guanfacine Flashcards
Main cautions for guanfacine - TDP
caution with
Bradycardia (risk TDP)
Heart block (risk TDP)
History CVD
History QT interval prolongation
Hypokalaemia (risk TDP)
Main interactions are to do with (2)
bradycardia
hypotension
Info re somnolence and sedation
Somnolence and sedation may occur, predominantly during the first 2-3 weeks of treatment and with dose increases; manufacturer advises to consider dose reduction or discontinuation of treatment if symptoms are clinically significant or persistent.
Signs of overdose
hypotension, initial hypertension, bradycardia, lethargy, and respiratory depression
patients who develop lethargy should be observed for development of more serious toxicity for up to 24 hours
Contraception needed?
effective contraception in females of childbearing potential.
Monitoring
- baseline test to identify if at risk of somnolence, sedation, hypotension, bradycardia, QT prolong, arrhythmia
- include assessment of CV status
- monitor for signs of these adverse effect weekly during dose titration and then every 3 months for first year, then every 6 motnhs
- monitor BMI before treatmentt, then every 3 months for 1 year, then every 6 months
- more frequent monitoring advised following dose adjusmnets
- monitor BP and pulse during dose downward titration and following discontinuation
True of false - you need to measure BMI after treatment
false
take BMI before, then every 3 months for 1 year, then every 6 months
True or false - you need to monitor BP and pulse regularly in pt taking guanfacine
False - monitor these during dose downward titration and following discontinuation of treatment
True or false - unlike the amphetamines and atomoxetine, you can abruptly withdraw
False - avoid abrupt withdrawal; consider dose tapering to minimise potential withdrawal effects.
Is there any special directions for administration for guanfacine?
Manufacturer advises avoid administration with high fat meals (may increase absorption).
Labels
Warning: This medicine may make you sleepy. If this happens, do not drive or use tools or machines. Do not drink alcohol.
Swallow this medicine whole. Do not chew or crush.
What ages is it licensed for
children only 6-17
Main interactions are to do with bradycardia and hypotension. What are the other interactions?
It is a substrate - affected by inhibtiors (increased levels) and inducers (reduced levels)
Why do you need to measure pulse and BP on downward dose titration/discontinuation?
Due to risk of blood pressure increase upon discontinuation, guanfacine should be gradually tapered at a rate of no more than 1 mg every 3 to 7 days. Blood pressure and pulse should be monitored when discontinuing treatment.
