These drugs act on the central nervous system, decreasing the activity of the sympathetic nervous system. The end result is that blood vessels relax and blood pressure decreases.
Of the centrally-acting drugs, mainly reserpine, moxonidine and methyldopa are used in clinical practice.
This is an inexpensive drug that can be valuable in treating hypertension, especially in asthmatics who cannot take a beta blocker. In the past it was associated with various side-effects, including depression. The lower doses recommended now have fewer adverse effects, while providing good anti-hypertensive action. It can be used in uncomplicated hypertension.
Reserpine is contraindicated in patients with depression and must never be taken with alcohol. It may cause dizziness or drowsiness, headache and nasal congestion as well as other minor side-effects. When starting treatment with reserpine, patients must avoid driving or other activities requiring alertness.
In combinations: Protensin-M, Hygroton-Reserpine.
Methyldopa is specifically recommended for use in pregnancy and is rarely used in other circumstances.
It must never be used in patients with impaired liver or kidney function. This drug can have various side-effects, including drowsiness, dry mouth, depression and nightmares. Adverse mental effects can develop insidiously.
Tradenames: Aldomet, Hy-Po-Tone, Normopress, Sinepress.
In combination with diuretic: Aldoretic, Hydromet.
Similar to methyl dopa, but without the same degree of side effects. Useful in patients with metabolic syndrome and resistant hypertension.
Written by Dr Kathleen Coetzee, MBChB
Reviewed by Prof Brian Rayner, head of the Division of nefhrology and hypertension, University of Cape Town and Groote Schuur Academic Hospital, December 2010