Pharmacology Flashcards
DMARDs that can be used in pregnancy
Azathioprine
Sulfasalazine
B-blocker association
Myasethenia Gravis
- They act on the neuromuscular junction
Progesterone in HRT
Associated Risks
Breast cancer
Increased risk of VTE
Risk of Methadone
QT prolongation and sudden cardiac death
What type of receptors do steroids act on?
Nuclear receptors
What type of receptors do hormones (largely) act on?
Nuclear receptors
Why do you need a loading dose of amiodarone?
When should it be avoided?
Slow metabolism - long half life and very lipophillic
Because very lipid soluble, storied in body tissues
Avoid in breast feeding
Levothyroxine absorption
- what medications affect absorption?
- how managed?
Iron/calcium
Take at least 4 hours apart
Mechanism of action of baclofen
GABA agonist
TB medication associated with gout
- why?
Pyrazinamide
- Causes hyperuricaemia = gout
Class I anti-arrhythmics
- examples
- phase of cardiac action potential
1b = lidocaine, phenytoin
1c = fleccanide
Phase = 0 (block sodium channels)
Class II anti-arrhythmics
- examples
- phase of cardiac action potential
Beta blockers
Phase = 4 - acts on K+ rectifier current
Class III anti-arrhythmics
- examples
- phase of cardiac action potential
Amiodarone, sotalol
Phase = 3 - K+ channel blocker
Class IV anti-arrhythmics
- examples
- phase of cardiac action potential
Verapamil, diltiazem
Phase = 2, calcium channel blockers
What not to use with PDE5 inhibitors?
Nitrates
Can cause severe hypotension
Zero order kinetics =
= amount of drug excreted is constant, regardless of plasma concentration
Which part of hyperkalaemia treatment encourages excretion of K+ out of the body?
Calcium resonium
Side effect of nicorandil?
GI ulceration - can be ++ severe
Best non-sedating anti-histamine
Loratadine
Safe for LORRY drivers
Side effect of trimethoprim
Pancytopaenia
Mechanism of action of cyclophosphamide
Promotes cross linking in DNA
What is the mechanism of carvedilol?
Non selective B blocker/alpha adrenoceptor antagonist
TCA overdose - is dialysis involved in management?
Not usual part of management - large volume of distribution
Threshold for LFTs + statin and stopping the statin
If transaminases rise and persist @ 3x upper limit of normal
INR + dental work
Check 72 hours before
If <4 then can proceed
Mechanism of action of sulphonylureas
Close K+/ATP channel on B cells in the pancrease
= depolarisation then calcium exocytosis = release of insulin
What precipitates the effects of digoxin? (5)
Hypokalaemia - binds to the ATPase pump/competes with K+
Less K+ = more of an effect
Increasing age
Renal failure
Hypercalcaemia
Hypomagnesaemia
Give a sulphonylurea
Give an effect
Chlorpropramide
SIADH
Effect of MDMA
Hyponatraemia
Contraindication to triptan use
Ischaemic heart disease
- can cause coronary artery vasospasm
Management of early presentation salicylate toxicity
Charcol can be given if within 1 hour of ingestion
How can a steady state be reached quicker?
Loading dose
Increased frequency of dosing
Examples of medications metabolised on first pass metabolism (5)
(liver)
Propranolol
Oestrogens
Verapamil
(intestinal mucosa)
Levodopa
Ethanol
Examples of drugs that exhibit zero order kinetics (3, exception)
Phenytoin
Heparin
Ethanol
Salicylates - at high doses
Drugs which decrease absorption (3)
Iron
Cholestyramine
Anti-cholinergics
What occurs in phase I reactions?
Oxidation/reduction/hydrolysis
What occurs in phase II reactions?
Conjugation
Drugs dependent on acetylator status (4)
Dapsone
Hydralazine
Isoniazid
Sulfalazine
What are CYP450? What are they involved with?
= group of enzymes involved in drug reactions: specifically phase I metabolism
What does a CYP450 inducer do?
= increased CYP450 expression
= increases metabolism of the drug
= reduced therapeutic concentrations
Inducer - reduce the effectiveness of the drug e.g. reduce contraceptive efficacy
What does a CYP450 inhibitor do?
= decreased CYP450 expression
= decreased metabolism of the drug
= elevated therapeutic concentrations: TOXICITY
Examples of CYP450 inhibitors
3A 2S RIF
3A - antibiotics (cipro/erythromycin), allopurinol, amiodarone
2S - SSRIs, sodium valproate
R - ritonavir
I - isoniazid
F - fluconazole
Which antibiotics are CYP450 inhibitors?
Ciprofloxacin
Erythromycin
Examples of CYP450 inducers
RAS
R - rifampicin
A - anti-convulsants
Phenytoin, carbamazepine, phenobarbitone
S - steroids
Dexamethasone, prednisolone
Which antibiotics are CYP450 inducers?
Rifampicin
What is the effect of alcohol on the CYP450 enzyme system?
Acute alcohol intake = enzyme inhibitor (decreased metabolism, more toxic effects)
Chronic alcohol intake = enzyme inducer
(increased metabolism, reduced therapeutic concentrations)
Metabolism of alcohol
Ethanol to acetaldehyde (requires alcohol dehydrogenase)
Effect of verapamil
Side effects
Compared to diltiazem
= negative inotrope
(contra-indicated in HF, not to use in conjunction with BB)
S/E: constipation, bradycardia
Diltiazem less negatively inotropic
Adverse effect of dihydropyridine CCBs
Reflex tachycardia
(relax vascular smooth muscle, increased HR to maintain CO)
Medications to avoid in G6PD deficiency (4)
Sulphonamides
Nitrofurantoin
Ciprofloxacin
Primaquine
Amiodarone is a…
CYP450 inhibitor
= increased risk of toxicity e.g. digoxin or warfarin toxicity
What medication is good for lowering triglycerides?
Fibrates
Interactions with levodopa (4)
Effect
MAO-I
Methyldopa
Haloperidol
Metoclopramide
= decreased levodopa effect
Side effects of isoniazid (3)
Peripheral neuropathy
Pellagra
Agranulocytosis
Side effects of Ethambutol (2)
Colour vision defects
Retrobulbar neuritis
Side effect of Rifampicin (3)
Nephritis
Thrombocytopaenia
Urine colour changes
Side effect of Pryazinamide
Hyperuricaemia
Management of heparin overdose/heparin reversal
Protamine
Drugs to avoid in breast feeding (5)
Aminoglycosides
Tetracyclines
Isoniazid
Phenytoin
Carbimazole
Management of methanol poisoining
Fomepizole
(previously was ethanol)
Severe - haemodialysis
Management of salicylate poisoning
Activated charcoal if <1 hour since ingestion
IV bicarbonate
HD in severe cases
Management of ethylene glycol poisoning
- mechanism
Fomepizole
= competitive inhibition of alcohol dehydrogenase
What to avoid in arrhythmia in TCA overdose
Class Ia/c - prolong depolarisation
Class III - prolong QT
Management of mild/moderate lithium poisoning
Volume resuscitation
Management of iron poisoning
Desferrioxamine
Management of cyanide poisoning
Hydroxycobalamin
Action of alpha-1 receptor
- mechanism
- agonist
- antagonist
= vasoconstrictor, GI smooth muscle relaxation, salivary secretion
Activates phospholipase C
Agonist = phenylnephrine
Antagonist = doxazosin, tamsulosin
Action of alpha-2 receptor
- mechanism
- agonist
= inhibits neurotransmitter (pre-synaptic)
Acts to inhibit adenyl cyclase
Agonist = clonidine, brimonidine
Action of beta-1 receptor
- mechanism
- agonist
- antagonist
= positive inotrope and chronotrope: acts on cardiac tissue
Stimulates adenyl cyclase
Agonist = dobutamine
Antagonist = atenolol
Action of beta-2 receptor
- mechanism of action
- agonist
- antagonist
= vasodilation and bronchoconstriction, relaxation of GI smooth muscle
Stimulates adenyl cyclase
Agonist = salbutamol
Mechanism of action of ketamine
NMDA antagonist
Ethylene glycol poisoning
- biochemical finding
- management
Raised anion gap metabolic acidosis
Mx: fomepizole
What is nabilone?
Synthetic cannabinoid
Side effect from ACE-I initiation
First dose hypotension
Electrolyte abnormality associated with loop diuretics
Hypomagnesaemia
(think hypokalaemia, magnesium and potassium are friends)
Glargine insulin VS isophane insulin advantage
Better at avoiding nocturnal hypoglycaemia
Mechanism of action of gabapentin
Binds to A2 subunit of calcium channel
