Pharmacology Flashcards
Which receptors do opioid analgesics act on?
Mu (u)
What is the codeine to morphine conversion?
240mg codeine = 30mg morphine (oral)
What are the contra-indications to Nitrous Oxide use?
- Air containing closed spaces eg pneumothorax, GI obstruction, post SCUBA dive
- RICP (as it increases cerebral blood flow)
How do aminoglycosides work and give an example
Gentamicin
Inhibit bacterial protein synthesis by binding to the 30S subunit
What are the contraindications to aminoglycoside (gentamicin) use?
Myasthenia Gravis
Use with caution in renal disease
What are the advantages of ketamine as an anaesthetic agent?
- Sympathetic effects (good for shocked patient)
- No effect on respiratory drive
- Bronchial smooth muscle relaxant (used in severe asthma)
What are the contraindications to ketamine as an anaesthetic agent?
RICP, stroke and head trauma
HTN
Severe cardiac disease
Acute porphyria’s
How do penicillin’s work?
Inhibit bacterial wall synthesis by preventing the crosslinking of peptidoglycan polymers
What is the main causes of resistance to penicillin’s? Which particular antibiotic is not affected by this mechanism?
Resistance is due to bacteria producing beta-lactamase
Flucloxacillin is resistant to the inactivation by beta-lactamase
What is the mechanism of action of digoxin?
Positive inotrope (contraction)
- inhibits NaKATPase
- increased intracellular Ca (NaCa exchange)
Negative chronotrope (rate)
- stimulate vagal activity
- ACh released
- slows rate, slows conduction, increases refractory period
When is digoxin contraindicated?
- WPW
- VT or VF
- 2nd or 3rd degree heart block
- HOCM
What can cause digoxin toxicity?
- Hypokalaemia
- Hypomagnesaemia
- Hypercalcaemia
- Hypoxia
How does warfarin affect PT and APTT?
PT grossly prolonged
APTT prolonged to a lesser degree
Describe the management of the following:
a) INR 5-8, no bleeding
b) INR 5-8, bleeding
INR 5-8, no bleeding: withhold 1-2 doses and restart at lower dose
INR 5-8, bleeding: IV vit K, restart when INR <5
Describe the management of the following:
a) INR >8, no bleeding
b) INR >8, bleeding
INR >8, no bleeding: Oral vit K, restart when INR<5
INR>8, bleeding: IV vit K, restart when INR<5
Describe the management of major bleeding in a warfarinised patient
IV vit K, Prothrombin complex concentrate
What are the P450 inducers?
- St John
- Phenytoin/ phenobarbitol
- Azathioprine
- Rifampacin
- Carbamezapine
What are the P450 inhibitors?
- Acute alcohol consumption
- Antibiotics
- Antidepressants
- Amiodarone
- Azoles
- Cranberry juice
- Corticosteroids
Beta-2 Agonists should be used with caution in people with….
- Arrythmias
- HTN
- QT prolongation
- Diabetes
- Hyperthyroidism
- Hypokalaemia
Normal saline contains what electrolytes?
154mmol/L Na
154mmol/L Cl
Hartmann’s contains what electrolytes?
(In mmol/L)
131 Na
111 Cl
29 HCO3
5 K
2 Ca
Describe the mechanism of action of unfractionated vs LMW heparin
UFH
- potentiates antithrombin III leading to inactivation of thrombin
- the heparin/antithrombin III complex also inhibits factor Xa
LMWH
- direct Xa inhibitor
What effect with heparin have on APTT and PT
Prolonged APTT
(and less so PT)
What is the antidote to heparin used in major haemorrhage?
Protamine sulphate
