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Generic name: paricalcitol (oral/injection) [ PAR-i-KAL-si-tol ]
Drug class: Vitamins

Medically reviewed by Philip Thornton, DipPharm. Last updated on Aug 23, 2023.

What is Zemplar?

Zemplar is a synthetic (man-made) form of vitamin D. Vitamin D is important for the absorption of calcium from the stomach and for the functioning of calcium in the body.

Zemplar is used to treat or prevent overactive parathyroid gland (hyperparathyroidism) in people with chronic kidney disease who are on dialysis.

Zemplar oral capsules are for use in adults and children at least 10 years old. The injection is for use in adults and children at least 5 years old.


You should not use Zemplar if you have high levels of calcium or vitamin D in your blood.

Before taking Zemplar, tell your doctor if you have high blood pressure, liver disease, or an electrolyte imbalance.

Do not take other vitamin or mineral supplements unless your doctor has told you to.

Avoid using calcium supplements or antacids without your doctor's advice. Use only the specific type of supplement or antacid your doctor recommends. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.

While using this medicine, you may need blood tests at your doctor's office. Visit your doctor regularly.

Seek emergency medical attention if you think you have used too much of this medicine. An overdose of vitamin D can cause serious or life-threatening side effects.

Overdose symptoms may include headache, weakness, drowsiness, dry mouth, nausea, vomiting, constipation, muscle or bone pain, metallic taste in the mouth, weight loss, itchy skin, changes in heart rate, loss of interest in sex, confusion, unusual thoughts or behavior, feeling unusually hot, severe pain in your upper stomach spreading to your back, or fainting.

Before taking this medicine

You should not use Zemplar if you are allergic to paricalcitol, or if you have high levels of vitamin D or calcium in your body.

You should not be treated with Zemplar injection if you have ever had a severe allergic reaction to it previously.

To make sure Zemplar is safe for you, tell your doctor if you have:

Tell your doctor if you are pregnant or breastfeeding.

If you breastfeed while receiving Zemplar injection, watch for signs of hypercalcemia in your baby (such as feeding problems, vomiting, constipation, or seizure).

How should I use Zemplar?

Take Zemplar exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Zemplar is usually given every other day or 3 times per week. Follow your doctor's instructions carefully.

Zemplar capsules are taken by mouth.

You may take the oral capsules with or without food.

Zemplar injection is given as an infusion into a vein during dialysis. A healthcare provider will give you this injection.

Tell your caregivers if you feel any burning, pain, or swelling when receiving the injection.

Your blood will need to be tested often. Your doses may be delayed based on the results.

Even if you have no symptoms, tests can help your doctor determine if this medicine is effective.

You may need to follow a special diet while using Zemplar. Follow all instructions of your doctor or dietitian. Learn about the foods to eat or avoid to help control your condition.

Store Zemplar oral capsules at room temperature away from moisture, light, and heat.

Dosing information

Usual Adult Dose for Secondary Hyperparathyroidism:

Initial dose: 0.04 to 0.1 mcg/kg (2.8 to 7 mcg), injected as a bolus dose through a hemodialysis vascular access port at any time during dialysis

Maximum frequency: Every other day

-Do not inject directly into a vein.

Use: Prevention and treatment of secondary hyperparathyroidism associated with chronic kidney disease Stage 5.
Initial dose:
Stage 3 or 4 Chronic Kidney Disease (CKD):
Initial dosing is based on baseline intact parathyroid hormone (iPTH):
-500 pg/mL or less: 1 mcg orally daily OR 2 mcg orally 3 times a week
-Over 500 pg/mL: 2 mcg orally daily OR 4 mcg orally 3 times a week

Stage 5 CKD:
Starting dose (micrograms) = baseline iPTH level (pg/mL)/80
Starting dose is given orally 3 times a week; only start if baseline serum calcium has been adjusted to 9.5 mg/dL or lower.

-If giving 3 times a week, do not give more often than every other day.

Use: Prevention and treatment of secondary hyperparathyroidism associated with:
-Chronic Kidney Disease (CKD) stages 3 and 4 (oral product only), or
-CKD stage 5 on hemodialysis or peritoneal dialysis (oral or injectable).

Usual Pediatric Dose for Secondary Hyperparathyroidism:

Safety and efficacy have not been established in pediatric patients.
The following is dosing used in a very small pediatric trial.
No data are available on children under 5 years old.

Initial dose, children 5 to 18 years:
0.04 mcg/kg three times per week if baseline intact parathyroid hormone (iPTH) is less than 500 pg/mL
0.08 mcg/kg three times per week if baseline iPTH is 500 pg/mL or higher
-Injected as a bolus dose through a hemodialysis vascular access port at any time during dialysis

Maximum frequency: Every other day

-Do not inject directly into a vein.

Use: Prevention and treatment of secondary hyperparathyroidism associated with chronic kidney disease Stage 5.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Because you will receive Zemplar injection in a clinical setting, you are not likely to miss a dose. Call your doctor for instructions if you miss a hemodialysis appointment.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using Zemplar?

Avoid using any vitamin D or calcium supplements without your doctor's advice.

If you take Zemplar oral: Ask your doctor before using an antacid, and use only the type your doctor recommends.

Grapefruit may interact with paricalcitol and lead to unwanted side effects. Avoid the use of grapefruit products.

Paricalcitol side effects

Get emergency medical help if you have signs of an allergic reaction to Zemplar: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

You may be more likely to have a broken bone if your parathyroid hormone levels get too low. Talk with your doctor about how to avoid the risk of fractures.

Common Zemplar side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Zemplar?

Some medicines can make paricalcitol much less effective when taken at the same time. If you take any of the following medicines, take your oral Zemplar dose 1 hour before or 4 to 6 hours after you take the other medicine:

Tell your doctor about all your current medicines. Many drugs can interact with paricalcitol, especially:

This list is not complete and many other drugs may interact with paricalcitol. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Zemplar only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.