Drug reactions and interactions Flashcards
How are Adverse drug reactions investigated
ABCDE Augmented? - is reaction predicted Bizarre? -is there Hx of allergy Chronic? - Has Px used it for a long time Delayed? -Has Px used drug before End of use? - Has Px stopped drug use
Where should adverse drug reactions be reported to
MHRA Yellow card scheme
What patient factors affect drug interactions
Age
Polypharmacy
Genetics
Hepato/renal disease
What drug factors affect interaction
Narrow therapeutic index
Solubility
What is poly pharmacy
Use of Concurrent medication
What drug has a very narrow therapeutic index
Digoxin
-Slight overdose = bad news
What Pharmacokinetic influences affect drug action (ADME)
Admin - Affected by acidity, Motility and solubility
Distribution - Affected by protein binding
Metabolism
-CYP450 Induction = lowers therapeutic effect
-CYP450 Inhibition = Increase therapeutic effect
Excretion - affected by Urine pH
-Acid cleared fast in weak basic urine
-Base cleared fast in weak acidic urine
Whats the difference between CYP450 Induction and inhibition for drug metabolism
Induction = Lowers therapuetic effect (Alcohol) Inhibition = Increase therapeutic effect (Isoniazid and grape juice)
What three absorption influences affect drug interaction
Acidity
Motility
Solubility
What are naturally occurring Opiods
Morphine
Codeine
What are modified Opioids
Diamorphine (Heroin)
What is the oral bioavailability of Opiods
50%
Where are opiod receptors found and what are they targeted by
CNS
GIT
Pontine resp centers
Target of analgesia
What are the SE of opiod use
Addiction and depression
Constipation, N+V
Resp distress
What is meant by tolerance
Overstimulated opioid receptor causes desensitisation
What is meant by dependance
Craving euphoria
How is opiod induced resp depression treated
Naloxone
When is Naloxone used
Opioid causing resp depression
What are Antiplatelets
Aspirin and Clopidogrel
How does Aspirin work
Inhibit Cox1 so less Thromboxane 2 so less platelet activation
How does Clopidogrel work
Inhibit P2Y12
What are the main Anticoagulants
Heparin
Warfarin
DOACs
Thrombolysis
How does Heparin work
Activate antithrombin 3 and inhibit factor X
How does warfarin work
Inhibits Vit K epoxide reductase
How do DOACs work
Anti Factor Xa
What are some examples of DOACs
Rivoroxaban
Apixaban
How does Alteplase thrombolysis work
Activate plasmin to degrade fibrin = less coagulation
How do NSAIDs work
Inhibit Cox 1+2 = prevent prostaglandin production
Cox1 inhibition = less gastric mucosal protection, Raised Gastric acid = GI ulcers
Cox 2 inhibition = Anti inflammatory
How do NSAIDs cause GI Ulcers
Inhibit Cox 1
Less gastric mucosal protection
Gasric acid wears away lining
GI Ulcers
What is a SE of NSAIDs
Peptic ulcer disease
What is a SE for ACE-i
bradykinin increase = dry cough
Afferent arteriole dilation = low GFR = AKI
hyperkalemia
What is a SE of PPI
Increase fracture risk
What is a SE of Opioids
Resp distress (Give naloxone)
Tolerance and dependance and addiction
N+V and Constipation
What is the SE of loop diuretic and thiazides
Hypokalemia
What is the SE of Spiranolactone
Hyperkalemia because potassium sparring
How do loop diuretics work
Inhibit NKCC2 in ascending Loop of Henle
NA, K, CL and water excretion
How do thiazides work
Inhibit NaCl in DCT
NaCl and water excretion
How does spironolactone work
Inhibit ENaC Channel = aldosterone antagonist
Na and water excretion w/ K retention
