HIGH RISK DRUGS Flashcards
What are the CI of lithium?
Addison’s disease Cardiac insufficiency Dehydration Low Na+ diet Untreated hypothyroidism
What are cautions of lithium?
Avoid abrupt withdrawal Cardiac disease Concurrent ECT (May lower seizure threshold) Epilepsy Qt prolongation Can exacerbate psoriasis
What is the association with long term use of lithium?
Thyroid disorders
Mild cognitive and memory impairment
Patients should b maintained on lithium after 3-5 years only if benefit is ther.
What are the signs of overdose of lithium?
- GI disturbances:(vomiting and diarrhoea)
- visual disturbances (blurred vision)
- CNS disturbances: (fine tremors increasing to coarse, confusion, drowsiness, lack of co-ordination, restlessness, stupor, high Na+, incontinence)
Severe overdosage:( >2mmol/L)
Seizures Cardiac arrhythmia (bradycardia, heart block) BP changes Circulatory failure Renal failure Coma Sudden death
STOP TREATMENT IMMEDIATELY
What is the conception, contraception advice and pregnancy advice with lithium?
Effective contraception during treatment
Avoid during pregnancy, especially in the 1st trimester (risk of teratogenicity and cardiac abnormalites)
What are the serum level monitoring requirements of lithium?
-Serum concs: 0.4-1mmol/L
(lower end of the range for maintenance and the elderly)
Blood samples should be taken 12 hours.
0.8-1mmol/L: acute episodes of mania and relapse patients and sub-syndromal symptoms
When should serum levels of lithium be measured?
- Weekly after initiation and after each dose change until concs are stable.
- Then every 3 months thereafter.
What are the other factors that should be monitored for lithium?
Asses renal, cardiac, and thyroid function before treatment initiation.
Cardiac function- regularly
ECG is recommended in patient with CVD or risk factors.
FBC can be measured before treatment
-BMI or body weight, serum electrolytes, thyroid, eGFR before starting and every 6 months.
What advice should be given when stopping lithium treatment?
Do not stop immediately unless told by dr.
Dose should be reduced gradually over at least 4 weeks (preferably over 3 months)
Abrupt withdrawal increases risk of relapse.
What are the patient/career advice for lithium?
- Patients should stay on one brand
- They have have the treatment pack
- Keep constant and adequate salt and water intake (especially if they have an infection or during hot spells)
- Avoid otc NSAIDs, alcohol and Na+ containing antacids
- Risk of feeling sleepy- be careful when driving.
Report signs of benign intracranial HTN, hypothyroidism, renal dysfunction
What drugs increase the toxicity of lithium?
ACEI, ARBS Loop diuretics, thiazides NSAIDS K + sparing diuretics SSRIs (and CNS effects) TCAs Aldosterone antagonists
Metronidazole (MAY increase risk of toxicity)
What drug increases risk of ventricular arrhythmias For lithium?
Amiodarone
What drugs increase the risk of neurotoxicity of lithium?
Methyldopa Phenytoin Carbamazepine Diltiazem Verapamil
What is the target rage for carbamazepine?
4-12mg/L measure after 1-2 weeks therapy
What are the monitoring requirements of carbamazepine?
FBC
Renal function
Liver function
What are the warning signs of carbamazepine?
Toxicity: incoordination, blurred vision, Diplopia (double vision), Nystagmus, Ataxia, Arrhythmia, N + V, Low Na+, Diarrhoea. STOP TREATMENT!
Blood disorders: leucopenia, thrombocytopenia (fever sore throat, fever, bruising)
Skin disorders: Toxic epidermal necrolysis (rash)
Hepatic disorders
Antiepiletic hypersensitivity syndrome: feve, rash, swollen lymph nodes.
What is the major route of Elimination of carbamazepine?
Hepatic metabolism
Cyp450 enzyme inducer
Which vitamin is recommended in carbamazepine and phenytoin? And for which type of patients?
Vit D Consider in patients: -who are immobilised for long periods -have inadequate sun exposure -have inadequate dietary intake