headache, dizziness, and orthostatic hypotension. The vasodilating effect of the drug
may be so sudden that circulating blood pools in vascular (vessel) beds. This may
cause the patient to become unconscious because of a lack of blood to the brain.
Falling to the floor in a faint allows the immediate return of that blood flow to the brain
and consciousness returns. Besides the sublingual form of nitroglycerin, sustained
release capsules (Nitro-Bid Plateau Caps) with 5 to 20 milligrams of drug taken daily in
divided doses, topical ointments (Nitrol, Nitro-Bid), and transdermal patches (Nitro-
Dur) are available. The ointment is applied using special paper every 6 hours. The
transdermal system patches are applied to the chest wall each morning and removed
after 12 hours. The patches offer the advantage of once daily dosing and less side
effects for the patient. Each of these dosage forms is used for the prevention of angina
attacks. Nitroglycerin sublingual tablets are volatile. They will lose their potency quickly
when they are incorrectly stored. Therefore, the tablets must be dispensed in their
original container (light-resistant container). The patient should also be instructed not to
remove the tablets from the original glass container (that is, to place the tablets in a
fancy pillbox). Federal law requires that all nitroglycerin products should be dispensed
in their original containers (that is, glass, light resistant, and not child-resistant
packaging). Another problem area with the nitroglycerin prescription is the dose.
Normally physicians prescribe them in grains using 1/100 grain, 1/150 grain, or 1/200-
grain tablets. We should be able to convert these to micrograms or milligrams.
Intravenous nitroglycerin is used in patients that present with unstable angina
(persisting chest pain) or possible myocardial infarction. The physician normally orders
the nitroglycerin as a drip (mcg/min) and titrates (adjusts) the dose to pain relief.
c. Isosorbide Dinitrate (Isordil, Sorbitrate). Isosorbide dinitrate is thought
to be effective in the prophylactic treatment of angina pectoris, as well as the treatment
of acute angina attacks. The side effects associated with this drug are headache and
dizziness. Isordil is supplied in many different dosage forms to include sublingual,
chewable, compressed, and sustained action tablets and capsules (Tembids). The
sublingual tablets are used in the acute angina attacks in a dose of from 2.5 to 10
milligrams. The usual oral dose is from 15 to 80 milligrams daily in divided doses.
These products should be dispensed in their original containers. Isosorbide
mononitrate (Ismo, Imdur) is another product often prescribed.
NOTE: Tolerance develops to nitrate products. For the agents to maintain
effectiveness, the patient must have a "nitrate-free" interval as part of the dosing
regimen. Nitroglycerin patches are generally applied in the morning and removed in the
evening (12-hours on/ 12-hours off); isosorbide products are administer in the morning,
usually at 7am or 8 am with the second dose 7 hours later (2pm-3pm). No additional
doses are administered so that the patient has a nitrate-free interval.
d. Hydralazine (Apresoline) and Minoxidil (Loniten). Hydralazine and
minoxidil are direct acting peripheral vasodilators used in the treatment of hypertension.
Hydralazine may be prescribed in combination with an oral nitrate in the treatment of
congestive heart failure. The addition of hydralazine further dilates peripheral vessels
and decreases workload on the heart.