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Flashcards in TDM DRUGS Deck (53)
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1

What is the difference between HYPERglyceamia and HYPOglyceamia symptoms?

HYOGLYCEAMIA-

Think how you feel if you have not eaten sugar for a while:

Dizzy, head hurts, shaky, hungry, cannot see or think straight, sweaty

 

HYPERGLYCEAMIA:

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

 

2

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  

3

What is the desired serum concentration of Digoxin?

1 - 2 mcg / L

4

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

5

What are the symptoms of DIGOXIN toxicity? (i.e. levels over 2 mcg/ L)

Gastro:

Nausea and vomitting

Abdominal pain

Anorexia (weight loss)

Cardiac:

Bradycardia- (HR under 60 bpm)  heart slowed down too much by digoxin

Arrythmias (irregular heart beat)

Mental:

Delirium (confusion)

Visual disturbance- blurred, seeing yellow, blind spots

6

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)

7

We need to monitor the plasma concentration of Digoxin closely. When should levels be taken?

at least 6 HOURS after a dose given

8

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.

Hypomagnesaemia

Hypocalcaemia

9

How is digoxin excreted? Therefore what do we need to monitor and decrease dose if impaired?

Renally

decrease dose if patient has renal impairment

10

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

11

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

12

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?

Macrolides: Erythromycin

Clarythromycin, Azithromycin

Ciclosporin

Itraconazole

Amiodarone (but not through CYP)

13

Rifampicin and St Johns Wort are both CYP450 enzyme inhibitors. What TDM drug do they reduce the concentration of?

Digoxin

14

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:

Furosemide, Bumetanide

Bendroflumethiazide, indapamide, chlortolidone

Potassium sparing diuretics are Okay:

Amiloride Triamterene

Spironolactone (this can increase [Digoxin]), Eplerenone

15

What drugs other than diuretics can interact with digoxin due to their Hypokaleamic effects?

Amphotericin (Antifungal!)

 

16

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

17

What happens if a CCB is administered to someone on Digoxin?

Plasma conc of digoxin increased by:

Diltiazem

Nicardepine

Nifedipine

Verapamil (also increases risk of AV BLOCK & bradycardia [slows rate])

 

18

What are the signs of Lithium toxicity?

GI disturbance warning signs:

Vomitting, Diarrohea

Then Mostly CNS effects:

Fine Tremor to start then coarse tremor

Involuntary movement (ataxia)

Involuntary eye movement (Nystagmus)

Blurred vision

Thirst- due to hypernatreamia?

Severe toxicity (level over 2 mmol/L):

Convulsions

Coma

Renal failuire

19

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

20

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!

21

What three drugs do you legally have to provide a patient alert card with?

Lithium

Steroids

Anticoagulant

22

Lithium interacts with

ACE inhibitors/ ARB's

NSAIDS

What is this interaction?

Ace inhibitors / ARB's and NSAIDs can decrease renal perfusion

Lithium excreted by Kidneys

Lithium levels risk= lithium toxicity

23

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

24

Which antibiotic could possibly cause Lithium toxcity/ levels to rise?

Metronidazole

25

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

26

What type of seizures can phenytoin be used in?

Focal

Tonic- clonic

Myoclonic

But not first/ 2nd line in any. Its use is fizzling out.

All types of seizure but Absent!

27

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

28

What are the symptoms of Phenytoin toxicity?

CNS:

Nystagmus (involuntary eye movement)

Ataxia (involuntary body movement)

Slurry speech

Confusion

suicidal thoughts

HYPERGLYCEAMIA

Double vision (diplopia), blurred vision

NB: Similar to Lithium toxicity: remember the differentials (hyperglyceamia, no convulsions)

29

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)

acne

 

Blood disorder:

Fever, sore throat, mouth ulcers, bruising, bleeding

 

 

30

With phenytoin, we should monitor ECG & BP with IV use.

Should also monitor _____ function, especially in elderly

LIVER

Phenytoin hepatically metabolised: Caution in Hepatic impairment