Brand Name
Apo-Diltiaz
(CAN), Cardizem, Cardizem CD, Cardizem LA,
Cardizem
SR, Dilacor XR, Novo- Diltiazem (CAN), Nu-Diltiaz (CAN)
Class and
Category
Chemical
class: Benzothiazepine derivative
Therapeutic
class: Antianginal, antiarrhythmic, antihypertensive
Pregnancy
category: C
Indications
and Dosages
To treat
Prinzmetal’s (variant) angina and chronic stable angina
TABLETS
Adults and
adolescents. Initial: 30 mg t.i.d. or q.i.d. before meals and at bedtime, increased
every 1 or 2 days as appropriate. Maximum: 360 mg daily in divided doses
t.i.d. or q.i.d.
E.R.
TABLETS
Adults and
adolescents. Initial: 180 mg daily, increased every 7 to 14 days as needed. Maximum: 360
mg daily.
To control
hypertension
E.R.
CAPSULES
Adults and
adolescents. Initial: 180 to 240 mg daily, adjusted after 14 days as appropriate. Maximum:
360 mg daily.
S.R.
CAPSULES
Adults and
adolescents. Initial: 60 to 120 mg b.i.d., adjusted after 14 days as appropriate. Maximum:
360 mg daily.
TABLETS
Adults and
adolescents. Initial: 30 mg t.i.d. or q.i.d. before meals and at bedtime, increased
every 1 or 2 days as appropriate. Maximum: 360 mg daily in divided doses
t.i.d. or q.i.d.
E.R.
TABLETS
Adults. Initial: 180 to 240
mg daily, adjusted after 14 days, as needed. Maximum: 540 mg daily.
To treat atrial
fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia
I.V.
INFUSION OR INJECTION
Adults and
adolescents. 0.25 mg/kg given by bolus over 2 min. If response is inadequate after
15 min, 0.35 mg/kg given by bolus over 2 min. Then 10 mg/hr for continued reduction
of heart rate after bolus, increased by 5 mg/hr, as needed. Maximum: 15
mg/hr for up to 24 hr.
Mechanism of Action
Diltiazem inhibits calcium movement into
coronary and vascular smooth-muscle cells by blocking slow calcium channels in
cell membranes, as shown. This action decreases intracellular calcium, which:
• inhibits smooth-muscle cell
contractions
• decreases myocardial oxygen demand by
relaxing coronary and vascular smooth muscle, reducing peripheral vascular resistance
and systolic and diastolic blood pressures
• slows AV conduction time and prolongs
AV nodal refractoriness
• interrupts the reentry circuit in AV nodal
reentrant tachycardias.
Route Onset
Peak
Duration
P.O. 30–60
min In 2 wk Unknown
P.O. (E.R.) 2–3 hr In
2 wk Unknown
P.O. (S.R.) Unknown In
2 wk Unknown
I.V. In
3 min 2– 7 min 30min–10 hr
Incompatibilities
Don’t give diltiazem through same I.V.
line as acetazolamide, acyclovir, aminophylline, ampicillin sodium/sulbactam
sodium, cefamandole, cefoperazone, diazepam, furosemide, heparin,
hydrocortisone sodium succinate, methylprednisolone sodium succinate,
mezlocillin, nafcillin, phenytoin, rifampin, or sodium bicarbonate.
Contraindications
Acute MI; cardiogenic shock; Lown- Ganong-Levine
or Wolff-Parkinson-White syndrome, second- or third-degree AV block, and sick
sinus syndrome, unless artificial pacemaker is in place; pulmonary edema;
systolic blood pressure below 90 mm Hg; ventricular tachycardia (wide complex)
Interactions
DRUGS
anesthetic: Additive hypotension;
possibly decreased cardiac contractility, conductivity, and automaticity
benzodiazepines: Increased risk of
prolonged sedation
beta blockers: Possibly increased
risk of adverse cardiovascular effects
buspirone: Increased effects and
risk of buspirone toxicity
carbamazepine,
cyclosporine, lovastatin, quinidine, theophyllines: Decreased hepatic clearance
and increased serum levels of these drugs, leading to toxicity
cimetidine: Decreased diltiazem
metabolism, increased blood diltiazem level
digoxin: Increased blood
digoxin level
lithium:
Possibly
neurotoxicity
NSAIDs: Possibly
antagonized antihypertensive effect of diltiazem
prazocin: Possibly
increased risk of hypotension
procainamide:
Possibly increased risk of prolonged QT interval
quinidine:
Increased risk of adverse quinidine effects
rifampin: Decreased
blood diltiazem level to undetectable amounts
Adverse
Reactions
CNS: Abnormal
gait, amnesia, asthenia, depression, dizziness, dream disturbances, extrapyramidal
reactions, fatigue, hallucinations, headache, insomnia, nervousness, paresthesia,
personality change, somnolence, syncope, tremor, weakness
CV: Angina,
atrial flutter, AV block (first-, second-, and third-degree), bradycardia, bundle-branch
block, heart failure, hypotension, palpitations, peripheral edema, PVCs, sinus
arrest, sinus tachycardia, 12-lead ECG abnormalities, ventricular fibrillation,
ventricular tachycardia
EENT: Amblyopia,
dry mouth, epistaxis, eye irritation, gingival bleeding and hyperplasia, gingivitis,
nasal congestion, retinopathy, taste perversion, tinnitus
ENDO: Hyperglycemia
GI: Anorexia,
constipation, diarrhea, elevated liver function test results, indigestion, nausea,
thirst, vomiting
GU: Acute
renal failure, impotence, nocturia, polyuria, sexual dysfunction
HEME: Hemolytic
anemia, leukopenia, prolonged bleeding time, thrombocytopenia
MS: Arthralgia,
muscle spasms, myalgia
RESP: Cough,
dyspnea
SKIN: Alopecia,
diaphoresis, erythema multiforme, exfoliative dermatitis, flushing, leukocytoclastic
vasculitis, petechiae, photosensitivity, pruritus, purpura, rash, Stevens-Johnson
syndrome, toxic epidermal necrolysis, urticaria
Other: Angioedema,
hyperuricemia, weight gain
Nursing
Considerations
• Use diltiazem cautiously
in patients with impaired hepatic or renal function, and monitor liver and
renal function, as appropriate; drug is metabolized mainly in the liver and
excreted by the kidneys.
WARNING Monitor
patient’s blood pressure, pulse rate, and heart rate and rhythm by continuous
ECG as appropriate during therapy. Keep emergency equipment and drugs
available.
• Assess patient for signs
and symptoms of heart failure.
• If patient takes digoxin,
watch for digitalis toxicity (nausea, vomiting, halo vision, elevated serum digoxin
level).
• Administer sublingual
nitroglycerin, as prescribed, during diltiazem therapy.
• Expect to discontinue
drug if adverse skin reactions, usually transient, persist.
PATIENT
TEACHING
• Explain that regular
tablets can be crushed but that capsules and E.R. tablets must be swallowed
whole.
WARNING Tell
patient that stopping drug suddenly may have life-threatening effects.
• Advise patient to monitor
blood pressure and pulse rate regularly and to report significant changes to
prescriber.
• Urge patient to report
chest pain, difficulty breathing, dizziness, fainting, irregular heartbeat,
rash, or swollen ankles.
• Instruct patient to
maintain good oral hygiene, perform gum massage, and see a dentist every 6
months to prevent gingival bleeding and hyperplasia and gingivitis.
