Chapter 39: Antianginals and other Vasodilating Drugs
Terms
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- angina pectoris
- Literally means choking of the chest. It is the sensory response to a temporary insufficiency of oxygen (ischemia) in the heart.
- When does cardiac ischemia occur?
- Occurs when the demand of the myocardium is for oxygen exceeds the ability of the coronary vessels to supply oxygen.
- Compare the mechanism of action of nitrates given in low doses to nitrates given in high doses.
-
Low doses: Cause dilation of veins over arterioles, resulting in a pooling of blood in the periphery, which in turn reduces venous return to the heart, left en-diatolic pressure, and left end-diastolic volume (preload).
High doses: Dilate arteriolar tissue as well as venous smooth muscle. - Generally, how safe are nitrates?
- Long history of safety. They lack serious adverse effects.
- What is the preferred drug for rapid relief of the symptoms of angina pectoris? What route(s)are used and when will the onset of action occur?
-
Nitroglycerin.
Sublingual or buccal route. Onset of action occurs within 1-3 minutes. - What unusual drug form is also available for administering nitroglycerin sublingually?
- Aerosol form
- What two drug forms of nitroglycerin may be administered through the skin?
- Ointment or in a transdermal adhesive patch.
- What effect do nitrates have on blood pressure? When is this most noticeable?
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Hypotension.
When the patient assumes an upright position. -
What therapeutic measure may be the only action necessary to treat even the most severe
syncopal episodes for patients on nitroglycerin? - Positioning and other strategies that facilitate venous return to the heart.
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Describe a disturbing side effect that is present in about 50% of people receiving nitrates,
especially when initially started? - Flushing of the face and neck as well as a pounding headache.
- Identify four drugs that may enhance the hypotensive effects of nitrates.
- Alcohol, beta blockers, calcium channel blockers, and antidepressants.
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What is a significant problem with long-term repeated exposure to high dose nitrates?
Identify two possible strategies to minimize this problem. -
Leads to a decrease in the magnitude of most of the drug's effects, even if the dosage is progressively increased.
To minimize tolerance, nitrate therapy should be individualized by using the lowest effective dose and intermittent dosing schedule.
Drug holidays-brief periods of no therapy-may be sufficient to avoid the development of tolerance. - Identify two vital signs that should be taken before administering an antianginal drug and then again at the onset of drug action.
- BP and pulse
- Identify two proper places for buccal formulations.
-
Between the cheek and upper gum.
Between the lip and upper gum. - If angina persists, how many doses of nitroglycerin may be repeated before the patient should seek medical attention? Over what time period?
- 3 doses in 15 minutes
- Describe an appropriate area on the skin for applying a transdermal patch.
- Area that is clean and dry with little or no hair. Avoid scratches, scars, and areas of existing skin irritation.
- What should the nurse do if the patch loosens or falls off?
- Replace it with a new one.
- When are transdermal forms of nitroglycerin not used to treat angina?
- Acute attack of angina
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When applying nitroglycerin ointment what two precautions are taken to prevent exposing
yourself to the drug? - Use a small applicator (not your fingertips) and wear gloves.
-
What is recommended when oral and topical preparations of nitroglycerin are used
concurrently to minimize the possibility of additive hypotension and headache? - Stagger administration times.
- How long will sublingual nitroglycerin formulations remain effective when stored in the original container in a dark, cool, location?
- 5-6 months
- Name four factors that contribute to inactivation of sublingual nitroglycerin tablets?
- Light, heat, air, and moisture.
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What sensation has been used for years to indicate the freshness of sublingual nitroglycerin
tablets? What is the current thinking about this recommendation? - The tingling, burning sensation caused by the sublingual formulation was used as an indicator of the drug's freshness. This sign cannot be regarded as an indicator it will be effective.
- What may patients do to prevent introducing moisture in the container when removing sublingual nitroglycerin tablets?
- Replace the cap tightly and quickly each time the bottle is opened.