It’s time to dive back into pharmacology, so let’s learn about diltiazem using the Straight A Nursing pharmacology framework DRRUGS.
D: DRUG CLASS
Diltiazem is in the pharmacologic drug class of calcium channel blockers. CCBs inhibit calcium ions from entering the “slow channels” of vascular smooth muscle and the myocardium. The result is relaxation of vascular smooth muscle and dilation of coronary arteries. As vascular smooth muscle relaxes, it vasodilates, leading to lower blood pressure. Because CCBs also dilate the coronary arteries, they increase oxygen delivery to the heart. In addition, diltiazem decreases AV node conduction, which can slow the heart rate. You’ll see why this is useful later on when we talk about conditions diltiazem is used to treat.
Diltiazem is given via continuous IV infusion in the critical care setting and by mouth (PO). PO tablets are available as extended-release tablets and traditional tablets taken multiple times per day.
R: REGULAR DOSE RANGE
- For extended release tablets, a dose range of 180-240 mg is standard, though doses can be up to 360 mg daily.
- Immediate release tablet doses vary, but 30-120 mg 3 to 4 times per day is a standard dose range. If a patient is also taking simvastatin, the highest dose they should receive daily is 240 mg diltiazem.
- IV doses can be intermittent or continuous. An intermittent IV dose is 0.25 mg/kg, with continuous infusions running at 5-15 mg/hour for up to 24 hr.
Think about what the medication does and you can usually figure out what conditions it’s used to treat. Because diltiazem vasodilates the vascular smooth muscle, it is used in the treatment of hypertension. You’ll also see it used to treat and prevent angina or coronary artery spasm because of its effect on the coronary arteries (recall that it vasodilates these as well, which improves oxygen delivery to the heart muscle itself). Many times you’ll see diltiazem used as an antiarrhythmic, namely tachycardic dysrhythmias such as supraventricular tachycardia or atrial fibrillation/atrial flutter with rapid ventricular rates.
Diltiazem administration includes monitoring the patient’s blood pressure and heart rate before giving the dose and periodically throughout therapy. In addition, anyone receiving a continuous infusion should be on continuous ECG monitoring as bradycardia and severe hypotension can occur.
If your patient is taking diltiazem as a treatment or preventive medication for angina, then a focused but thorough angina assessment should be done. A great format to use is PQRST:
- P: PROVOCATION. What provokes the pain? Patients with stable angina will state that exercise or stress are the provocative factors, whereas patients with unstable angina will report that the pain can occur without provocation.
- Q: QUALITY. Ask the patient to describe the pain. Often angina pain is described as crushing, heaviness, squeezing.
- R: RADIATION. Determine if the patient’s pain radiates from the chest to another location. Common responses are pain that radiates to the jaw, left arm or even the back.
- S: SEVERITY. Ask the patient to rate the pain on a 0-10 scale. Patients with stable angina will typically report less severe pain than those who are experiencing unstable angina or myocardial infarction.
- T: TIME. Ask the patient how long the pain typically lasts. Stable angina typically lasts less than 20 minutes and is relieved by rest or medication. Unstable angina lasts longer than 20 minutes and often does not respond to medication.
Additionally, because diltiazem can cause patients to go into heart failure, you’ll want to closely monitor intake/output, lung sounds, oxygen saturation level, jugular venous distention, peripheral edema and daily weight.
Diltiazem should not be used in patients who have sick sinus syndrome, a 2nd or 3rd degree AV block, hypotension, current use of rifampin (a medication used to treat tuberculosis), pulmonary congestion, or a recent MI. It should be used with caution in elderly patients and those with severe liver or renal disease, ventricular arrhythmias or heart failure.
Also, make sure your patients know that grapefruit juice can increase the effects of the drug, so it’s best they avoid it while taking diltiazem.
S: SIDE EFFECTS
Diltiazem has a wide range of side effects. The most common is peripheral edema and the most concerning side effects are heart failure, arrhythmias and Stevens-Johnson Syndrome, which is a life-threatening rash. Of course, any medication that lowers blood pressure and delays AV node conduction can cause hypotension and bradycardia as well.
So there you have it, your quick guide to Diltiazem, a common calcium-channel blocker used to treat hypertension, angina and tachycardic arrhythmias.
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