High Risk Drugs Flashcards
Loading dose for amiodarone
200mg TDS 7 days
200mg BD 7 days
200mg daily maintenance
Side effects & sign of toxicity with amiodarone
***Pulmonary toxicity*** Corneal micro deposits - reversible Phytotoxicity -Grey discolouration Hypo/hyper thyroidism HEPATIC
Tremor
Sleep disturbance
Arrythmia
Nausea
Monitoring Amiodarone & duration
LFTs Thyroid - before & every 6 months Potassium - before treatment Chest X-ray - before ECG
Patient advice with Amiodarone
Shield from sunlight & use wide spectrum sun cream
Warn drivers dazzled from headlights at night
Warn pt clinical effects may occur few months after stopping treatment - long half life 60-142days
Interaction of amiodarone
Enzyme inhibitor
Amiodarone & warfarin - amiodarone inhibit warfarin metabolism - enhanced anticoagulantion effect
Amiodarone & b blocker - increased risk of bradycardia, AV block and myocardial depression
Amiodarone & lithium - risk of arrhythmia
Amiodarone & ciclosporin & digoxin - plasma concentration ciclosporin & digoxin increased by amiodarone
Orlistat - reduces plasma conc of amiodarone
Statin - increased myopathy
AVOID GRAPEFRUIT JUICE
Digoxin therapeutic range
Cardiac glycosides - used in AF, tachycardia & heart failure
Increases force of myocardial contraction
0.8 - 2mcg/L
Digoxin monitoring
Electrolytes - K+, Mg+ and Ca+
Heart rate
Renal function
Which electrolyte causes digoxin toxicity?
Potassium
HYPOkalaemia
Manage by potassium sparing diuretic or potassium supplement to increase potassium
Symptoms of digoxin toxicity?
Cardiac block, arrhythmia
Lethargy, weakness, confusion
N&V, abdominal pain, diarrhoea
Blurred vision - YELLOW vision
Interactions of Digoxin
Amiodarone - plasma conc of digoxin increased by amiodarone
Erythromycin - plasma conc of digoxin increased by erythromycin
Rifampicin - plasma conc of digoxin reduced
Diuretics - toxicity if HYPOkalameia occurs
CCB - plasma conc of digoxin increased by ccb
Therapeutic range for Lithium?
Treats - mania, bipolar, recurrent depression
0.4-1 mmol/L
Lithium monitoring
THYROID
Lithium concentration - every 3 months
Renal & Thyroid - every 6-12 months
Cardiac function
Maintain sodium levels - hyponatraemia
Toxic symptoms of lithium?
Fine tremor Nystagmus Hypothyroidism Hypertension Slurred speech Convulsions Blurred vision Confusion
Counselling points of Lithium
Same brand Maintain sodium levels OTC interactions - Gaviscon Avoid alcohol Driving - sleepy Do not stop unless told by DR
Lithium interactions
ACEi & NSAIDS, metronidazole, SSRI, excretion of lithium reduced by ace results lithium toxicity
Diuretics - sodium depletion hyponatraemia
Amiodarone - risk of ventricular arrhythmia
EPS - clozapine , haloperidol, risperidone, flupentixol
Monitoring of methotrexate?
FBC - blood dycrasias
LTFS - report abdominal pain, jaundice, dark urine test before treatment
Pulmonary - cough, fever, shortness of breath
Renal - toxic
Counselling point for methotrexate?
Pregnancy - wait 6 months before attempting to conceive & protection whilst on treatment
Annual flu vaccine - NOT LIVE
Avoid NSAID, IBUPROFEN, aspirin - if given rx monitor concentration closely
Folic acid - prevent methotrexate included mucositis or myleosupression. Not given at same time
Methotrexate interactions
Acitretin - risk of hepatotoxity
NSAIDS, penicillin, ciprofloxacin, doxycycline, tetracycline, sufonamides, cicosporin , PPI, lefunomide, aspirin
Haematological toxicity - co-trimoxazole & trimethoprim
Therapeutic range for Phenytoin?
10 to 20mg/L
Monitoring Phenytoin?
Serum concentration ECG Blood pressure Liver function FBC Vitamin D
Symptoms of toxicity Phenytoin?
With or after food
Hyperglycaemia, blurred vision Skin rash disorders Blood disorders - fever, sore throat, brushing, bleeding, mouth ulcers Excessive hair - on face Constipation Low vit D - rickets, osteomalacia
Interactions Pheytoin
NSAIDs - effects of phenytoin enhanced
Amiodarone - inhibits metabolism of phenytoin
Warfarin - phenytoin accelerate metabolism of warfarin
Cimetidine - inhibits metabolism of phenytoin
Fluoxetine - plasma conc of phenytoin increased by fluoxetine
Inducers - reduce plasma conc phenytoin
Therapeutic range for Theophylline?
10-20mg\L
Monitoring for Theophylline?
Plasma concentration
Lung function
Serum potassium
Symptoms of Theophylline
Hyperglycaemia
Tachycardia HYPOkalameia Hyperglycaemia Agitation Conclusion
Chest - wheeze, tight chest, cough
Theophylline councelling?
OTC - avoid fluconazole &
Brand only
Inform GP before starting/ stopping smoking
Theophylline interactions
Quinolones - risk of convulsions
St. John/rifampicin - conc of theophylline reduced
Fluconazole/macrolide/contraception- conc of theophylline increased
Beta 2 agonist - HYPOkalameia
Diuretics /steroids - severe asthma potentiated
Warfarin INR
takes 48-72hrs for anticoagulation effect to develop fully
Bleeding major or minor INCREASED INR
- stop warfarin
- vit k IV - restart warfarin INR less 5
- repeat if INR still high after 24h
No bleed INR LOW - risk of clot
INR >8 stop warfarin
ORAL vit k restart warfarin INR <5
INR 5-8 - withhold 1 -2 doses of warfarin
Reduce maintenance dose
Measure INR 2-3days after
Antidote for Warfarin?
Phytomenadione
Dose of warfarin?
Begin - 5-10mg first day measure 1-2 days
Maintenance - 3-9mg take same time each day
Monitor - every 3 months
Warfarin monitoring
INR
Renal function