GENERAL DESCRIPTION
Vasodilators are the drugs that tend to dilates the (relax) smooth muscles of blood vessels. The smooth muscles of blood vessels is responsible for arteriolar and venous tone which in turn play important role role in myocardial wall stress. Arteriolar tone directly controls the peripheral vascular resistance and thus arterial pressure. Venous tone determines the capacity of the venous circulation an controls the amount of blood separated in the venous system versus the amount returned to the heart. Arteriolar tone is responsible for systolic wall stress while venous tone determines the diastolic wall stress.
Vasodilators dilates the arterial vessels and reduces the system vascular resistance and blood pressure while dilates the venous vessels and reduces venous blood pressure.
TYPES OF VASODILATORS
Vasodilators are generally classified on the basis of dilation of which types of blood vessels these drugs cause.
| Type | Generic Name | Brand Name |
| Venous Vasodilator
(Organic Nitrates) |
Nitroglycerin | Nitrostat, Nitro-bid, Nitro-quick |
| Amyl nitrite | Amyl nitrite | |
| Isosorbide di nitrate | Isordil | |
| Arterial Vasodilator | Hydralazine | Apresoline |
| Minoxidil | Loniten | |
| Diazoxide | Proglycem, Hyperstat IV, | |
| Mix vasodilator | Sodium Nitroprusside | Nitropress |
| Terazosin | Hytrin | |
| Prazosin | Minipress |
INDICATIONS
Hypertension
Angina Pectoris
Preeclampsia
Hypertensive emergencies
Heart failure
Pulmonary hypertension
Erectile dysfunction
Myocardial infarction
CONTRAINDICATIONS
Tachycardia
Heart failure
Constrictive pericarditis
Lupus
Aortic aneurysm
Porphyria
SIDE EFFECTS & ADVERSE EFFECTS
Flushing
Headache
Chronotropic
Ionotropic
Orthostatic hypotension
Syncope
Hypervolemia
Increase cardiac output
Tachycardia
DRUG INTERACTION
The concomitant use of hydralazine and epinephrine may cause tachycardia.
Oral indometacin eliminate the hypotensive effects of hydralazine
Hydralazine increase the plasma levels of beta blockers but has no clinical significance.
When hydralazine is given intravenously with Diazoxide may cause severe hypotension.
5 mg dose of Glibenclamide may reduce the hypotensive effects of minoxidil.
If minoxidil is taking with guanethidine, may cause severe hypotension and tachycardia.
Tropical minoxidil, hydralazine or nitrates absorption may increased three fold by the use of tropical tretinoin, dithranol.
Phosphodiesterase type-5 inhibitors potentiate the hypotensive effects of nitrates and may cause myocardial infarction. Therefore these drugs are contraindicated with nitrates.
Isosorbide dinitrate is contraindicated with other antimuscarinic drugs.
Glyceryl trinitrate infusion reduce the effects of heparin.
Levosimendan may cause severe hypotension when given with isosorbide mononitrate
Diazoxide cause hyperglycemia when given concurrently with other drugs with hyperglycemia effects e.g. corticosteroids, thiazides, chlorpromazine, and combined oral contraceptives.
Analgesic dose of aspirin increase plasma level of nitroglycerin given sublingually and may cause hypotension and headache.
NURSING INTERVENTIONS
Enquire the complete health history of the patient including allergy, drug interactions, and family background of hypertension.
Monitor blood pressure and pulse before and during treatment.
Check lab test for CBC, blood glucose, BUN, creatinine, platelets, electrolytes, LFT
Arterial pressure should be monitored during treatment via intra-arterial recording.
Hydralazine must be prescribed with meal.
Observe patients for possible s/s of edema or congestive heart failure.
PATIENT EDUCATION
Avoid taking alcohol while taking medicine.
Instruct the right dose and timings of medicine.
Advise patient to take hydralazine with meal.
Inform the patients about the possible side effects
Advice to take care and slow change of posture due to dizziness and danger of fall or injuries
Medicine may cause dizziness, don’t drive or perform alertness activities.
Inform patient minoxidil may cause increase in hair growths or thickness.
Report health professional immediately if dermatological adverse effects seen.
Do not breast feed while taking the medicine.
Educate patient healthy life style choice to reduce hypertension such as dietary intake of sodium and cholesterol, exercise, smoking cessation etc.