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14 Cards in this Set
- Front
- Back
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Centrally acting antihypertensives
- MOA - Drugs in class |
1. Alpha-2 adrenoreceptor agonists, which reduce BP by reducing symptathetic tone
2. Clonidine, Methyldopa & Moxonidine (SAS) |
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Centrally acting antihypertensives
- Indications - Clinical usefulness |
Hypertension
- Methyldopa is safe in pregnancy unlike any other antihypertensive - Class is second line for hypertension because of decreased tolerability and lack of evidence for long term benefit; moxonidine showed excess deaths in HF Clonidine is also used for - Menopausal flushing & prevention of migraine (ltd evidence) - Diagnosis of phaeochromocytoma - ADHD - Managing opiod withdrawal - Adjunct in anaesthesia - Adjunct in analgesia (specialists) |
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Methyldopa
- brand - forms - dose - dose adjustment |
ALDOMET & HYDOPA
250mg.100 tabs 125-250 bd, max 500mg qid Adjust at 2 day intervals Sedating effect exacerbated by dose increase - increase doses at night first |
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Aldomet
- CI - Considerations - Preg/ BF |
- Active hepatic disease (CI)
- Phaeochromocytoma (CI) - Depression: may exacerbate (caution) Preg: A BF: Safe to use |
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Hydopa
- Adverse Effects |
Common
- #1 sedation - dizziness - dry mouth, fever, headache, nausea, diarrhoea Infrequent - haemolytic anemia, depression, sore tongue, impotence, sleep disturbance Rare hepatotoxicity, pancreatitis, blood dyscrasias |
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Hydopa
- counselling |
1. L1
2. L16 3. Take increased doses at night |
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Aldomet
- What monitoring? |
FBE and LFT during first 6/12 of treatment
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Clonidine
- dose form - brand |
Catapres
100mcg.100, 150mcg.100 TABS 150mcg/mL.1mL INJECTION |
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Clonidine dosing
1. HTN 2. Menopausal flushing 3. ADHD 4. Opioid withdrawal 5. Diagnosis of phaeochromocytoma |
(1)150-300mg bd (initate at 50-100mg bd, and increase q2-3/7 by 100-200mg)
(2)25mcg-75mcg bd (3) 50mcg d (1-3 dd) to start, increase by 50mcg prn to max 4mcg/kg/d (4) 5-15mcg/kg/d (tds) for 7/7 then taper for 3 days (5) 300mcg stat |
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Catapres
- CI - Caution |
CI: Sick sinus syndrome and heart block
Cautions - depression (may exacerbate) - diabetes (transient increase in BGLs) - May exacerbate vasospastic conditions, PVD, CRF, MI, CVD |
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Catapress
- A/Es (just common ones) - Withdrawal effects & management |
Common
- #1 sleepy, dry mouth, headache, weakness, constipation Withdrawal Rebound hypertension occurs 18-72hr after the last dose if stopped suddenly. There is headache, flushing, sweating, insomnia, agitation, tremor *Maintain through surgery using parenteral dosing prn * withdraw over at least 7/7 * BB may worsen withdrawal, stop BB several days before stopping Catapress |
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How does Catapress work for diagnosis of phaeochromocytoma?
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Measure plasma catecholamines before and 4-6hr after the dose. Catapress normally causes a fall in plasma NA by at least 50%. In phaeochromocytoma there is no fall or only a small reduction
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Drug interactions: Methyldopa (4)
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1. BP lowering agents
2. Iron: reduces absorption of methyldopa 3. TCA: reduce efficacy of methyldopa (&methyldopa causes depression) 4. Methyldopa increases effect of levodopa, monitor |
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Drug interactions - Clonidine
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1. lower BP
2. CNS depressants 3. TCA: reduce clonidine's effect 4. BB enhance withdrawal effect - stop before withdrawing clonidine; can rarely cause paradoxical hypertension when used together!! (titrate slow and monitor) |
