Prostaglandins Flashcards
What has been identified as the main prostaglandin that causes redness, swelling, & pain?
PGE2
What is the treatment for open angle glaucoma and eyelash hypertrichosis?
Latanoprost
- darkens and elongates eyelashes
COX1 vs COX2 which are always present in the blood?
COX1 are always present - help maintain gastric lining
COX2 are induced & just appear
What is COX2 important for?
Synthesizing the prostaglandin mediators of PAIN, INFLAMMATION, & FEVER.
- almost all COX2 inhibitors have been taken off the market d/t cardiovascular risk
- except Celecoxib (Celebrex)
True or False: Aspirin and NSAIDs both inhibit COX enzymes.
True
Is Aspirin competitive or non-competitive inhibitor of platelet function?
Aspirin is a non-competitive inhibitor = irreversible inhibitor of platelet function = the effects lasts for the lifetime of the platelet (8-12 days)
Are NSAIDs competitive or non-competitive antagonists of COX1 & COX2?
NSAIDs are competitive antagonists
- their effect only lasts as long as the drug’s time to elimination
True or False: Naproxen & ibuprofen are selective COX inhibitors.
False: NON-selective
Relative contraindications for Ketorolac: (4)
Ketorolac (Toradol) is an NSAID
- Asthma
- Renal dysfunction
- GI dysfunction
- Bleeding disorders
What is the dose of IM Ketorolac for patients older than 65 yo, renal impairment, & or less than 50 kg
Just give one dose of 30 mg IM
What is the IV dose of Ketorolac for patients younger than 65 yo?
What about over 65 yo, < 50 kg
< 65 you = 30 mg dose
> 65 yo & < 50 kg = 15 mg
What is the maximal dose of Ketorolac?
If giving a multiple dose treatment of IV or SubQ & pts > 65 = 30 mg q 6 hrs
NEVER exceed 120 mg per day
True or False: Aspirin is a selective inhibitor of COX1
False: Aspirin (NSAID & anti-platelet) inhibits COX1 & COX2
BUT favors COX1
What medication is also known as an arachidonic inhibitor?
Aspirin
Which NSAID should you take on a full stomach to reduce stomach irritation?
Aspirin
True or False: Ibuprofen inhibits both COX1 & COX2
True.
Similar inflammatory response as aspirin
Which COX does Acetaminophen inhibit?
Inhibits COX3.
Not a complete COX1 or COX2 inhibitor but somewhere in between because it is not a good inflammation reducer.
Cleecoxib (Celebrex) inhibits which COX?
COX2 specific inhibitor
- good anti-inflammatory, analgesic, & antipyretic
When is Celecoxib (Celebrex) most commonly used?
Used for RA
- good anti-inflammatory, analgesic, antipyretic
- reduce prostaglandins in synovial fluid
- increases platelet aggregation (clotting) so increases myocardial infarction & stroke
What is the most commonly prescribed Adenosine diphosphate receptor inhibitor?
Clopidrogel (Plavix)
Plavix works by binding ___________ to inhibit the expression of GPIIb/IIIa on the surface of the platelet thus inhibiting platelet adhesion & aggregation.
Non-competitive & irreversible antagonist.
What is the goal of adenosine diphosphate receptor inhibitors?
To inhibit thromboembolism
GPIIb/IIIa inhibitor abcixmab (ReoPro) has a half-life of ?
24-48 hrs
- longest acting
(Aggrastat) Tirofiban = 20-40 min
(Integralin) eptifibatide = 20-40 min
Vitamin K antagonists inhibit synthesis of Vit K dependent clotting factors including:
II, VII, IX, & X
How are Vit K antagonists metabolized?
CYP 450
Vit K antagonists onset & half life?
Warfarin competes with Vit K for binding sites
- Onset 72-96 hrs (requires heparin bridging)
- Half-life 36-42 hrs
What factors are inhibited by heparin?
Are they intrinsic or extrinsic?
Thrombin IIa and factor Xa by binding to AT (anti-thrombin), IX, XI, XII
- influences both intrinsic & common pathways
Which test are used to monitor Heparin?
aPTT & ACT
What is the reversal for Heparin?
Protamine
What is the main complication of Heparin?
Thrombocytopenia
What is a low molecular weight Heparin and what does it inhibit?
(LMWH) Lovenox
- Fractionated form of heparin w/ more specific inhibition of Xa
What is the most important anticoagulant in the blood?
Antithrombin (AT)
- formally known as antithrombin III
Antithrombin (AT) inhibits thrombin activity and disrupts clot formation via:
Binds factors II and X most strongly
- with less strength to factors IX, XI, XII
How can you increase the inhibitory effect of antithrombin
The inhibitory effect of antithrombin is increased 1,000 fold by heparin
Protamine comes from salmon sperm there fore what should you do before giving?
Give a test dose to check for anaphylaxis (usually 10 mg)
How should you administer Protamine?
Slowly administer over 10-15 minutes to avoid hypotension
What are the complications related to Protamine administration? (5)
- Too rapid of administration (histamine release)
- Overdose
- Repeated doses
- Repeated administration
- Current or previous use of protamine
Indirect Factor Xa antagonists
(Arixtra) Fondaparinux - free factor Xa binds w/ AT
How soon should you discontinue your indirect factor Xa antagonist?
Discontinue for elective minor surgery 48 hours ahead of time & longer before major surgeries (eye, spine, brain, or renal disease)
What are the 3 Direct Factor Xa antagonists and when should you D/c them ?
(Xarelto) Rivaroxaban, (Eliquis) Apixaban, (Savaysa) Edoxaban
- D/c 24 hrs in advance, 48 hrs ahead of major surgery (eye, spine, brain, or renal disease)
What are the 2 Antifibrinolytics and which is more potent?
Amicar & TXA
- TxA is 5x’s more potent than Amicar
What is the dose for TxA
Trauma dose 10-15 mg/kg followed by 1-5 mg/hr infusion
What are considered competitive antagonists at the parietal H2 receptors, used to suppress gastric acid secretion?
H2 Blockers or Histamine antagonist
- Famotidine (Pepcid, Zantac)
- Cimetidine (Tagamet)
- Nizatidine (Axid AR)
What does histamine do after released?
It boosts blood flow to the area of the body where the allergen is, it will cause inflammation & let other chemicals in
Which histamines cross the BBB?
H1 antagonist
- cause drowsiness
- helps with motion sickness
