Antiplatelet Therapies Flashcards
what are clinical indications for antiplatelet therapies?
to decrease risk of stroke, MI, vascular disease
what are the two most commonly used antiplatelets overall?
> Plavix (Clopidogrel)
> Aspirin (ASA)
name the most common P2Y12 receptor blocker antiplatelets
-Thienopyridines > Plavix (Clopidogrel) > Effient (Prasugrel) - Non-Thienopyridines: > Ticagrelor (Brilinta) > Cangrelor (Kengreal)
what is the MOA of ASA?
Irreversibly inhibits cyclooxygenase (COX-1) -> repeated dosing is necessary
aside from an antiplatelet therapy, what is aspirin also considered?
Salicylate acid
also: NSAID, antipyretic, anti-inflammatory
what is the therapeutic & maintenance/prophylaxis dose for ASA?
therapeutic: 75mc PO qd
maintenance: 81mg PO qd -»> preferred
what is the ASA dose after patients have a stroke or MI?
325mg PO QD
if a patient has an NSAID allergy, is it safe for them to take ASA and why?
no -> cross sensitivity: both drugs are grouped together
why are children NOT allowed to be given ASA? what is safe to give to them instead?
risk for developing Reye’s syndrome -> results in liver damage or swelling in the brain in kids
» safe to give Tylenol or Ibuprofen
in order to prevent GI Sx, what type of ASA should be given to patients?
enterocoated tablets -> prevents erosion of stomach lining
*also can provide Rx for PPIs or H2 blockers
most common sx of ASA?
N/V
GI bleed
ecchymosis (prolonged bleeding)
what PPIs are prescribed to prevent GI Side Effects of ASA?
• Omeprazole • Esomeprazole • Pantoprazole • Lansoprazol *** NOT PRN DRUGS -> QD dosing that must be tapered after 8 weeks
what are the adverse effects of PPIs? interactions?
adverse effects: > diarrhea > C. diff > hypomagnesemia overtime interactions > vitamin B12 > Plavix
what is PGE1 analog drug (non-PPI option) used to protect the stomach to prevent GI side effects of ASA & NSAIDs? what is it contraindicated in the use of?
Misoprotstol - Cytotec
-contraindicated in pregnant patients
what is the most commonly prescribed P2Y-12 ADP Receptor Blocker/Antagonist for antiplatelet therapy? what is its MOA?
Clopidogrel - Plavix
MOA- irreversible binding d/t to being a pro-drug that must be metabolized in the liver -> active metabolite
what is the dosage for Clopidogrel (Plavix) and what is it usually prescribed with fro dual platelet therapy?
75mg PO qd
-ASA
if a patient is undergoing surgery and is prescribed Clopidogrel (Plavix), how many days in advance must they hold it?>
at least 5 days prior to surgery
what are the adverse effects of Clopidogrel (Plavix)?
Bleeding
Steven Johnson Syndrome
TTP (Thrombocytopenia purpura)
what are drug interactions for Clopidogrel (Plavix)?
PPIs
> Omeprazole (Prilosec)
> Esomeprazole (Nexium)
if a patient with GERD is on Plavix what should they be prescribed? if they have a bleed, what should they be switched to?
Famotidine
> Switch to Pantoprazole (Protonix)
what P2Y-12 ADP Receptor Antagonist antiplatelet therapy has REVERSIBLE binding?
Ticagrelor (Brilinta)
what is a another P2Y-12 ADP Receptor Antagonist antiplatelet therapy has IRREVERSIBLE binding?
Prasugrel (Effient)
what antiplatelet therapy has a dual MOA of inhibiting platelet aggregation as well as being a coronary vasodilator?
Dipyridamole (Persantine)
what are side effects of Dipyridamole (Persantine) & what is a common food interaction?
side effects: dizziness, hypotension
food interaction: horse chestnut
what antiplatelet agent is a Phosphodiesterase inhibitor that is rarely used and inhibits the maturation of platelets?
Anagrelide (Agrylin)
what treatment is given to patients with Idiopathic Thrombocytopenic Purpura (ITP)?
high dose steroids or IVIG
what treatment is given to patients with Thrombotic Thrombocytopenic Purpura (TTP)?
plasmapheresis or exchange transfusion
what is the first line of tx for patients with ITP? what is the dosing and which requires a taper?
- Dexamethasone 40 mg po per day for 4 days with no taper
2. Prednisone po 1 mg/kg daily for one to two weeks followed by a gradual taper
what happens if a pt is not tapered off of Prednisone?
patients will experience side effects if not tapered because it is weight based
what is given to ITP patients if they cannot tolerate glucocorticoids?
IVIG within 24-48 hours
what is the first line tx for patients with Von Willebrand’s Disease & why?
Desmopressin (DDAVP) infusion because it works the fastest as an ADH replacement therapy
what is the MOA for Desmopressin (DDAVP)?
it is a synthetic analogue of antidiuretic hormone (ADH) that also increases factor VIII & vWF levels in plasma
what are the routes of administration available for Desmopressin?
subcutaneous
IV
intranasal
oral preparations
aside from ITP, what is Desmopressin also used for?
for peds patients that frequently wet the bed at night
what is important to monitor in dosing of Warfarin and why?
monitor labs (PT/INR) for incidence of clotting due to rapid decrease of protein C
what is the reversal for Warfarin and what routes of administration is it given by?
> Vitamin K PO (Mephyton)
> IM (Aquamephyton)
can vitamin K be given IV?
no -> will cause anaphylaxis
what drugs are given for Hyperfibrinolytic states?
Tranexamic Acid (TXA) Aminocaproic Acid (Amicar)
what is the MOA for TXA & Amicar?
Fibrinolysis inhibitors -> decreases plasmin formation and fibrinolysis
which fibrinolysis inhibitor is used more commonly and why?
TXA -> 10 times more potent than Amicar
what is a complication that can occur in heparin therapy? which is an immune reaction?
Type 1 & Type 2 Heparin-induced thrombocytopenia (HIT)
|»_space; Type 2 HIT: triggers formation of anti-heparin antibodies
what is the tx for HIT & when is it indicated?
Fondaparinex
> when pt on Heparin therapy has platelet levels < 50% of baseline
what are the main components of the plasmin (fibrinolysis) system responsible for natural anticoagulation within the body?
- Kallikrein
- Factors XIa and XIIa
- tissue plasminogen activator (tPA): most important, used to reduce thrombotic strokes
what is the most common fibrinolytic agent used in clinical settings? what are other recombinant forms of tPA?
- Alteplase (only tPA that is FDA approved): derived from human melanoma cells
- Tenecteplase
- Reteplase
which recombinant tPA has the longest half life and why?
Tenecteplase - greater binding affinity for fibrin than alteplase
what is the route of administration for tPA & what is its primary MOA?
IV only
> dissolves clots
when is tPA clinically indicated?
- Treatment of ST-segment elevation myocardial infarction (STEMI)
- Acute ischemic stroke (Alteplase only)
- Acute massive PE (Alteplase only)
- open clotted central venous access devices (Alteplase only)
what MUST be considered before administration of tPA for strokes?
TIME SENSITIVE
> must be given 3-4.5 hours from onset of stroke symptoms
what are pharmacologic & food interactions for tPA?
ASA, warfarin, anticoagulants, dipyridamole, heparin -> increase risk of bleeding
> horse chestnut
which fibrinolytic therapy is difficult to reverse & why?
Tenecteplase due to its long half life
what are clinical indications for tPA in thrombolytic therapy?
> extensive DVT > hypotension related to PE > severe hypoxemia > perfusion defect that is substantial > right ventricular dysfunction assoc w/ PE
what must be discontinued if a pt w/ acute venous thromboembolism is to start thrombolytic therapy?
heparin
what are absolute contraindications in the use of fibrinolytic therapy for acute DVT or PE?
- prior ICH -> including head contusion
- known structural cerebral vascular lesion
- malignant intracranial neoplasm
- ischemic stroke w/in 3 months
- aortic dissection
- active bleeding
- bleeding diathesis
- TBI or facial trauma w/in 3 months
what are relative contraindications in the use of fibrinolytic therapy for acute DVT or PE?
- trauma or surgery < 3 weeks
- pregnancy
- uncontrolled HTN -> SBP > 180 or DBP > 110
- recent internal bleeding
- pregnancy
- PUD
- current use of AC such as warfarin
- age > 75
- diabetic retinopathy
- pericarditis
what is the main difference between anticoagulants and thrombolytics?
anticoagulants are used for PREVENTION
thrombolytics re used for REMOVAL of clots already formed
what is an adverse rxn for Heparin?
excessive bleeding s/p small abrasions or minor trauma
-use of ASA
what is an adverse effect of Warfarin in regards to pregnant patients and why?
teratogenic -> can cross placental barrier & harm fetus including:
skeletal deformations
hemorrhagic disorders
what is a fatal complication for thrombolytics?
intracranial hemorrhage
what can NEVER be given with the use of thrombolytics?
heparin
what is the most common chemo induction therapy in tx for AML?
Cytarabine: antimetabolite
Daunorubicin: antitumor antibodies
in the treatment of AML, what is included in all chemo induction regimens?
Cytarabine
> added with antitumor antibody for collateral damage of good cells
what is the goal of chemo induction regimens for AML?
enable pt to get to remission and resolve hematologic effects
which leukemia is associated with the Philadelphia chromosome and what is considered a cause of this leukemia?
Chronic Myelogenous Leukemia (CML)
> high dose irradiation
what is the most commonly used preferred Tx for CML patients in REMISSION (in chronic phase)?
Imatinib (Gleevec)
> tyrosine kinase inhibitor that has the most long-term safety data
what is the route of administration for all tyrosine kinase inhibitors and dosing frequency?
oral - QD or BID
what enzyme does Imatinib (Gleevec) inhibit and what are the adverse effects?
CYP450 enzyme inhibitor
> Fluid retention, edema hepatotoxicity,
thrombocytopenia, or neutropenia
what is a PCP note that MUST be considered for patients with Acute Lymphocytic Leukemia (ALL)?
ALL patients cannot receive LIVE virus vaccines > varicella > zoster > MMR > nasal influenza
what is the preferred steroid tx for ALL patients?
Dexamethasone
potency is greater than prednisone
what is used for induction tx for patients with ALL?
Vincristine injections or infusions weekly
what are the adverse effects of Vincristine?
decreased creatinine clearance -> increased adverse drug effects
> permanent neurotoxicity, 8th cranial
nerve damage
what drugs are given in tx for Hodgkin lymphoma and what is the MOA?
1. Disruption of DNA function > Doxurubicin > Bleomycin 2. Disruption of DNA synthesis > Vinblastine > Dacarbazine
what drugs are given in tx for non-Hodgkin lymphoma?
Rituximab Cyclophosphamide Doxorubicin Vincristine Prednisone
