Understanding antiplatelet drugs on the USMLE Step 1 exam

Tyler York
antiplatelets

Another high yield USMLE Step 1 pharmacology topic is antiplatelet drugs. This video provides an overview of the pharmacology of cardiovascular drugs, with a focus on antiplatelet drugs. It covers the mechanism of action of aspirin, and other antiplatelet drugs. The adverse effects of aspirin are also discussed.

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Full Antiplatelet Drugs video transcript:

00:00
 anti-platelet drugs are a very important
 00:02
 concept for the usmle step one
 00:04
 do you know their mechanism of action
 00:06
 are you familiar with their important
 00:08
 side effects
 00:09
 let's take a look let's begin with a few
 00:12
 important concepts regarding platelets
 00:14
 platelets are formed from megakaryocytes
 00:17
 and they have a lifespan of around 8 to
 00:19
 10 days
 00:20
 platelets have two important storage
 00:22
 granules alpha granules
 00:24
 and dense granules alpha granules are
 00:27
 more
 00:27
 numerous they store fibrinogen one will
 00:31
 bring factor
 00:32
 and glycoprotein 2b3a dense granules
 00:36
 release their contents when platelets
 00:38
 are aggregated
 00:39
 and their contents aid in platelet
 00:42
 aggregation
 00:43
 dense granules store adp
 00:46
 atp catecholamines serotonin and calcium
 00:50
 glycoprotein 2b3a acts as a receptor for
 00:54
 fibrinogen
 00:55
 on the surface of platelets antiplatelet
 00:59
 drugs are divided into four different
 01:01
 classes
 01:02
 cyclooxygenase inhibitors adp inhibitors
 01:06
 glycoprotein 2b3a inhibitors and
 01:09
 phosphodiesterase inhibitors
 01:11
 let's begin with cyclooxygenase
 01:13
 inhibitors this class includes
 01:15
 aspirin and triflusal aspirin
 01:18
 is an irreversible inhibitor of the
 01:20
 enzyme coxone
 01:22
 or prostaglandin8 synthase it inhibits
 01:25
 the synthesis of thromboxane
 01:27
 a2 thereby inhibits platelet aggregation
 01:31
 common side effects of aspirin include
 01:34
 nausea
 01:35
 heartburn slightly increased risk of
 01:38
 intracranial hemorrhage
 01:39
 and abdominal or epigastric pain
 01:42
 if you give enterocoated aspirin the
 01:45
 abdominal
 01:46
 or gi side effects of aspirin can be
 01:49
 decreased
 01:50
 however since it is an irreversible
 01:52
 inhibitor the action of aspirin
 01:55
 will last the whole lifespan of the
 01:58
 platelet which is eight to ten days
 02:01
 adp inhibitors include clopidogel or
 02:04
 plavix
 02:05
 pressure gel ticagrelor anticlopidine
 02:09
 all these clopidogel and presudrail are
 02:11
 pro drugs
 02:12
 which need to be activated by cytochrome
 02:14
 p450 system in the liver
 02:16
 they are given as adjuncts to aspirin
 02:20
 in patients undergoing percutaneous
 02:23
 coronary intervention
 02:24
 or angioplasty with stent placement
 02:28
 common side effects include diarrhea and
 02:30
 skin rash with clopidogel and procedure
 02:33
 t-copeline may cause neutropenia
 02:35
 thrombocytopenia
 02:36
 and ttp or thrombotic thrombocytopenic
 02:39
 purpura
 02:41
 the next class of antiplatelet drugs is
 02:43
 glycoprotein 2b3a inhibitors
 02:46
 they include abscisimam terophiben
 02:49
 and eptiphepatite of these abscessimap
 02:52
 is a monoclonal antibody that binds to
 02:54
 the glycoprotein 2b3a receptor
 02:57
 whereas sterophyben and eptifibertide
 03:00
 they mimic
 03:00
 part of the structure of fibrinogen and
 03:03
 compete with fibrinogen
 03:05
 on binding to the glycoprotein 2b3a
 03:09
 receptor
 03:10
 side effects include thrombocytopenia
 03:12
 glycoprotein 2b3a inhibitors are given
 03:15
 in patients who are undergoing
 03:16
 percutaneous coronary interventions like
 03:18
 angioplasty with stent placement the
 03:21
 last class of anti-platelet drugs
 03:24
 is phosphodiesterase inhibitors these
 03:26
 drugs in
 03:27
 erase the camp levels within the
 03:29
 platelets and
 03:30
 include dipyridamole and cilostazol
 03:33
 silostazole is metabolized by cytochrome
 03:36
 p450 enzyme system
 03:38
 in the liver hence its dose needs to be
 03:41
 decreased
 03:41
 in patients who are concomitantly being
 03:44
 treated with cytochrome p450 inhibitors
 03:47
 like omeprazole
 03:48
 so let's recap the important points
 03:51
 there are four classes of antiplatelet
 03:53
 drugs
 03:54
 cyclooxygenase inhibitors adp inhibitors
 03:57
 glycoprotein 2b inhibitors and
 04:00
 phosphodiesterase inhibitors
 04:03
 aspirin is an irreversible inhibitor of
 04:05
 the enzyme cox 1
 04:07
 or prostaglandin h synthase aspirin is
 04:10
 given along with copyright gel in
 04:11
 patients undergoing percutaneous
 04:13
 coronary
 04:14
 interventions the glycoprotein 2b3a
 04:17
 inhibitors include abscissimam
 04:19
 eptiphypatite anterophyben ticlopidine
 04:23
 is associated with ttp or thrombotic
 04:26
 thrombocytopenic purpura
 04:28
 phosphodiester is inhibitors raise
 04:31
 intraplatelet
 04:32
 camp levels thanks for watching
 04:35
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