Paricalcitol

Trade name Zemplar.

A drug used for the prevention and treatment of secondary hyperparathyroidism associated with chronic renal failure.

Is an analog of 1,25-dihydroxyergocalciferol, the active form of vitamin D2 (ergocalciferol).

US: C (Risk not ruled out).

Routes of administration oral, and Intravenous.

Bioavailability 72%.

Protein binding 99.8%.

Metabolism is hepatic.

Biological half-life 14-20 hours.

Excretion is by feces (74%), and urine (16%$.

Primary use in medicine is in the treatment of secondary hyperparathyroidism associated with chronic kidney disease.

Chronic renal failure patients treated with paricalcitol achieve a mean parathyroid hormone (PTH) reduction of 30% in six weeks. without incidence of hypercalcemia or hyperphosphatemia when compared to placebo.

A double-blind randomized trial in patients on dialysis showed a significant advantage over calcitriol.

After 18 weeks, all patients in the paricalcitol group had reached the target parathormone level of 100 to 300 pg/ml, versus none in the calcitriol group.

Paricalcitol and trandolapril has been found to reduce fibrosis in obstructive uropathy.

Common adverse reactions include: Nausea, diarrhea, edema, dizziness, GE reflux, hypercalcemia, hypocalcemia, hyperphosphatemia, rash.

Contraindicated with vitamin D toxicity, or impaired liver functions.

Calcium and phosphorus levels should be monitored regularly

Drugs that may interact with paricalcitol include: ketoconazole, digoxin, thiazides, magnesium-containing products, aluminum-containing products, drugs that interfere with the absorption of fat-soluble vitamins,

Overdoses can lead to hypercalcemia and hyperphosphataemiaare

Early symptoms of overdose can include:

Weakness

Headache

Somnolence

Nausea

Vomiting

Dry mouth

Constipation

Muscle pain

Bone pain

Metallic taste in the mouth.

Acts as an agonist at the vitamin D receptor and thereby lowers parathyroid hormone levels in the blood.

The plasma concentration of paricalcitol decreases rapidly within two hours after initial intravenous administration.

It is usually given no more frequently than every other day (3 times per week).

Dosage Forms & Strengths

injectable solution

2mcg/mL

5mcg/mL

capsule

1mcg

2mcg

4mcg

CKD stage 5

Indicated for prevention and treatment of secondary hyperparathyroidism associated with chronic kidney disease (CKD) stage 5 in patients on hemodialysis or peritoneal dialysis

Initial 0.04-0.1 mcg/kg IV 3 x/week, no more frequently than every other day.

Titrate up or down by 2-4 mcg q2-4Weeks.

Up to 0.24 mcg/kg PO have been administered

CKD stage 3 and 4

Indicated for prevention and treatment of secondary hyperparathyroidism associated CKD

PTH ≤500 pg/mL: 1 mcg PO qDay OR 2 mcg PO 3 times/week

PTH >500 pg/mL: 2 mcg PO qDay OR 4 mcg PO 3 times/week

Administer 3 times/week, no more frequently than every other day

Titrate dose based on response Monitoring

Serum PTH, calcium & phosphorus Monitoring parameters (Stage 5)

PTH same or increased: Increase dose

PTH level decreased by <30%: Increased dose

PTH level decreased by >30% & <60%: Maintain dose

PTH level decreased by >60%: Decrease dose

PTH level 1.5-3 x ULN: Maintain dose

Monitoring parameters (Stage 3 and 4)

Serum PTH at 2-4 week intervals

PTH same or increased: Increase by 1 mcg/day OR 2 mcg 3 times/week

PTH decreased <30%: Increase by 1 mcg/day OR 2 mcg 3 times/week

PTH decreased >30% or <60%: Maintain current dose

PTH decreased >60%: Decrease 1 mcg/day OR 2 mcg 3 times/week

PTH <60 pg/mL: Decrease 1 mcg/day OR 2 mcg 3 times/week