoagulation for patients with AF. 

In the same way, the mechanism of action of drugs and coagulant and anticoagulant medication takes place through the variation of surface charge in the blood vessels. 

Ariens [432] was the first to describe drug action through indirect mechanisms. Later on, Nagashima et al. [433] introduced the indirect response concept to pharmacokinetic-dynamic modeling with their work on the kinetics of the anticoagulant effect of warfarin, which is controlled by the change in the prothrombin complex synthesis rate. Today, indirect-response modeling finds extensive... 

Cholestyramine interferes with the oral absorption of many drugs (including wrirfarin), resulting in decreased effectiveness. Aspirin and thyroid hormones enhance the action of warfarin via pharmacodynamic mechanisms. Increased anticoagulant effects with cimetidine or quini-dine result from the inhibition of metabolism of warfarin. The answer is (B). 

Gomez-Lechon MJ, Donato MT, Castell JV, Jover R (2003) Human hepatocytes as a tool for studying toxicity and drug metabolism. Curr Drug Metab 4 292-312 Hirsch J, Dahlen J, Anderson DR, Poller L, Bussey H, Ansell J, Deykin D (2001) Oral anticoagulants mechanism of action, clinical effectiveness, and optimal therapeutic range. Chest 119(Suppl) 8S-21S... 

The interaction between warfarin and benzbromarone or benziodarone is established and elinieally important. If benzbromarone is added to warfarin monitor prothrombin times and be alert for the need to reduce the dosage by about one-third to prevent over-anticoagulation. Information about other coumarins is limited, but what is known about the mechanism of action suggests that acenocoumarol and phenprocoumon would also be predicted to interact, and this has been shown for benziodarone and acenocoumarol or phenprocoumon, in a few patients. The limited evidence suggesting an interaction with some indanediones also suggests that some caution is appropriate with these drugs as well. 

Information appears to be limited to the reports cited here but the interaction would seem to be established and clinically important. Monitor the INR closely. A reduced warfarin dosage (the study cited above suggests a 30 to 60% reduction) is likely to be needed if both drugs are used concurrently to avoid excessive anticoagulation and possible bleeding. Note that bucolome is sometimes used with warfarin to enhance its therapeutic effect. Based on the mechanism of action, acenocoumarol and phenpro-coumon would be anticipated to be similarly affected. 

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