2942342
Description
Flashcards by jenny schneider, updated more than 1 year ago
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Created by jenny schneider
almost 9 years ago
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| Question | Answer |
| Which of the following is an injectable Factor Xa inhibitor? dabigatran warfarin rivaroxaban fondaparinux | rivaroxaban is a factor Xa inhibitor but is oral; fondaparinux is injectable factor Xa inhibitor |
| True or False Fondaparinux is obtained from animal sources | False; it is synthetic compound and hence cannot transmit animal pathogens |
| True or False Fondaparinux contains the specific five saccharide sequence that is found in UFH | True |
| Fondaparinux is not metabolised in the liver and is renally eliminated | True |
| True or False: The anticoagulant effect of fondaparinux can be reversed by protamine | False the effect is not reversed by protamine and in the case of a major bleed, fresh frozen plasma and factor concentrates should be administered |
| which of the following is oral factor Xa inhibitor? enoxaparin lepirudin rivaroxaban | rivaroxaban |
| True or False: rivaroxaban has relative bioavailability of 80% and is 2/3 eliminated renally | true |
| which of the following is not a direct thrombin inhibitors? enoxaparin warfarin hirudin bivalirudin lepirudin | enoxaparin, warfarin are not direct thrombin inhibitors |
| where did hirudin first come from? | isolated from saliva of leech |
| what is hirudin composed of? | 65 amino acids |
| how is lepirudin made? | lepirudin is 65 amino acid sequence- it is made by recombinant technology (same sequence as Hirudin) |
| How does bivalirudin differ from lepirudin? | Bivalirudin is a synthetic a 20 amino acid resides. It has a shorter half-life than lepirudin. Bivalirudin, unlike lepirudin, is a reversible inhibitor of thrombin as thrombin can cleave bivalirudin and the two fragments formed have little affinity for thrombin |
| what is an example of an oral direct thrombin inhibitor? | dabigatran |
| True or False: Dabigatran is a univalent DTI (binds only to one site) while bivalirudin and hirudin bind to two sites on thrombin | True |
| Explain why dabigatran is administered as dabigatran etexilate | this is a prodrug which increases the bioavailability. The prodrug is converted to the dabigatran by esterases in the gut, liver and plasma |
| what is the dominant pathway for eliminaiton of dabigatran? | renal elimination (up to 80% excreted unchanged) |
| Explain the design of Pradaxa capsules | Capsule shell containing pellets about 1mm in diameter. Pellets are tartaric acid with prodrug coated onto them. The presence of the tartaric acid reduces variability of dabigatran etexilate absorption which depends on an acid environment |
| why should pellets not be removed from pradaxa capsules and administered this way? | capsules should not be broken, chewed or opened before administration as there is a 1.8 fold increase in bioavailability when this is done- this increase in bioavailability may lead to too much anticoagulant effect in patient |
| what are advantages of dabigatran orally compared to warfarin orally | rapid onset of action (no need for bridging) predictable anticoagulant effect (no need for routine monitoring) targets specific enzyme low potential for food interactions low potential for drug interactions |
| what are some disadvantages of dabigatran compared to warfarin | warfarin has been used for many decades, so working with this is better known (lots of exeperienc with this drug) while dabigatran is relatively new INR monitoring is well established way of monitoring warfarin while if you have to monitor dabigatran, uncertain what to monitor warfarin is mainly cleared hepatically while dabigatran is mainly renal (not use in renal dysfunction) we can reverse adverse effect of warfarin with Vitamin K but we have no drug that we can administer to reverse effect of dabigatran at this stage |
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