Pharmacology Flashcards
Patients on long term steroid therapy, due to to operation.
What to do with steroids?
If already receiving therapeutic dose (e.g. for COPD, asthma, rheumatoid arthritis)
—> Continue with the usual daily dose
If on physiologic replacement doses (e.g. for Addison’s disease)
—> Should receive additional 50mg of hydrocortisone intraoperatively
Contraindications to use nitrates
- SBP < 90mmHg
- HR < 50bpm or > 100 bpm
- Known right ventricular infarction
- Severe aortic stenosis
- Hypertrophic cardiomyopathy
Can lead to cardiac decompensation and haemodynamic instability
Sulphonylureas
Mechanism of action
- most wifely used drugs for T2DM
- gliclazide, glimepiride, glipizide
- stimulates pancreatic beta cells and causes secretion of insulin
- may also have extrapancreatic effects — increases tissue sensitivity to insulin (minimal effects though)
Best initial treatment of Parkinson’s disease
What to do when overstimulated?
Carbidopa/levodopa
- may develop dyskinesia after a few months
- due to overstimulation of dopamine receptors
- so must reduce the dose without loss of therapeutic efficacy
- alternative/can be added if cannot achieve: amantadine, pergolide
What antiepileptic drugs induces liver enzymes?
Side effects of these drugs on pregnant women?
What do to with women who are on antiepileptics and require OCPs?
Carbamazepine, phenytoin, barbiturates (phenobarbital), topiramates
High risk of teratogenicity: cleft lip or palate, cardiac anomalies, neural tube defects and hypospadias
RACGP: OCP with high estrogen content (Microgynon 50) should be used to minimise the risk of “pill failure”
If possible, ++ barrier method with condom.
[Not even progesterone-only pills should be used]
Gentamicin ~ botulism
Gentamicin
- prevents the release of acetylcholine from nerve endings like botulinum toxin
- can cause muscle paralysis in high risk patients
- if eliminate drug, symptoms subsides rapidly
- best avoided in those with pre-existing disturbance to neuromuscular transmission (myasthenia gravis)
Treatment for essential tremor
Propranolol or primidone
However, propranolol should be avoided in those contraindicated to BB (such as severe asthma)
If above fails benzodiazepines can be considered in low doses.
Under what circumstances can a patient continue to take hypnotics (such as temazepam or zolpidem etc) for more than 6 months or even years?
- Patient must be aware that they are dependent on that specific hypnotics
- No history of any adverse event/side effects from said medication
- Reduction program has been unsuccessful
If plan to stop, stop it gradually, not abruptly.
ECG of Digitalis Toxicity
- ST depression and T wave inversion in V5-V6 in reversed tick pattern
- Bradycardia
- Prolonged PR
- Shortened QT
- Arrhythmias, especially heart block or bigeminy
POP is not a reliable contraception in women taking enzyme-inducing antiepileptic drugs
There is one exception - which drug is it?
Sodium Valproate
Most prominent ECG abnormalities in tricyclic antidepressant (amitriptyline) overdose
- WIDENED QRS INTERVAL
Others:
- Prolonged PR and QT intervals
- VT/VF (4% of cases)
- Sinus tachycardia (anticholinergic effect and reflex tachycardia due to haemodynamic decompensation)
Most common cause of false positive elevation of plasma normetanephrine and norepinephrine level in those suspected to have phaeochromocytoma?
Tricyclic Antidepressants and Phenoxybenzamine
- 45% of the cases
- Fasting urinary metanephrines should be checked after stopping counfounding drugs
Other causes:
- Congestive cardiac failure
- Major depression
- Panic disorder
INR 5-9, no evidence of significant bleeding, what to do with warfarin?
Stop warfarin, give oral or IM vitamin K and check INR in 24H
If significant bleeding occurs before next blood taking, give urgent prothrombinex VF or FFP
INR 5-9
What constitutes clinically significant bleeding requiring immediate reversal of INR?
- intracranial bleeding
- retroperitoneum bleeding
- intraocular bleeding
- muscle bleed with compartment syndrome
- pericardial bleed
- active bleed with hypotension or 2g fall in haemoglobin
What PSY drugs are likely to cause alopecia or hair loss?
Lithium
Valproate
Carbamazepine
Phenytoin
How long it takes to see therapeutic effects of IV Vitamin K1 (Phytomenadione)?
6-8 Hours
Oral takes longer.
Combination of gabapentin and amoxicillin can cause…
Hepatotoxicity
Earliest sign of dose-related toxicity of carbamazepine
Diplopia, observed within 60 minutes after the morning dose
Donepezil
Contraindications
Donepezil
- anticholinesterase drug (decrease breakdown of acetylcholine)
- reduces apparent deficiency of cholinergic neurotransmitter activity in Alzheimer’s disease
- improves alertness and function, maintains cognitive scores for up to 12 months
- must do ECG TRO heart block of bradycardia before starting
Contraindications
- GI or ureteric obstruction
- active peptic ulcer
- heart block
- Bradyarrhythmias (including sick sinus syndrome)
- COPD
- Parkinson’s disease
Raloxifene
- Selective oestrogen receptor modulator (SERM)
- prevents postmenopausal bone loss
- reduces risk of vertebral fractures (not non-vertebral)
- reduces risk of breast CA
- hot flushes
- increases risk of DVT
Maximum dose is 60mg
If failed, do not combine with another osteoporosis treatment (not recommended)