ACC Cardiac/ arrythmia drugs Flashcards
Clinical indications for O2? x3
- Hypoxaemia
- PTX: To accelerate resorption of pleural gas
- CO poisoning: to reduce half life of carboxyhaemoglobin
O2 MOA?
Increases the PO2 in alveolar gas.
In PTX: it reduces the fraction of nitrogen in alveolar gas
In CO poisoning, it competes with CO to bind with hb and shortens half life of carboxyhaemoglobin
O2 side effects/ warnings?
Lack of water vapour: dry throat
In T2RF/ COPD pts it results in high CO2 concentration causing resp acidosis, depressed consciousness and worsened tissue hypoxia
O2 Doses?
Acute setting: 15L/ min via non-rebreathe mask (60-80%)
28% for T2RF patients
Nasal cannulae (24-50%) flow rate 1-4L/min)
Nitrates clinical indication? X3
Short acting (GTN): Acute angina and ACS Long acting (Isosorbide mononitrate): angina prophylaxis where Bblockers and or CCB don't work IV nitrates: Pulmonary oedema- used in combo with furosemide and O2
Nitrates MOA?
Nitrates elimination?
Nitrates are converted to NO
NO increases cGMP synthesis and reduces intracellular Ca2+ in SM cells= relaxation
This causes venous and a little arterial vasodilation
This reduces cardiac work and myocardial O2 demand relieving angina and cardiac failure
Eliminated by liver and partly passed unchanged in the urine
SE of nitrates?
Headaches/ lightheadedness
Flushing
Hypotension
Sustained use= tolerance
Cautions/ contraindications of Nitrates
CI: severe AS pts= cv collapse bc the heart can’t increase CO sufficiently to maintain pressure in dilated vasculature
CI: Pts with haemodynamic instability and HTN
Nitrates interactions
Phosphodiesterase inhibitors e.g. sildenafil: enhance and prolong hypertensive effect of nitrates
Caution in pts already taking hypertensive medication= precipitate hypotension
GTN and Isosorbide dose?
Spray GTN for angina prophylaxis: 400-800mg under tongue prn
Spray GTN for angina treatment: 400-800mg under tongue- 5 min intervals- after 3 seek medical attention
IV GTN= solution containing 50mg in 50ml= 1mg/ml
ISMN: angina prophylaxis and adjunct in CHF = 20mg BID-TID, increase if necessary to 120mg in divided daily dose
How would you explain to the pt what the nitrates are for?
This medication is being prescribed to help you with your chest pain and or breathless.
You might develop a headache but this usually doesn’t last for long.
We normally advise patients to use GTN before an activity that might bring on your angina
As your BP can drop, it’s a good idea to sit down and rest for about 5 mins while taking them
How do you monitor nitrate efficacy?
Do symptoms resolve
When using IV infusion measure blood pressure frequently
Aspirin drug class and clinical indications x 3
Salicylates
ACS/ Acute Ischaemic stroke: rapid inhibition of platelet aggregation
Long term secondary prevention of thrombotic arterial events in patients with CV, cerebrovascular and PAD
To reduce risk of intracardiac thrombus and embolic stroke in AF
Aspirin MOA?
Aspirin elimination?
Irreversibly inhibits COX to reduce production of arachidonic acid
This reduces platelets aggregation and the risk of arterial occlusion
Antiplatelet effects of aspirin occur at low doses and last for a lifetime
Elimination: Effects of aspirin last for the lifetime of the platelet, urinated out
SE aspirin?
Gastrointestinal irritation
GI ulceration and haemorrhage
Hypersensitivity reactions= bronchospasm
Regular high-dose therapy will cause tinnitus
Life threatening in overdose: will cause hyperventilation, hearing changes, metabolic acidosis and confusion
Aspirin contraindications/ caution?
Children <16 due to risk of reye’s syndrome
Pt’s with aspirin hypersensitivity
Should be avoided in the 3rd trimester of pregnancy where prostaglandin inhibition may lead to premature closure of the ductus arteriosus
Caution: people with peptic ulcers, provide gastric protection
Gout pts: can trigger an acute attack
Aspirin interactions?
Interacts with other antiplatelet agents and increases risk of bleeding
Aspirin dose and route?
ACS: Should be prescribed as a once only loading dose of 300mg followed by a regular dose of 75mg daily
Acute ischaemic stroke: 300mg QD for 2 weeks before switching to 75mg
Long term prevention of thrombosis: Useful after an acute event or in people with AF, 75mg QD
Pregnant women at mod-high risk of pre-eclampsia: 75–150 mg once daily from 12 weeks gestation until the birth of the baby.
Max daily dose of 4g: take with food to minimise gastric irritation
What would you tell the pt when prescribing Aspirin?
Safety net: This drug aims to prevent heart attacks, stroke and to prolong life.
Watch out for indigestion of bleeding symptoms- seek medical advice if these occur
Atropine clinical indications X 4/ drug class?
Muscarinic antagonist- emergency drug
Intraoperative bradycardia
Symptomatic bradycardia due to acute overdose of bblockers
Treatment of poisoning caused by organophosphorous insecticide/ nerve agent
GI disorder caused by SM spasms
Atropine MOA?
Atropine metabolism/ elimination?
It binds to and inhibits muscarinic acetylcholine receptors producing a wide range of ACh effects- M1-M5 receptors
By the liver. 13-50% excreted unchanged in the liver
Atropine SEs? x6
Constipation, urinary retention and anhidrosis (elderly) Dizziness Photophobia (eye) Drowsiness Dry mouth Flushing
Atropine contraindications/ cautions?
Pts with: Acute closure glaucoma GI obstruction Paralytic ileus Pyloric stenosis Severe UC
Caution: adults: acute MI, arrhythmias, autonomic neuropathy and elderly with polypharmacy: 2 or more antimuscarinics= toxicity
Atropine interactions
add
Atropine dose and route
add
Indications for morphine (X4) and drug class
Rapid relief for acute severe pain e.g post op pain and MI
Relief of chronic pain where other 2 rungs of ladder failed
For relief of breathlessness in end of life care
To relieve breathlessness and anxiety in acute pulmonary oedema (used with oxygen, nitrates and furosemide)
It’s an opioid analgesic
Morphine MOA
Works mainly by binding to mu-opioid receptor: activation of descending inhibitory pathways of the CNS AND inhibition of the nociceptive afferent neurons of the PNS
Morphine SEs
Constipation: Mu receptor activation increases SM tone and reduces motility
N+V: from activated chemoreceptive trigger zone
Drowsiness
Respiratory depression: reduces respiratory drive
Confusion
Pupillary constriction: due to activation of Edinger-westphal nucleus
Neurological depression in higher doses
Itchy skin due to histamine release