What is the difference between HYPERglyceamia and HYPOglyceamia symptoms?
Think how you feel if you have not eaten sugar for a while:
Dizzy, head hurts, shaky, hungry, cannot see or think straight, sweaty
Just think how you feel if you're BUZZING:
Dry mouth, need water, lots of weeing, wetting bed, stomach pain
blood glucose concentration is high so fluid moves out of cells into circulation due to osmosis so you get dehydration
What is an ionotrope? What is a positive and what is a negative ionotrope?
A drug that alters the force or energy of heart contractions
So positive ionotrope (e.g. Digoxin, Amiodarone): increases force of contractions of heart, used in conditions such as decompensate Heart Failure, shock (severe hypotension) and Myocardial Infarction as they get blood pumping again!
NB: these do not increase rate, digoxin actually decreases the rate, just increase force of contraction. Digoxin used as rate control in AF, Amiodarone used as Rhythm.
Negative ionotropes: decrease force of contractions of the heart, used in conditions such as Hypertension to bring blood pressure down and Angina. Examples: Rate limiting CCB's, cardio-selective beta blockers e.g. bisoprolol, carvedilol, metoprolol, some anti-arrhythmics such as flecainide
What is the desired serum concentration of Digoxin?
1 - 2 mcg / L
What is the difference between bradycardia and tachycardia? What is the the classified pulse rate for these?
Bradycardia: slow heart rate: pulse under 60 bpm
Tachycardia: fast heart rate: pulse over 100 bpm
What are the symptoms of DIGOXIN toxicity? (i.e. levels over 2 mcg/ L)
Nausea and vomitting
Anorexia (weight loss)
Bradycardia- (HR under 60 bpm) heart slowed down too much by digoxin
Arrythmias (irregular heart beat)
Visual disturbance- blurred, seeing yellow, blind spots
Digoxin needs close monitoring. It slows the heart rate, but increases the force of contraction. We need to monitor the heart rate: When should we be worried?
If it falls below 60 BPM (i.e. becomes bradycardic)
We need to monitor the plasma concentration of Digoxin closely. When should levels be taken?
at least 6 HOURS after a dose given
Digoxin toxicity can be fatal. What electrolyte imbalance can precipitate digoxin toxicity?
HYPOKALEAMIA is a big one. We manage this by giving K+ sparing diuretics (e.g. spironolactone) and K+ supplements.
How is digoxin excreted? Therefore what do we need to monitor and decrease dose if impaired?
decrease dose if patient has renal impairment
What is digoxin used in?
Most use in persistent & permanent Atrial Fibrilation as RATE control
Has a role in Heart Failure
Role in Atrial flutters
Amiodarone is used in the rhythm control of AF.
Digoxin is used as rate control.
interaction between these 2 drugs?
Amiodarone INCREASES plasma concentration of digoxin
It is an ENZYME inhibitor but not one of the P450's (so not part of SICKFACES)
Digoxin dose needs to be decreased by 50% if given with Amiodarone
Digoxin is metabolised by the CYP450 enzyme system, primarily 2C19. It therefore has many interactions. Can you think of any drugs that increase its concentration?
Amiodarone (but not through CYP)
Rifampicin and St Johns Wort are both CYP450 enzyme inhibitors. What TDM drug do they reduce the concentration of?
Why does Digoxin interact with Diuretics?
Diuretics (Loop and thiazide/ thiazide- like) may cause HYPOKALEAMIA
Digoxin toxicity is precipitated by HYPOkaleamia
Therefore be careful with:
Bendroflumethiazide, indapamide, chlortolidone
Potassium sparing diuretics are Okay:
Spironolactone (this can increase [Digoxin]), Eplerenone
What drugs other than diuretics can interact with digoxin due to their Hypokaleamic effects?
Can you think why ACE inhibitors and NSAID's interact with digoxin?
Remember digoxin is excreted renally and caution in kidney impairment
ACE inhibitors and NSAID's can both decrease kidney function and precipitate digoxin toxicity
What happens if a CCB is administered to someone on Digoxin?
Plasma conc of digoxin increased by:
Verapamil (also increases risk of AV BLOCK & bradycardia [slows rate])
What are the signs of Lithium toxicity?
GI disturbance warning signs:
Then Mostly CNS effects:
Fine Tremor to start then coarse tremor
Involuntary movement (ataxia)
Involuntary eye movement (Nystagmus)
Thirst- due to hypernatreamia?
Severe toxicity (level over 2 mmol/L):
Lithium can cause problems in some of our organs. What are these, what would be the signs if their function had altered?
Kidney- monitor renal function
Sign of decline: Polyuria, Polydipsia
Thyroid- usually hypothyroidism
Signs: unexplained fatigue
Benign intracranial hypertension (high BP in brain)
Signs: persistent headache, visual disturbance
You know the target range for lithium is 0.4 - 1.0 mmol/L.
What is the target in acute episodes of mania?
0.8 - 1.0 mmol/ L- upper end of the range!
What three drugs do you legally have to provide a patient alert card with?
Lithium interacts with
ACE inhibitors/ ARB's
What is this interaction?
Ace inhibitors / ARB's and NSAIDs can decrease renal perfusion
Lithium excreted by Kidneys
Lithium levels risk= lithium toxicity
Why does Lithium interact with the Diuretics (loop, thiazide AND potassium-sparing)?
Diuretics can cause electrolyte disturbance
Hyponatreamia may be a result
Lithium levels influenced by sodium levels- lithium toxicity
Which antibiotic could possibly cause Lithium toxcity/ levels to rise?
Please note there is increased risk of neurotoxicity when Lithium is given with things like methyldopa, phenytoin, carbamazepine
& the rate limiting CCB's diltiazem and verapamil
There is increased risk of EPSE's when Lithium is given with antipsychotics
What type of seizures can phenytoin be used in?
But not first/ 2nd line in any. Its use is fizzling out.
All types of seizure but Absent!
Desired therapeutic range for Phenytoin?
Why is it so important to monitor phenytoin levels?
10 - 20 mg/ L
= 40- 80 micromol/L
Non-linear relationship between dose and plasma conc: small change in dose= big change in conc
What are the symptoms of Phenytoin toxicity?
Nystagmus (involuntary eye movement)
Ataxia (involuntary body movement)
Double vision (diplopia), blurred vision
NB: Similar to Lithium toxicity: remember the differentials (hyperglyceamia, no convulsions)
Phenytoin is related to SKIN & BLOOD disorders
What does the patient need to look out for?
Skin- look out for RASH
Phenytoin also causes:
HIRSUTISM (excess hair growth)
gingival hypertrophy (enlarged gums)
Fever, sore throat, mouth ulcers, bruising, bleeding
With phenytoin, we should monitor ECG & BP with IV use.
Should also monitor _____ function, especially in elderly
Phenytoin hepatically metabolised: Caution in Hepatic impairment