Many vasodilators have been used in peripheral vascular diseases (PVDs) like Buerger’s, Raynaud’s, diabetic vascular insufficiency, gangrene, ischaemic leg ulcers, frost bite and cerebrovascular inadequacy.
DRUGS FOR PERIPHERAL VASCULAR
DISEASES
Many vasodilators have
been used in peripheral vascular diseases (PVDs) like Buerger’s, Raynaud’s,
diabetic vascular insufficiency, gangrene, ischaemic leg ulcers, frost bite and
cerebrovascular inadequacy.
Cyclandelate
It is a papaverine
like general smooth muscle relaxant which
increases cutaneous, skeletal muscle and cranial blood flow in normal
individuals. However, efficacy in PVDs is not different from placebo. Side
effects are flushing, palpitation and headache.
Dose: 200–400 mg TDS; CYCLOSPASMOL, CYCLASYN 200, 400 mg tab/cap.
Xanthinol nicotinate (Nicotinyl xanthinate)
It is a compound of xanthine and nicotinic acid,
both of which are vasodilators. It increases blood flow in many vascular beds
and has been promoted for cerebrovascular disorders and PVDs, but therapeutic benefits
are insignificant.
Dose: 300–600 mg TDS oral;
300 mg by i.m. or slow i.v. injection;
COMPLAMINA
150 mg tab, 500 mg retard tab, 300 mg/2 ml inj.
Pentoxiphylline
(Oxpentifylline)
An analogue of
theophylline and a phosphodiesterase inhibitor, it has been shown to increase
blood flow in ischaemic areas by reducing whole blood viscosity and by
improving flexibility of RBCs. The rheological
(dealing with property of flow) action rather than vasodilatation is said to be
responsible for improving passage of blood through microcirculation. Thus,
there are no chances of the ‘steal’ phenomenon. Oral doses do not affect heart
rate, t.p.r. or BP.
Pentoxiphylline is
usually well tolerated: side effects are nausea, vomiting, dyspepsia and
bloating which can be minimized by taking the drug after meals.
Dose: 400 mg BD–TDS; TRENTAL400, FLEXITAL
400 mg SR tab, 300 mg/15
ml for slow i.v. injection.
Indications are:
· Nonhaemorrhagic stroke: claimed to hasten
recovery.
· Chronic cerebrovascular insufficiency: to improve
symptoms like vertigo, tinnitus, memory defects, low drive.
·
Transient ischaemic attacks (TIAs).
· Intermittent claudication due to arteriosclerotic,
diabetic or inflammatory vascular disease: walking distance is increased.
· Trophic leg ulcers, gangrene.
It has been shown to
improve sperm motility—tried in male factor infertility.
Despite initial encouraging reports, the overall benefits of
this drug are modest and restricted to a fraction of patients.
Comment Apart from the above drugs, β adrenergic agonists like
isoxsuprine, CCBs like nifedipine and α blockers like prazosin, tolazoline,
phenoxybenzamine have been used in PVDs. However, no vasodilator can overcome
organic obstruction. Because ischaemia itself is the most potent vasodilator
stimulus in skeletal muscle and cerebral beds, vasodilators can even divert the
blood to non-ischaemic areas (steal phenomenon). They obviously are more useful
when vasospasm is wholely or partly involved, e.g. in Raynaud’s phenomenon. PGI2
has been employed in severe cases with rest pain. Antioxidants like vit. E,
ginkgo biloba and antiplatelet drugs are the other measures, but overall
benefits are inconsistent, mostly marginal.
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