High Risk Drugs Flashcards
What are the FOUR indications of lithium (4)
- Prophylaxis and Tx of mania and hypomania
- Prophylaxis and Tx of bipolar
- Treatment and prophylaxis of aggressive or intentional self-harm
- Treatment and prophylaxis of recurrent depression
Long term use of lithium has been associated with what?
Mild cognitive and memory impairment and thyroid disorders
Why is it important to maintain a patient on the same brand of lithium?
Not all brands are bioequivalent. Brands are typically within 5% (95%-105%)
Changing the preparation would require the same precautions and monitoring as initiating treatment for the first time
What are the two different Lithium salts? Name the brands of each
How should lithium be prescribed?
Lithium Carbonate: Camcolit, Priadel, Liskonium tablets
Lithium Citrate: Li-liquid, Priadel liquid (citrate only comes as a liquid)
Rx by brand
Signs and Symptoms of lithium toxicity
(The standard overdose Sx and then the severe overdose Sx)
R - Renal disturbances: polyuria, incontinence, hypernatremia
E - EPSE, fine tremor increasing to course tremor, ataxia, myoclonus, muscle weakness
V - Visual disturbances
N - Nervous system disturbances - Confusion and drowsiness increasing to incoordination, restlessness and stupor
G - G.I disturbances (v, d)
Severe - Overdose seizures, cardiac arrhythmias (sino-atrial block, bradycardia and first degree heart block), BP changes, circulatory failure, renal failure, coma and sudden death
When is lithium normally taken and why?
When should serum concentrations be taken for lithium?
12 hours after dose (therefore dosing at night for level in the morning)
Standard target lithium range
Acute episodes of mania lithium range
Standard - 0.4 - 1 mmol/L
Mania - 0.8 - 1 mmol/L
Routine serum-lithium monitoring
Weekly after initiation and after each dose change until concentration sttable
Then every 3 months for the first year
Then every 6 months therafter
Which patient groups should be monitored at more regular intervals when taking lithium and how often are they monitored?
- >65
- Taking drugs that interact with lithium
- At risk of impaired renal or thyroid function
- Raised calcium levels or other complications
- Have poor sx control or poor adherence
- Whose last serum-lithium concentration was > 0.8 mmol/L
Should be monitored every 3 MONTHS
What other tests are performed before initation of lithium? (7)
Which of these tests are monitored after initiation and how often are these monitored?
- Renal
- Cardiac
- Thyroid
- ECG if CVD or RF for it
- Body-weight/BMI
- Serum electrolytes (spec. calcium)
- FBC
Every 6 months (body weight/BMI, serum electrolytes, eGFR and TFTs) - more regularly if impaired renal/thyroid function or raised calcium levels.
General side effects of lithium (5)
- Thyroid disorders (hypo/hyper thyroidism) -> monitor TFTs
pt counselling - Report weight gain/fatigue
- Renal impairment nephrotoxic and renally cleared -> monitor renal
Pt counselling - report polyuria/polydipsia
- Benign Intracranial HTN
Pt counselling - report persistent headache, visual disturbances
QT interval pro-longation
Lowers seizure threshold
Others: Weight gain, metallic taste in mouth, GI disturbances (particularly at initiation)
If a patient has persistent headaches and on lithium, what should you do?
Refer
Lithium can cause benign intracranial hypertension
Which electrolyte disturbance predisposes someone to lithium toxicity?
Hyponatremia
Lithium toxicity is made worse by sodium depletion, therefore what drugs should be avoided?
B2 agonists (salbutamol/terbutaline), Inhaled corticosteroids, diuretics (loop - furosemide), (TLD - indapamide), NSAIDs (nephrotoxic too), TCAs/SSRIs
Lithium and seizures - what drugs should be avoided?
Lowers seizure threshold
SSRIs, tramadol, quinolones
Lithium drug interactions (4)
- Increased risk of seizures -> quinolones, SSRIs, tramadol
- QT inteval pro-longation - Increased risk of arrythmias - quinolones, SSRIs, macrolides, amiodarone, antipsychotics, TCAs, sotalol, chloroquine, mefloquine (hypokalaemia - theophylline, B2 agonists, loop/thiazide diuretics)
- Decrease renal excretion (increased risk of lithium toxicity) - ACEi/ARBs NSAIDS, diuretics (loop/thiazide)
- Hyponatremia (b2 agonists, inhaled corticosteroids, TCAs/SSRIs, diuretics (loop/thiazide)
What is the patient advice regarding diet and fluid intake if on lithium therapy?
Maintain adequate fluid intake and avoid dietary changes which reduce or increase sodium intake.
Can lithium be used in pregnancy?
Teratogenic including cardiac abnormalities - avoid if possible
Especially in 1st trimester
In 2nd and 3rd trimester: dose may need to be increased but on delivery return abruptly to normal
General patient counselling lithium
- Avoid dehydration and big changes to level of salt in diet
- Seek medical advice if experience diarrhoea/vomitting -> dehydration
- Recognising signs of toxicity
- Adherance and monitoring
- Lithium treatment pack - Patient info booklet, lithium alert card and record book for lithium-serum concentration tracking
- Inform pharm before buying OTC products (ibuprofen and aspirin)
Over which period should lithium be discontinued?
Gradually - over a period of 4 weeks (preferably 3 months)
Can can relapse if discontinued abruptly
What is the therapeutic range for theophylline
10-20 mg/L
55–110 micromol/litre
When to take theophylline sample
4-6 hours AFTER dose
How is theophylline monitored?
5 days after starting oral thearpy and 3 days after every dose adjustment
What conditions/drugs increase and decrease theophylline levels
Increase concentration - heart failure, hepatic impairment, viral infections, elderly, enzyme inhibitors
Decrease concentration - smokers, alcohol, enzyme inducers
Signs of theophylline toxicity
‘Fast and Sick’
- Vomitting and GI effects (D and gastric irritations), hyperglycaemia
- Tachycardia (CNS stim - restlessness, agitation, dilated pupil)
- Arrythmias, convulsions, hypokalaemia
Theophylline drug interactions
Hypokalaemia - loop and thiazide diuretics, b2 agonists, corticosteroids
Convulsions - quinolones
What theophylline preparation should be prescribed by brand
MR
Where is theophylline metabolized
Liver
How is aminophylline dosed?
Based on IBW
Why is aminophylline used IV instead of theophylline?
Aminophylline is a stable mixture or combination of theophylline and ethylenediamine; the ethylenediamine confers greater solubility in water.
