ZEMPLAR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZEMPLAR (ZEMPLAR).
Vitamin D receptor agonist; binds to vitamin D receptors, regulating gene expression of calcium-binding proteins and cellular proliferation/differentiation.
| Metabolism | Metabolized primarily by hepatic enzymes, including CYP24A1 and CYP3A4. |
| Excretion | Primarily hepatobiliary (74% of absorbed dose recovered in feces as parent drug and metabolites); renal excretion accounts for approximately 16% (primarily as metabolites). |
| Half-life | Terminal elimination half-life is 5–7 hours in healthy subjects; prolonged to 14–21 hours in patients with chronic kidney disease stage 5 on hemodialysis, reflecting reduced clearance. |
| Protein binding | >99.8% bound to plasma proteins, primarily to vitamin D-binding protein (DBP) and albumin. |
| Volume of Distribution | 0.3–0.5 L/kg, indicating distribution primarily into extracellular fluid; no extensive tissue binding. |
| Bioavailability | Oral: approximately 95% for the intravenous formulation; the oral capsule has a bioavailability of about 70% due to first-pass metabolism. |
| Onset of Action | Intravenous: 1–2 weeks for reduction of serum PTH in dialysis patients; Oral: 2–4 weeks for suppression of PTH. |
| Duration of Action | Intravenous: Single dose suppresses PTH for at least 24 hours; Oral: Duration of effect is 24–48 hours with repeated dosing. Continued suppression requires maintenance therapy. |
| Molecular Weight | 416.6 |
0.04-0.1 mcg/kg IV three times weekly; titrate to serum calcium. Oral: 1-2 mcg daily or 0.5-1 mcg three times weekly.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for any degree of renal impairment, but monitor calcium and phosphate. |
| Liver impairment | No specific guidelines; use caution in severe hepatic impairment. |
| Pediatric use | IV: 0.04-0.1 mcg/kg three times weekly. Oral: not established for pediatric use. |
| Geriatric use | No specific adjustments; start at lower end of dosing range due to potential age-related decreased renal function. |
| 1st trimester | Zemplar (paricalcitol) is a vitamin D analog. Human data on use in the first trimester are limited. Animal studies have shown fetotoxicity at doses higher than human therapeutic doses. Use only if clearly needed and potential benefit outweighs risk. |
| 2nd trimester | Limited human data; animal studies show fetotoxicity at high doses. May cause hypercalcemia in the fetus. Use if benefit outweighs risk. |
| 3rd trimester | Use with caution; may cause fetal hypercalcemia, parathyroid suppression, and potential teratogenic effects. Monitor maternal and fetal calcium levels. |
Clinical note
Comprehensive clinical and safety monograph for ZEMPLAR (ZEMPLAR).
| Placental transfer | Analogous to vitamin D; crosses placenta. In animals, radiolabeled paricalcitol crosses placenta. |
| Breastfeeding | Excretion into human milk is unknown; other vitamin D analogs are excreted. Consider risk of hypercalcemia in the infant. Avoid breastfeeding or use with caution, monitor infant serum calcium. |
■ FDA Black Box Warning
Not applicable; no FDA black box warning for Zemplar.
| Serious Effects |
Hypersensitivity to paricalcitol or any componentHypercalcemiaVitamin D toxicity
| Precautions | Hypercalcemia, Hyperphosphatemia, Adynamic bone disease, Digitalis toxicity risk if hypercalcemia occurs, Monitor serum calcium and phosphate levels |
| Food/Dietary | Limit high-calcium foods (e.g., dairy, fortified cereals) and high-phosphorus foods (e.g., nuts, seeds, cola, processed meats) as directed by your healthcare provider. Do not consume phosphate binders (e.g., calcium acetate, sevelamer) simultaneously; separate by at least 1 hour. |
| Clinical Pearls |
Loading safety data…
| Lactation Rating | L4 (Limited Data - Possibly Hazardous) |
| Teratogenic Risk | Zemplar (paricalcitol) is a vitamin D analog. Limited human data in pregnancy; animal studies show fetal toxicity at high doses. First trimester: possible association with vitamin D analog effects - theoretical risk of fetal hypercalcemia. Second and third trimesters: potential for fetal hypercalcemia and nephrocalcinosis if maternal serum calcium is elevated. Avoid unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal serum calcium, phosphorus, and intact PTH levels. Fetal monitoring: ultrasound for growth restriction and nephrocalcinosis if prolonged use. Monitor for maternal hypercalcemia. |
| Fertility Effects | No specific human data on fertility effects. Vitamin D analogs may affect calcium homeostasis and potentially impact reproductive function indirectly. Animal studies did not show impaired fertility at clinically relevant doses. |
| ZEMPLAR (paricalcitol) is a vitamin D analog used to manage secondary hyperparathyroidism in chronic kidney disease (CKD). Monitor serum calcium, phosphorus, and intact PTH regularly. Do not co-administer with phosphate binders containing magnesium or aluminum due to risk of increased absorption and toxicity. Start at 0.04-0.1 mcg/kg IV or 1-2 mcg PO. Titrate based on PTH, calcium, and phosphorus levels. If calcium x phosphorus product > 55 mg²/dL², hold or reduce dose. Use with caution in liver impairment. |
| Patient Advice | Take ZEMPLAR exactly as prescribed, not more or less often. · Do not take phosphate binders containing magnesium or aluminum (e.g., Maalox, Mylanta) within 1 hour of taking ZEMPLAR. · Adhere to prescribed dietary restrictions, especially limiting foods high in calcium and phosphorus. · Report symptoms of high calcium (e.g., nausea, vomiting, constipation, weakness, confusion) or low phosphorus (e.g., bone pain, fatigue). · Keep all lab appointments to monitor calcium, phosphorus, and PTH levels. |