Pharma/Tox Flashcards
Mechanism of action of bisphosphonates
Inhibits osteoclastic activity
Note: no effect on osteoblastic activity
Treatment of beta blocker overdose
1st line atropine
2nd line glucagon
Side effects of acetazolamide
MOA: inhibition of carbonic anhydrase
Metabolic acidosis (due to bicarb loss in the proximal and distal tubules, by inhibiting reabsorption)
HypoNa
Acute interstitial nephritis
Agranulocytosis and thrombocytopenia
Deafness is a recognised complication of aspirin overdose T/F
True
Management of aspirin overdose?
Gastric lavage up to 4 hours. Activated charcoal for sustained-release preperations
Plot level at 6 hours on normogram
Alkalisation of urine to aid drug excretion, close monitoring of electrolytes and pH , electrolyte repletion
In aspirin overdose hypoventilation is common T/F
False - tachypnea is common.
Note: Phase 1 tachypnea directly stimulates the resp center -> resp alkalosis with a compensatory alkaline urine with bicarb and potassium loss
Aspirin overdose is associated with hypoK and hyopglycaemia T/F
True
When is activated charcoal indicated in treatment of paracetamol OD?
If >150mg/kg taken + presentation <1 hr since ingestion
Melatonin is primarily metabolised in the kidney T/F
F - primarily met in the liver, hence can build up in those with hepatic impairment
The MOA of melatonin is due to binding to MT1 and MT2 receptors T/F
True
Note: MT1 is in the suprachiasmatic nucleus of the ant hypothalamus and MT2 is in the retina
Melatonin is C/I in those with epilepsy T/F
F - used to be thought to lower sz threshold but that was a poor study
Where is digoxin eliminated?
70% is excreted unchanged in the urine
NB: in patients with CKD they should be treated with a decreased loading dose and decreased maintenance dose
Patients on co trimoxazole need to be monitored for what serious (but rare) side effect?
Cholestatic jaundice
Code dose adrenaline?
0.1mg/kg 1:10,000
What is the most common adverse effect of theophylline overdose?
Arrhythmia (it is a phosphodiesterase inhibitor but also acts on adenosine receptors such as on the AV node)
Note: other adverse effects agitation, restlessness or seizure
What is the initial treatment of a TCA overdose?
IV sodium bicarbonate
Note: leads to QRS prolongation and possible tachyarhythmias due to Na channel blocking in the myocardium. Na bicarb increases TCA protein binding, dislodges TCA from the Na channel and increased TCA elimination. TCA OD renders the myocardium relatively insensitive to tradition antiarrhythmics.
What class of antidepressant is associated with GI bleeds?
SSRI
Doses in adrenaline pens for anaphylaxis?
EpiPen Jr 0.15mg (< 6yrs)
EpiPen 0.3mg (6-12 yrs)
IM adrenaline 0.5mg ( >12 yrs)
Indication for activated charcoal in drug overdose?
Within 1 hr of ingestion in a conscious patient (N +V are common post treatment so want to avoid in those with altered level of consciousness)
Trimethoprim can cause an elevation in urea and Cr T/F
F - only causes elevation in Cr. It completes with Cr for secretion into the renal tubules so causes asymptomatic elevation in serum Cr with no change in urea. This is not true renal injury
Where does cyclizine work?
Medulla oblongata
Beta blockers can cause difficulty sleeping/insomnia T/F
True
Can also cause hypoglycaemia
Side effect of prostaglandin
Apneoa
Treatment of hereditary angio-edema?
C1 inhibitor or kallikrein inhibitor ecallantide
Where does methylphenidate work?
Basal ganglia - inhibition of dopamine reuptake
Rifampicin reduces the levels of statin T/F
T
Clarithromycin increases the levels of statins
Antibiotic that increased the levels of statins?
Clarithromycin
Steroids are CI in the treatment of TB meningitis T/F
F - they are an adjunct to treatment with triple antiTB therapy
Mechanism of action of ipratropium bromide?
Anti muscarine bronchodilator
SE: mydriasis (dilated pupils), skin flushing, hyperthermia, dry skin and mouth, urinary retention and agitation
Usual stat tx dose of oral dex in croup tx?
0.15mg/kg
In patients with renal impairment the loading dose of drugs needs to be decreased T/F
F - loading doses remain unchanged - loading doses are related to the volume of distribution which remains unchanged.
Conversion of oral morphine to subcut diamorphine and subcut morphine?
10mg oral morphine = 3mg diamorphine
10mg oral morphine = 5mg subcut morphine
In the tx of allergic rhinitis when is an oral antihistamine 1st line (instead of intranasal)
Oral is first line if:
- pt 2-5 yrs
- preference to take oral
- conjunctivitis is also present
What is the MOA of baclofen?
Agonist of GABA beta receptor
What is the MOA of benzos?
Increase the potency of GABA at the GABA alpha receptors (AKA +ve allosteric modulator of GABA alpha receptor)
What medications should be avoid in those with Juvenile myoclonic epilepsy?
Carbamazepine
Phenytoin
Oxcarbazepine
They can aggravate the sz
Note: sleep deprivation and alcohol consumption can precipitate the sz; EEG will show periodic 3Hz spikes
What is considered a staggered dose of paracetamol? How does this impact treatment?
Staggered dose is any dose taken over longer than an hour. At greater than an hour the normogram cannot be used and hence if there is concern that a person has ingested a significant amount they should just be treated with NAC
What is the best steroid to use in a pt who already has HTN?
Dexamethasone - has little to no mineralocorticoid activity
Note: methylpred and pred have significant mineralocorticoid activity
What is a Type A drug reaction?
“Augmented” - eg hypotension with a beta blocker or hypoglycaemia with insulin
What is a Type B drug reaction?
“Bizarre” - anaphylaxis
What is a Type C drug reaction?
“Continued” - lasts for a long time, eg visual field defects with vigabatrin
What is a Type D drug reaction?
“Delayed” - eg neutropenia with chemo
What is a Type E drug reaction?
“End of use” - withdrawal symptoms
MOA of beta lactams?
Inhibition cell wall synthesis
Vancomycin also works in this way
MOA of colistin (a polymyxin)
Disrupts cell membrane integrity
MOA of co-trimoxazole ?
Inhibition of folate synthesis