Anti-Hypertensive Drugs II Flashcards
What is Clonidine/Catapres™ (also methyldopa)?
Clonidine is a sympatholytic medication used to treat high blood pressure, attention-deficit/hyperactivity disorder, anxiety disorders, withdrawal (from either alcohol, opioids, or smoking), migraine, menopausal flushing, diarrhea, and certain pain conditions. It is classified as a centrally acting α2 adrenergic agonist.
Drug costs $4 (generic) to $37 (branded) to $108 (Catapress™ patches) per month)
To what drug class does clonidine belong?
Pharmacologic class => central α2 agonist
Therapeutic class–antihypertensive, adjunct to Rx of opioid withdrawal, prophylaxis of migraine
Describe the pharmacodynamics of clonidine.
Stimulates α2 adrenoceptors in brainstem => down-regulation of sympathetic output
Describe the pharmacokinetics of clonidine.
- Onset 1 h, duration 8 h
- F~85%
- Also available as cutaneous patch
What toxicity is associated with clonidine?
- Withdraw gradually because of risk of rebound HTN
- Risk of bradycardia in sinus node disease
- Letharagy, fatigue, depression
What interactions should be noted in patients taking clonidine?
- Additive effects with most other antihypertensives
- Additive sedation with other CNS drugs
What special considerations should be made for patients on clonidine?
- Pregnancy class C
- Avoid in patients with renal insufficiency
What is the route/dose for clonidine?
- Begin with 0.1 mg po bid, up to 1.2 mg per day
- Transdermal begin with 0.1 mg per 24 h as a 7-day patch
What should be monitored in patients on clonidine?
BP and HR, fatigue
What is Trimethaphan/Arfonad™ ?
Trimethaphan is a drug that counteracts cholinergic transmission at the ganglion type of nicotinic receptors of the autonomic ganglia => blocks both the sympathetic nervous system and the parasympathetic nervous system.
It acts as a non-depolarizing competitive antagonist at the nicotinic acetylcholine receptor, is short-acting, and is given intravenously ONLY => NOT for long term management of HTN
To what drug class does Trimethaphan belong?
Pharmacologic class => ganglionic transmission blocker
Therapeutic class => antihypertensive
Describe the pharamcodynamics of Trimethaphan.
- Blocks nicotinic transmission within both sympathetic and parasympathetic ganglia (NN receptors)
- Produces veno- and vaso-dilatation
Describe the pharmacokinetics of Trimethaphan.
- Useful only when given iv
- Produces fall in BP within minutes
- Partly metabolized, and partly excreted by kidneys
What toxicity is associated with Trimethaphan?
- Watch out for sudden, severe drop in BP and HR
- Reduction in just about any sympathetic or parasympathetic response
What drug interactions are associated with Trimethaphan?
Additive effects with most other anti-hypertensives
What special considerations should be accounted for in patients on Trimethaphan?
- Patients are quite miserable, hence only used during general anesthesia
- Helps to tilt patient to help control BP
What are the indications/dose/route for Trimethaphan?
- Given by iv infusion => only to treat HTN crisis or for controlled hypotension during cardiovascular surgery
What should be monitored in patients on Trimethaphan?
Minute to minute monitoring of BP (and HR)
What is Reserpine?
Reserpine is an indole alkaloid, antipsychotic and antihypertensive drug, although because of the development of better drugs for these purposes and because of its numerous side-effects, it is rarely used today.
The antihypertensive actions of reserpine are a result of its ability to deplete catecholamines from peripheral sympathetic nerve endings.
- Controls HR, increases contractility and peripheral vascular resistance
- NOT USED TODAY FOR LONG TERM MANAGEMENT OF HTN
What drug class does reserpine belong to?
Pharmacologic class => Rauwolfia alkaloid (used to treat HTN)
Therapeutic class => antihypertensive
Describe the pharmacodynamics of Reserpine.
- Binds to vesicles that contain NE or serotonin, preventing their uptake, and ultimately depleting the neuron of NE (or serotonin)
- This effect takes 2-3 weeks to develop, and includes neurons and also the adrenal medulla
Describe the pharmacokinetics of Reserpine.
- Good oral bioavailability, but biologic effects take 2-3 weeks to develop (via slow depletion of NE from vesicles)
What toxicity is associated with Resperine?
- Dizziness
- Orthostatic hypotension
- Depression
What interactions should be considered in patients on Reserpine?
Additive effects with most other anti-hypertensives
When was Reserpine approved by the FDA and what is historically significant about Reserpine?
- Approved by the FDA in 1953
- First antihypertensive drug approved, and first sympatholytic drug approved by the FDA
- in 1960’s, drugs included only reserpine, HCTZ, and hydralazine
What are the indications/douse/route for Reserpine?
- For HTN
- 0.1-0.2 mg po q day
What should be monitored in patients on Reserpine?
BP, sympathetic tone, depression
