Digoxin - Flashcards
Digoxin effects on heart rate / contraction
Negatively chronotrophic - reduces rate
Positively inotrophic - increased force of contraction
How does digoxin work in AF
Increases Vagal parasympathetic tone
Digoxin effect in heart failure
Inhibits NaKATPase pumps -> Na accumulates in cell -> ca accumulation -> increased force
Digoxin adverse effects
Bradycardia, GI disturbance, rash, dizziness, visual disturbance
Important to remember about digoxin therapeutic dose
Close to toxic -> arrythmias
Who can never have digoxin
Second degree heart block
Intermittent complete heart block
Ventricular arrythmias
Which electrolyte abnormalities increase risk of digoxin toxicity
Hypokalaemia
Hypomagnesia
Hypercalcaemia
Under which circumstance should digoxin dose be reduced
Renal failure
Eg if drugs causing hypokalaemia -> increased risk of digoxin toxicity
Loop and thiazide diuretics
Need a rapid effect of digoxin - how prescribed
Loading dose 500micrograms
Followed by 250-500 micrograms 6 hours later
Usual maintenance dose of digoxin
125-250 micrograms
What is the reverse tick sign on ECG
St depression from therapeutic digoxin
Dipyridamole uses
first line TIA , second line ischemic stroke (if clopidogrel contraindicated)
Induce tachycardia for myocardial perfusion scan
What’s normally given with dipyridamole in second line ischemic stroke
Aspirin
Mechanism of dipyridamole
Antiplatelet and vasodilator
Dipyridamole adverse effects
Headache, flushing, dizzy, GI
Risk of bleeding, thrombocytopenia
Caution using dipyridamole in who
Ischemic heart disease, aortic stenosis, heart failure
As may exacerbate
Dipyridamole interactions (2 types)
Inhibits uptake of adenosine -> risk of cardiac arrest
Increased bleeding with other antiplatelets / anticoagulants
Loop diuretics egs
Furosemide
Bumetanide
Loop diuretic uses
Relive breathlessness in pulmonary oedema
Treatment of fluid overload eg. Heart / liver / renal failure
Loop diuretics mechanism (2)
Loop or henle - inhibit Na/K/2Cl co transporter
Dilation of capacitance veins
Loop diuretics adverse effects
Headache and dehydration.
Low electrolyte states
Hearing loss and tinnitus
Why do loop diuretics cause hearing problems
NaKCl transporter is used in regulating endolymph composition in inner ear
Who should never get loop diuretics
Hypovolemia
Dehydration
Loop diuretics use in caution when
Risk of hepatic encephalopathy
Hypokalaemia , hyponatraemia and gout
What drugs to loop diuretics effect
Any that are excreted by the kidneys
Eg Lithium levels increase due do reduced excretion
Digoxin toxicity due to hypokalaemia
Increase ototoxicity / nephrotoxicity of aminoglycosides
Eg loop diuretics prescription for acute pulmonary oedema
Furosemide IV 40mg
Eg of potassium sparing diuretic
Amiloride (co-amilofruse / Co-amilozide)
Why are potassium sparing diuretics often used with other diuretics
They are weak diuretics and used with stinger to counteract potassium loss
Where does amiloride act
Distal convoluted tubules
Who should not get potassium sparing diuretics
Renal impairment
Hyperkalaemia
Which drugs should not be given with potassium sparing diuretics
Potassium elevating - oral supplements / aldosterone antagonists
When might use amiloride over spirolactone
Hypertension due to hyperaldosteronism (conns) has amiloride directly effects ENaC channels
When spirolactone adverse effects eg gynaecomastia are not acceptable
Thiazide like diuretic egs
Bendroflumethazide, indapamide, chlortalidone
Thiazide diuretics uses
Alternative first line for hypertension where CCBs otherwise used.
Add on treatment for hypertension
When are CCBs not used in hypertension
Oedema / heart failure
Mechanism of thiazides
Inhibit Na/Cl co transporter in distal convoluted tubule
Vasodilation
Thiazide diuretics adverse effects
Hyponatraemia , hypokalaemia -> arrythmias
Impotence
Who should never get thiazide diuretics ?
Avoid in?
Hypokalaemia
Hyponatraemia , gout
Bendroflumethazide prescription
2.5mg daily
Why are thiazides good for combo with ACEi
Thiazide -> hypokalaemia (RASS system)
ACEi -> hyperkalaemia (block it )
Have a synergistic blood pressure lowering effect
Eg of dopaminergic drugs for Parkinson’s
Levodopa as (co-careldopa, co-beneldopa), ropinirole, pramipexol
Which dopaminergic drugs used for early vs late Parkinson’s
Early - ropinirole, pramipexol (as dopamine agonists)
Late - levodopa
What and where is there a deficiency of in Parkinson’s
Dopamine in nigrostriatal pathway
Dopaminergic adverse effects
Nausea, dizzy, confusion, hallucinations, hypotension
Major issue with Levodopa
Wearing off effect - symptoms get worse at end of dosage interval.
Increasing dose / frequency -> dyskenesias (movements)
With both called on-off effect
Cautions with dopaminergic drugs
Existing cognitive / psychiatric disease
Elderly
Cardiovascular disease
Which drugs have opposite effect to levodopa
Antipsychotics, metoclopramide
Digoxin uses
AF / flutter (usually less effective than b blocker / ccb)
Heart failure
How do emollients work
Replace water in dry skin and have oils that prevent water loss
Emollients uses
Dry skin conditions eg eczema / psoriasis
Adverse effects of emollients
Greasy skin
Worsen acne vulgaris / folliculitis by blocking pores
Egs of fibrinolytic drugs
Alteplase, streptokinase
Fibrinolytic drug uses
Acute ischemic stroke (within 4.5 hours)
Acute STEMI
Pulmonary embolism with haemodynamic instability
What gives better results than fibrinolytic drugs for STEMIs
PCI
Other word for fibrinolytic drugs
Thrombolytic
Mechanism of thrombolytics
Dissolve fibrinous clots -> re canalise vessels
Fibrinolytic drugs adverse effects
Nausea vomiting bruising bleeding
Hypotension
What can reperfusion of brain / heart tissue ->
Cerebral oedema
Arrythmias
Why shouldn’t streptokinase be given as a repeat prescription
Development of anti streptokinase antibodies
Contraindications to fibrinolytic treatment
Bleeding (disorders, recent surgery / trauma, hypertension, peptic ulcers…)
When using fibrinolytic treatment for stroke what must be ruled out
Intracranial haemorrhage
Gabapentin and pregabalin uses ? Specific use for each ?
Focal epilepsies (w or w/o 2 generalisation)
Neuropathic pain
Gabapentin - migraine prophylaxis
Pregabalin - generalised anxiety disorder
Mechanism of Gabapentin
Bunds to voltage gated ca channels -> inhibits neurotransmitter release
Gabapentin / pregabalin side effects
Drowsy, dizzy, ataxia (usually improve after few weeks)
Gabapentin / pregabalin reduced dose in
Renal impairment (as eliminated )
Gapapentin / pregabalin interactions
Effects may be enhanced when combined with other sedating drugs eg bendodiazepines
Prescription of Gabapentin
Start at low dose and titrated up to mink use adverse effects
H2 antagonist eg
Ranitidine
H2 antagonist uses
Peptic ulcer disease
GORD and dyspepsia
What is often preferred to h2 antagonists
PPIs
Mechanism of h2 antagonists
Reduce gastric acid secretion
Warning with h2 antagonists
Can disguise symptoms of gastric cancer (remember not to just treat symptoms )
What is benefit of h2 antagonists over PPIs and eg?
Faster action - suppress acid secretion pre op
Egs of heparins
Enoxaparin, dalteparin, unfractioned heparin
Uses of heparins and fondaparinux
Venous thromboembolism VTE prophylaxis and treatment of DVT / PE ( LMW Heparin)
Acute coronary syndrome
2 key components of final common coagulation pathway
Thrombin
Factor Xa
How does unfractioned heparin work
Activates antithrombin -> inactivates Xa and thrombin
Eg of LMW heparins
Dalteparin, enoxaparin
Fondaparinux mechanism
Inhibits Xa
Adverse effects of heparins and fondaparinux
Bleeding
Injection site reactions
Heparin induced thrombocytopenia
When should anticoagulants be used cautiously
Clotting disorders, severe hypertension, recent surgery / trauma, renal impairment
Drug for reversing anticoagulation
Protamine
Precribing for VTE prophylaxis
Enoxaparin 40mg sc daily /
Dalteparin 5000 units so daily
Where should sc drugs be given
Sub cut tissue of abdominal wall
What is APTR ? Usual target?
Activated partial thromboplastin ratio
1.5-2.5
What is the APTR Usually measuring ? How often should it be checked
Anticoagulant effect of UFH .
6hrly
How are patients diagnosed with VTE treated ? Why?
LMW heparin and warfarin
Because warfarin inhibits protein C / S (anticoagulants) before inhibiting clotting factors. LMW heparin provides cover period during this time
