Peripherally Acting Antiadrenergic Agents
Overview
Overview
Peripherally acting antiadrenergic agents reduce sympathetic neurotransmission at adrenergic nerve terminals or deplete stored catecholamines. They are now used infrequently because safer and more predictable antihypertensive drugs are available.
Classification
Classification
The historical group includes reserpine, which blocks vesicular monoamine transport, and guanethidine, which enters adrenergic terminals and inhibits norepinephrine release. Adrenergic-neuron blockers are distinct from receptor antagonists.
Mechanism of action
Mechanism of action
Reserpine prevents vesicular storage and gradually depletes norepinephrine, dopamine and serotonin. Guanethidine is taken up by the neuronal norepinephrine transporter and suppresses transmitter release from peripheral sympathetic nerves.
Important members
Important members
Reserpine and guanethidine are the classic examples. Guanadrel and bethanidine are related older drugs with minimal contemporary use.
Clinical uses
Clinical uses
These drugs have historical importance in hypertension but little routine modern use. Reserpine may still appear in low-cost combinations in some settings, requiring careful assessment of adverse effects.
Adverse effects
Adverse effects
Marked postural hypotension, diarrhoea, nasal congestion, sexual dysfunction and fluid retention can occur. Reserpine may cause sedation, depression and parkinsonian symptoms because of central monoamine depletion.
Contraindications and precautions
Contraindications and precautions
Avoid reserpine in patients with active or previous severe depression and use caution in peptic ulcer disease and parkinsonism. Adrenergic-neuron blockers are hazardous in patients prone to orthostatic hypotension.
References
- National Institute of Diabetes and Digestive and Kidney Diseases. Reserpine. NCBI Bookshelf. Updated 2018. SOURCE:NCBI:RESERPINE:2018
- Farzam K, Kidron A, Lakhkar AD. Adrenergic Drugs. NCBI Bookshelf. Updated 2023. SOURCE:NCBI:ADR_DRUGS:2023