Version May 2024
Note: KDIGO guidelines do not recommend routine use of vitamin D analogs in patients not on dialysis with chronic kidney disease (CKD) stages G3 to G5; it may be reasonable to reserve use for patients with CKD stages G4 or G5 and with severe and progressive hyperparathyroidism. Caution is advised to avoid hypercalcemia or elevated phosphate levels (Ref). Do not initiate in patients with serum calcium at the ULN (eg, >9.5 mg/dL) (Ref).
Secondary hyperparathyroidism in patients with chronic kidney disease on dialysis:
IV: Initial: 0.04 to 0.1 mcg/kg (2.8 to 7 mcg) given no more frequently than every other day at any time during dialysis; adjust dose based on serum intact PTH (iPTH) goal of 2 to 9 times the ULN for the assay used (Ref), as follows:
iPTH above target and increased: Increase by 2 to 4 mcg every 2 to 4 weeks; maximum dose: 0.24 mcg/kg/day.
iPTH above target and decreased by <30%: Increase by 2 to 4 mcg every 2 to 4 weeks; maximum dose: 0.24 mcg/kg/day.
iPTH above target and decreased by 30% to 60%: Maintain paricalcitol dose.
iPTH above target and decreased by >60%: Decrease paricalcitol dose based on clinical judgement.
iPTH at target and stable: Maintain paricalcitol dose.
Note: Dose suspension may be necessary due to persistent and abnormally low iPTH (goal iPTH 2 to 9 times the ULN for the assay used (Ref)) to reduce risk of adynamic bone disease or serum calcium persistently above normal; restart therapy at a reduced dose after iPTH and/or serum calcium has normalized.
Conversion to IV paricalcitol from IV calcitriol: A conversion ratio of paricalcitol to calcitriol of approximately 3:1 or 4:1 may be used (Ref).
Oral: Initial dose is calculated, in mcg, based on baseline iPTH level divided by 80 and administered 3 times weekly, no more frequently than every other day. Note: To reduce the risk of hypercalcemia initiate only after baseline serum calcium has been adjusted to ≤9.5 mg/dL.
Dose titration:
Titration dose (mcg) = Most recent iPTH level (pg/mL) divided by 80
Note: In situations where monitoring of iPTH, calcium, and phosphorus occurs less frequently than once per week, a more modest initial and dose titration rate may be warranted:
Modest titration dose (mcg) = Most recent iPTH level (pg/mL) divided by 100
Dosage adjustment for elevated serum calcium: Decrease dose by 2 to 4 mcg.
Secondary hyperparathyroidism associated with stage 3 and 4 CKD:
Initial dose based on baseline serum iPTH:
iPTH ≤500 pg/mL: Oral: 1 mcg once daily or 2 mcg 3 times/week.
iPTH >500 pg/mL: Oral: 2 mcg once daily or 4 mcg 3 times/week.
Dosage adjustment based on iPTH level relative to baseline, adjust dose at 2- to 4-week intervals:
iPTH same or increased: Oral: Increase paricalcitol dose by 1 mcg once daily or 2 mcg 3 times/week.
iPTH decreased by <30%: Oral: Increase paricalcitol dose by 1 mcg once daily or 2 mcg 3 times/week.
iPTH decreased by ≥30% and ≤60%: Oral: Maintain paricalcitol dose.
iPTH decreased by >60%: Oral: Decrease paricalcitol dose by 1 mcg once daily* or 2 mcg 3 times/week.
iPTH <60 pg/mL: Oral: Decrease paricalcitol dose by 1 mcg once daily* or 2 mcg 3 times/week.
*If patient is taking 1 mcg once daily and further dose reduction is needed, decrease to 1 mcg 3 times/week. If further dose reduction is required, withhold therapy as needed and restart at a lower dosing frequency.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
No dosage adjustment necessary.
Mild to moderate impairment: No dosage adjustment necessary.
Severe impairment: There are no dosage adjustments provided in the manufacturer’s labeling (has not been studied).
Refer to adult dosing. Use with caution and initiate at the lower end of the dosage range.
(For additional information see "Paricalcitol: Pediatric drug information")
Note: KDIGO guidelines suggest that in children vitamin D analogs may be considered to maintain serum calcium levels in an age-appropriate normal range, which differs from recommendation in adult patients (Ref).
Secondary hyperparathyroidism associated with stage 5 chronic renal failure (CKD):
Oral:
Children ≥10 years and Adolescents ≤16 years:
Initial dose: Calculate based on intact parathyroid hormone (iPTH) serum levels using the following equation. Round the calculated dose down to the nearest whole number and administer calculated dose 3 times/week and no more frequently than every other day.
Initial dose (mcg) = baseline iPTH (pg/ml) divided by 120.
Titration: Every 4 weeks, may increase dose by 1 mcg/dose (eg, increase from 1 mcg 3 times/week to 2 mcg 3 times/week) to maintain iPTH within target range. Based on response and clinical markers (iPTH, serum Ca, and P), each administered dose may be decreased 2 mcg/dose at any time. If dosage reduction is required while receiving 1 or 2 mcg 3 times/week, discontinue therapy and resume when appropriate.
Adolescents ≥17 years: Note: To reduce the risk of hypercalcemia, initiate only after baseline serum calcium has been adjusted to ≤9.5 mg/dL. In patients where laboratory markers are monitored less frequently than once weekly, more modest dosing should be used.
Initial dose: Calculate based on iPTH serum levels using the following equation and administer calculated dose 3 times/week and no more frequently than every other day.
Initial dose (mcg) = baseline iPTH (pg/mL) divided by 80.
Titration : Adjust mcg dose based on at least weekly labs (iPTH, Ca, and P); administer calculated dose 3 times/week and not more often than every other day.
iPTH level (pg/mL) based: Dose (mcg) = Most recent iPTH level (pg/mL) divided by 80.
Elevated serum calcium: Decrease dose by 2 to 4 mcg.
For modest dosing adjustments: In situations where monitoring of iPTH, calcium, and phosphorus occurs less frequently than once per week, a more modest initial and dose titration rate may be warranted. Calculate based on iPTH serum levels using the following equation and administer calculated dose 3 times/week and no more frequently than every other day.
Modest dose (mcg) = Most recent iPTH level (pg/mL) divided by 100.
Parenteral: Children ≥5 years and Adolescents: IV through HD access (not directly into vein):
Initial: Dose based on baseline serum iPTH; administer 3 times weekly at any time during dialysis session, and no more frequently than every other day:
iPTH <500 pg/mL: 0.04 mcg/kg/dose.
iPTH ≥500 pg/mL: 0.08 mcg/kg/dose.
Dosing adjustment: Prior to any paricalcitol dosing adjustments, ensure serum Ca is within normal limits. The dose of paricalcitol should be adjusted based on iPTH levels relative to baseline and targets as follows:
Above target and iPTH level decreased by <30%: Increase paricalcitol dose by 0.04 mcg/kg/dose every 2 to 4 weeks.
iPTH level ≥150 pg/mL and decreased by ≥30% to ≤60%: Maintain current paricalcitol dose.
iPTH level <150 pg/mL or decreased by >60%: Decrease weekly paricalcitol dose by 0.04 mcg/kg or by 50% if decreased dose is zero.
Secondary hyperparathyroidism associated with stage 3 and 4 chronic renal failure (CKD):
Children ≥10 years and Adolescents ≤16 years: Oral: Initial: 1 mcg 3 times/week no more frequently than every other day; may titrate every 4 weeks; increase dose by 1 mcg (eg, increase from 1 mcg 3 times/week to 2 mcg 3 times/week) to maintain iPTH within target range. Based on response and clinical markers (iPTH, serum Ca, and P), each administered dose may be decreased by 1 mcg at any time. If dosage reduction is required while receiving 1 mcg 3 times/week, discontinue therapy, resuming when appropriate.
Adolescents ≥17 years: Note: If using 3 times/week dosing, doses should not be administered more frequently than every other day:
Initial: Dose based on baseline serum iPTH: Oral:
iPTH ≤500 pg/mL: 1 mcg once daily or 2 mcg 3 times/week.
iPTH >500 pg/mL: 2 mcg once daily or 4 mcg 3 times/week.
Titration and dosage adjustment: May adjust at 2- to 4-week intervals based on iPTH level relative to baseline:
iPTH same or increased: Increase paricalcitol dose by 1 mcg once daily or 2 mcg 3 times/week.
iPTH decreased by <30%: Increase paricalcitol dose by 1 mcg once daily or 2 mcg 3 times/week.
iPTH decreased by ≥30% and ≤60%: Maintain paricalcitol dose.
iPTH decreased by >60%: Decrease paricalcitol dose by 1 mcg/day or 2 mcg 3 times/week (see Note).
iPTH <60 pg/mL: Decrease paricalcitol dose by 1 mcg/day or 2 mcg 3 times/week (see Note).
Note: If patient is taking the lowest dose (1 mcg) on the daily regimen and an additional dose reduction is necessary, then regimen should be changed to 1 mcg 3 times weekly. If further reduction is required, withhold drug as needed and restart at a lower dose.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
All patients: No adjustment necessary; paricalcitol indicated for use in chronic kidney disease stages 3 through 5.
Adjustment not needed for mild-to-moderate impairment. Paricalcitol has not been evaluated in severe hepatic impairment.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. As reported in adults, unless otherwise noted.
>10%:
Gastrointestinal: Nausea (children, adolescents, and adults: 6% to 13%)
Respiratory: Rhinitis (children and adolescents: 17%)
1% to 10%:
Cardiovascular: Atrial flutter (<2%), cardiac arrhythmia (<2%), chest discomfort (<2%), chest pain (≤3%), edema (6% to 7%), hypertension (≤7%), hypotension (≤5%), palpitations (3%), peripheral edema (3%), syncope (≤3%)
Dermatologic: Acne vulgaris (<2%), alopecia (<2%), burning sensation of skin (<2%), dermal ulcer (3%), night sweats (<2%), pruritic rash (<2%), pruritus (<2%), skin blister (<2%), skin rash (4%), urticaria (<2%)
Endocrine & metabolic: Dehydration (3%), hirsutism (<2%), hypercalcemia (<2%), hyperkalemia (<2%), hyperphosphatemia (<2%), hypervolemia (5%), hypocalcemia (<2%), hypoglycemia (3%), hypoparathyroidism (<2%), increased thirst (<2%), weight loss (<2%)
Gastrointestinal: Abdominal distress (≤4%), constipation (children, adolescents, and adults: ≤5%), decreased appetite (<2%), diarrhea (≤7%), dysgeusia (<2%), dysphagia (<2%), gastritis (<2%), gastroesophageal reflux disease (<2%), gastrointestinal hemorrhage (5%), ischemic bowel disease (<2%), peritonitis (5%), rectal hemorrhage (<2%), vomiting (children, adolescents, and adults: ≤8%), xerostomia (≤3%)
Genitourinary: Erectile dysfunction (<2%), malignant neoplasm of breast (<2%), mastalgia (<2%), urinary tract infection (3%), urinary urgency (children and adolescents: 6%), vaginal infection (<2%)
Hematologic & oncologic: Anemia (<2%), lymphadenopathy (<2%), prolonged bleeding time (<2%)
Hepatic: Abnormal hepatic function tests (<2%), increased serum aspartate aminotransferase (<2%)
Hypersensitivity: Hypersensitivity reaction (6%)
Infection: Fungal infection (3%), infection (3%), sepsis (5%)
Local: Pain at injection site (<2%)
Nervous system: Abnormal gait (<2%), agitation (<2%), anxiety (3%), asthenia (<2%), cerebrovascular accident (<2%), chills (5%), confusion (<2%), delirium (<2%), depression (3%), dizziness (≤7%), fatigue (≤3%), headache (children, adolescents, and adults: ≤5%), hypoesthesia (<2%), insomnia (≤5%), malaise (3%), myoclonus (<2%), nervousness (<2%), pain (<2%), paresthesia (<2%), restlessness (<2%), unresponsive to stimuli (<2%), vertigo (5%)
Neuromuscular & skeletal: Arthralgia (5%), arthritis (5%), back pain (3%), joint stiffness (<2%), muscle spasm (3%), muscle twitching (<2%), myalgia (<2%)
Ophthalmic: Conjunctivitis (children and adolescents: 6%; adults: <2%), glaucoma (<2%), ocular hyperemia (<2%)
Otic: Otalgia (<2%)
Renal: Chronic renal failure (3%)
Respiratory: Asthma (children and adolescents: 6%), cough (≤3%), dyspnea (<2%), nasopharyngitis (≤8%), oropharyngeal pain (4%), orthopnea (<2%), pneumonia (5%), pulmonary edema (<2%), sinusitis (3%), upper respiratory tract infection (<2%), wheezing (<2%)
Miscellaneous: Fever (5%), swelling (<2%)
Frequency not defined: Gastrointestinal: Abdominal pain (children and adolescents)
Postmarketing:
Hypersensitivity: Angioedema (including laryngeal edema)
Renal: Increased serum creatinine
Hypersensitivity to paricalcitol or any component of the formulation; vitamin D toxicity; hypercalcemia
Concerns related to adverse effects:
• Excessive vitamin D: Excessive vitamin D administration may lead to over suppression of PTH, progressive or acute hypercalcemia, hypercalciuria, hyperphosphatemia, and adynamic bone disease.
• Hypercalcemia: Progressive and/or acute hypercalcemia may increase risk of cardiac arrhythmias and seizures; chronic hypercalcemia may lead to generalized vascular and other soft-tissue calcification, exacerbate nephrolithiasis, and has been associated with increased mortality in adults with chronic kidney disease (CKD) (KDIGO 2017). High intake of calcium and phosphate with vitamin D (and its derivatives) may increase risk of hypercalciuria and hyperphosphatemia. Risk of hypercalcemia may be increased by concomitant use of calcium-containing supplements, other vitamin D compounds, and/or medications that increase serum calcium (eg, thiazide diuretics). Monitor serum calcium frequently in high-risk patients.
Some dosage forms may contain propylene glycol; in neonates large amounts of propylene glycol delivered orally, intravenously (eg, >3,000 mg/day), or topically have been associated with potentially fatal toxicities which can include metabolic acidosis, seizures, renal failure, and CNS depression; toxicities have also been reported in children and adults including hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Shehab 2009).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, Oral:
Zemplar: 1 mcg, 2 mcg [contains alcohol, usp]
Generic: 1 mcg, 2 mcg, 4 mcg
Solution, Intravenous:
Zemplar: 2 mcg/mL (1 mL); 5 mcg/mL (1 mL, 2 mL) [contains alcohol, usp, propylene glycol]
Generic: 2 mcg/mL (1 mL); 5 mcg/mL (1 mL, 2 mL)
Yes
Capsules (Paricalcitol Oral)
1 mcg (per each): $8.00 - $11.09
2 mcg (per each): $17.73 - $22.18
4 mcg (per each): $24.53 - $44.36
Capsules (Zemplar Oral)
1 mcg (per each): $15.61
2 mcg (per each): $31.22
Solution (Paricalcitol Intravenous)
2 mcg/mL (per mL): $4.80 - $5.85
5 mcg/mL (per mL): $12.00 - $14.25
Solution (Zemplar Intravenous)
2 mcg/mL (per mL): $7.27
5 mcg/mL (per mL): $18.18
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, Oral:
Zemplar: 1 mcg, 2 mcg, 4 mcg [contains alcohol, usp]
Oral: Administer with or without food. With the 3 times/week dosing schedule, doses should not be given more frequently than every other day.
IV: Administer as a bolus dose at any time during dialysis. May be administered through a hemodialysis vascular access port or intravenously if an access port is unavailable. Doses should not be administered more often than every other day.
Oral: May be administered with or without food. With the 3 times/week dosing schedule, doses should not be given more frequently than every other day.
Parenteral: Administer undiluted as an IV bolus through hemodialysis port at any time during dialysis. Doses should not be administered more often than every other day.
IV: Prevention and treatment of secondary hyperparathyroidism in adults and pediatric patients 5 years and older with chronic kidney disease (CKD) on dialysis
Oral: Prevention and treatment in adults and pediatric patients 10 years and older with secondary hyperparathyroidism associated with stage 3 and 4 CKD and stage 5 CKD patients on hemodialysis or peritoneal dialysis
Paricalcitol may be confused with calcifediol, calcitriol
Zemplar may be confused with zaleplon, Zelapar, Zemuron, zolpidem, ZyPREXA Zydis
Substrate of CYP3A4 (major); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.
Aluminum Hydroxide: Vitamin D Analogs may increase the serum concentration of Aluminum Hydroxide. Specifically, the absorption of aluminum may be increased, leading to increased serum aluminum concentrations. Management: Consider avoiding chronic use of aluminum and aluminum-containing products in patients who are also taking active vitamin D analogs. If coadministered, monitor aluminum status and for signs and symptoms of aluminum-related toxicities. Risk D: Consider therapy modification
Bile Acid Sequestrants: May decrease the serum concentration of Vitamin D Analogs. More specifically, bile acid sequestrants may impair absorption of Vitamin D Analogs. Management: Avoid concomitant administration of vitamin D analogs and bile acid sequestrants (eg, cholestyramine). Separate administration of these agents by several hours to minimize the potential risk of interaction. Monitor plasma calcium concentrations. Risk D: Consider therapy modification
Burosumab: Vitamin D Analogs may enhance the adverse/toxic effect of Burosumab. Risk X: Avoid combination
Calcium Salts: May enhance the adverse/toxic effect of Vitamin D Analogs. Risk C: Monitor therapy
Clofazimine: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
CYP3A4 Inhibitors (Strong): May increase the serum concentration of Paricalcitol. Risk C: Monitor therapy
Danazol: May enhance the hypercalcemic effect of Vitamin D Analogs. Risk C: Monitor therapy
Digoxin: Paricalcitol may enhance the adverse/toxic effect of Digoxin. Risk C: Monitor therapy
Erdafitinib: Serum Phosphate Level-Altering Agents may diminish the therapeutic effect of Erdafitinib. Management: Avoid coadministration of serum phosphate level-altering agents with erdafitinib before initial dose increase period based on serum phosphate levels (Days 14 to 21). Risk D: Consider therapy modification
Fexinidazole: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Risk X: Avoid combination
Fusidic Acid (Systemic): May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Risk X: Avoid combination
Mineral Oil: May decrease the serum concentration of Vitamin D Analogs. More specifically, mineral oil may interfere with the absorption of Vitamin D Analogs. Management: Avoid concomitant, oral administration of mineral oil and vitamin D analogs. Consider separating the administration of these agents by several hours to minimize the risk of interaction. Monitor plasma calcium concentrations. Risk D: Consider therapy modification
Multivitamins/Fluoride (with ADE): May enhance the adverse/toxic effect of Vitamin D Analogs. Risk X: Avoid combination
Multivitamins/Minerals (with ADEK, Folate, Iron): May enhance the adverse/toxic effect of Vitamin D Analogs. Risk X: Avoid combination
Orlistat: May decrease the absorption of Vitamins (Fat Soluble). Management: Administer oral fat soluble vitamins at least 2 hours before or 2 hours after the administration of orlistat. Avoid concomitant administration due to the risk of impaired vitamin absorption. Risk D: Consider therapy modification
Sucralfate: Vitamin D Analogs may increase the serum concentration of Sucralfate. Specifically, the absorption of aluminum from sucralfate may be increased, leading to an increase in the serum aluminum concentration. Management: Consider avoiding chronic use of aluminum and aluminum-containing products, such as sucralfate, in patients who are also taking active vitamin D analogs. If combined, monitor for signs and symptoms of aluminum-related toxicities. Risk D: Consider therapy modification
Thiazide and Thiazide-Like Diuretics: May enhance the hypercalcemic effect of Vitamin D Analogs. Risk C: Monitor therapy
Vitamin D Analogs: May enhance the adverse/toxic effect of other Vitamin D Analogs. Risk X: Avoid combination
Adverse events have been observed in some animal reproduction studies.
It is not known if paricalcitol is present in breast milk.
According to the manufacturer, the decision to continue or discontinue breastfeeding during therapy should take into account the risk of infant exposure, the benefits of breastfeeding to the infant, and benefits of treatment to the mother. Monitor breastfed infants for signs and symptoms of hypercalcemia.
Some products may contain coconut or palm kernel oil.
Signs and symptoms of vitamin D intoxication and hypercalcemia.
Serum calcium and phosphorus:
IV: Serum calcium twice weekly during initial phase, then at least monthly once dose established
Oral: Serum calcium and phosphorus at baseline, at least every 2 weeks for initial 3 months or following dose adjustment, then monthly for 3 months, then every 3 months
Serum or plasma intact PTH (iPTH):
IV: Every 2 to 4 weeks during initial phase or after dose adjustment
Oral: Baseline, at least every 2 weeks for 3 months or following dose adjustment, then monthly for 3 months, then every 3 months
KDIGO guidelines (2017):
Serum calcium, phosphorus, and parathyroid hormone (PTH): Frequency of measurement may be dependent upon the presence and magnitude of abnormalities, the rate of progression of chronic kidney disease (CKD), and the use of treatments for chronic kidney disease-mineral and bone disorder (CKD-MBD) (KDIGO 2017):
CKD stage G3a to G3b: Serum calcium and phosphate: Every 6 to 12 months; PTH: Frequency based on baseline level and progression of CKD
CKD stage G4: Serum calcium and phosphate: Every 3 to 6 months; PTH: Every 6 to 12 months
CKD stage G5 and G5D: Serum calcium and phosphate: Every 1 to 3 months; PTH: Every 3 to 6 months
Note: Due to the complexity and interdependency of the laboratory parameters used for therapeutic decisions in chronic kidney disease-mineral and bone disorder (CKD-MBD) patients, serial assessments of phosphate, calcium, and parathyroid hormone (PTH) levels should be considered together (KDIGO 2017). Asymptomatic hypocalcemia is acceptable in patients with CKD stage 3 to 5 (KDIGO 2017).
Calcium (total): Adults: Normal range: 8.5 to 10.5 mg/dL (2.12 to 2.62 mmol/L) (IOM 2011). Avoid hypercalcemia for CKD stages G3a to G5D; asymptomatic hypocalcemia may not require correction (KDIGO 2017).
Phosphorus: 2.5 to 4.5 mg/dL (0.81 to 1.45 mmol/L). Lower elevated phosphorus levels toward the normal range for CKD stages G3a to G5D (KDIGO 2017).
PTH:
CKD stage G3a to G5: Optimal PTH level is unknown; evaluate patients with progressively elevated intact PTH levels or if levels are consistently above the normal range (assay-dependent) (KDIGO 2017).
Dialysis patients: Maintain iPTH within 2 to 9 times the upper limit of normal for the assay used (KDIGO 2017).
Decreased renal conversion of vitamin D to its primary active metabolite (1,25-hydroxyvitamin D) in chronic renal failure leads to reduced activation of vitamin D receptor (VDR), which subsequently removes inhibitory suppression of parathyroid hormone (PTH) release; increased serum PTH (secondary hyperparathyroidism) reduces calcium excretion and enhances bone resorption. Paricalcitol is a synthetic vitamin D analog which binds to and activates the VDR in kidney, parathyroid gland, intestine and bone, thus reducing PTH levels and improving calcium and phosphate homeostasis.
Distribution: Vd:
Healthy subjects: Oral: 34 L; IV: 24 L
Stage 3 and 4 CKD: Oral: 44 to 46 L
Stage 5 CKD: Oral: 38 to 49 L; IV: 31 to 35 L
Protein binding: >99%
Metabolism: Hydroxylation and glucuronidation via hepatic and nonhepatic enzymes, including CYP24, CYP3A4, UGT1A4; forms metabolites (at least one active)
Bioavailability: Oral: 72% to 86% in healthy subjects
Half-life elimination:
Healthy subjects: Oral: 4 to 6 hours; IV: 5 to 7 hours
Stage 3 and 4 CKD: Oral: 17 to 20 hours
Stage 5 CKD (on HD or PD): Oral: 14 to 18 hours; IV: 14 to 15 hours
Time to peak, plasma: 3 hours: Delayed by food
Excretion: Healthy subjects: Feces (oral: 70%; IV: 63%); urine (oral: 18%, IV: 19%); 51% to 59% as metabolites
Altered kidney function: Compared with healthy subjects, chronic kidney disease subjects on dialysis showed a decreased clearance and increased half-life.
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