Vasodilator drugs

Erectile dysfunction is treated by local or systemic application of vasodilator drugs. The most effective is sildenafil, a phosphodiesterase-type 5 inhibitor. 

Discuss the general actions, uses, adverse reactions, contraindications, precautions, and interactions of antianginal and peripheral vasodilating drugs. 

Discuss important preadministration and ongoing assessment activities the nurse should perform on the patient taking an antianginal or peripheral vasodilating drug. 

Discuss ways to promote an optimal response to therapy, how to manage common adverse reactions, and important points to keep in mind when educating patients about the use of antianginal and peripheral vasodilating drugs. 

Vasodilating drags sometimes relieve die symptoms of vascular disease, but in some cases dragtherapy provides only minimal and temporary relief. Many of die vasodilating drug s are also used to treat hypertension. Their use as antihypertensives is discussed in Chapter 42. 

SUMMARY DRUG TABLE PER I PH ERAL VASODILATORS AN D MISCELLANEOUS VASODILATING DRUGS... 

Peripheral vasodilating drugs are chiefly used in the treatment of peripheral vascular diseases, such as arteriosclerosis obliterans, Raynaud s phenomenon, and spastic peripheral vascular disorders. Short-term use is rarely beneficial or permanent. Improvement, if it occurs, takes place gradually during weeks of therapy. 

Before administering the first dose of a peripheral vasodilating drug, Hie nurse obtains a thorough history of the patient s symptoms. The physical assessment is based on... 

Therapeutic results obtained from the administration of a peripheral vasodilating drug may not occur immediately. In some instances, results are minimal. The nurse assesses involved extremities daily for changes in color and temperature and records die patient s comments regarding relief from pain or discomfort. The nurse should monitor die blood pressure and pulse one to two times per day because tiiese dru may cause a decrease in blood pressure The anticipated result of tiierapy for cerebral vascular disease is an improvement in die patient s mental status. When die drug is taken for intermittent claudication, the nurse assesses the patient for increased walking distance without pain. 

Vasodilating drugs—for example, hydralazine (Apresoline) and minoxidil (Loniten)... 

ADMINISTERING VASODILATING DRUGS The nurse must carefully monitor the patient receiving minoxidil because the drug increases the heart rata The primary care provider is notified if any of the following occur ... 

Dogterom, P., Zbinden, G., and Reznik, G.K., Cardiotoxicity of vasodilators and positive inotropic/vasodilating drugs in dogs an overview, Crit. Rev. Toxicol., 22, 203,1992. 

Hydralazine is a vasodilating drug and inhibition of DNA methyltransferases in the range of 10-20 pM have been reported in vitro [83]. In addition, hypomethylation in cell culture has also been shovm [84]. Also the local anesthetic procaine [85] and its amide analog procainamide [84] have been identified as DNA methyltransferase inhibitors. Synthetic analogs of procaine have shown activity only around 500 pM [86] (Figure 8.10). 

These drugs are peripheral coronary vasodilating drugs with a-adrenoblocking activity that differ only in specificity to aj-adrenoreceptors. Unlike phenoxybenzamine and phentolamine (described above), they selectively block aj-receptors and have little affinity with Oj-adrenergic receptors. 

Gyceryl trinitrate is a vasodilator drug used for the relief of cardiac pain on exertion - angina pectoris. 

The reduction in plasma volume produced by p-blockers contrasts with the increased volume seen with other types of antihypertensives. Tolerance to the antihypertensive actions of p-blockers therefore is less of a problem than with the vasodilating drugs. An additional difference from the vasodilators is that plasma renin activity is reduced, rather than increased, by propranolol (Inderal). Orthostatic hypotension does not occur with p-blockers. 

Procaine is ineffective when administered through surface application, and is used only by injection. The onset of action for the drug is 2 to 5 minutes, and its duration of action is short. Vasoconstrictors are usually co-administered with this vasodilator drug to delay its absorption and to increase the duration of action. The drug is used for infiltration anesthesia, peripheral nerve block, and spinal anesthesia. 

When the diagnosis is correct and the drug is appropriate, an unsatisfactory therapeutic response can often be traced to compensatory mechanisms in the patient that respond to and oppose the beneficial effects of the drug. Compensatory increases in sympathetic nervous tone and fluid retention by the kidney, for example, can contribute to tolerance to antihypertensive effects of a vasodilator drug. In such cases, additional drugs may be required to achieve a useful therapeutic result. 

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