Intravenous Secondary hyperparathyroidism in patients with chronic kidney disease on dialysis
Adult: Initial dose is based on baseline iPTH level taken 3 times wkly every other day via bolus inj at any time during dialysis. Max: 40 mcg. Dose must be titrated based on iPTH level relative to baseline, serum Ca and phosphorus levels at 2-4 wk intervals. If iPTH is the same as baseline, increased, or decreased by <30%: Increase initial dose by 2-4 mcg. If iPTH decreased by ≥30% and ≤60%: Maintain initial dose. If iPTH is <150 pg/mL or decreased by >60%: Decrease initial dose by 2-4 mcg.
Oral Secondary hyperparathyroidism in chronic kidney disease
Adult: Stages 3-4: Initial dose is based on baseline intact parathyroid hormone (iPTH) levels. iPTH: ≤500 pg/mL: 1 mcg once daily or 2 mcg 3 times wkly every other day; >500 pg/mL: 2 mcg once daily or 4 mcg 3 times wkly every other day. Dose must be titrated based on iPTH level relative to baseline, serum Ca and phosphorus levels at 2-4 wk intervals. If iPTH decreased by <30%: Increase initial dose by 1 mcg (if taken daily) or 2 mcg (if taken 3 times wkly every other day). If iPTH decreased by ≥30% and ≤60%: Maintain initial dose. If iPTH is <60 pg/mL or decreased by >60%: Decrease initial dose by 1 mcg (if taken daily) or 2 mcg (if taken 3 times wkly every other day). Stage 5 on dialysis: Initial dose is based on baseline iPTH level (pg/mL) taken 3 times wkly every other day. Max: 32 mcg. Dose titration is individualised based on iPTH, serum Ca and phosphorus levels.
Monitor for signs and symptoms of vit D toxicity and hypercalcaemia. Oral: Monitor serum or plasma iPTH; and serum Ca and phosphorus during the initial dosing or following dose titrations at least every 2 wk for 3 mth, then mthly for 3 mths, and every 3 mth thereafter. IV: Monitor serum or plasma iPTH every 2-4 wk, then every 3 mth once dose is established. Monitor serum Ca and phosphorus 2 times wkly during initial phase, then at least mthly once dose is established.
Symptoms: Hypercalcaemia (manifesting as weakness, anorexia, nausea, vomiting, constipation, increased thirst and urination, wt loss), hypercalciuria, hyperphosphataemia, PTH oversuppression. Management: Supportive treatment. Monitor serum electrolytes (esp Ca), rate of urinary Ca excretion, and ECG (esp patients on digitalis). General treatment for hypercalcaemia requires discontinuation of Ca supplements, institution of low Ca diet, attention to fluid and electrolyte imbalances, and patient mobilisation. If ingestion is recent, employ gastric lavage or induce emesis.
Paracalcitol may cause hypercalcaemia which may potentiate digitalis toxicity. Increased risk of hypercalcaemia w/ thiazide diuretics, Ca and phosphate-containing drugs, and other vit D-related drugs. Increased AUC and mean half-life w/ ketoconazole. May cause bone toxicity w/ Al-containing preparations (e.g. phosphate binders, antacids) and hypermagnesaemia w/ Mg-containing preparations (e.g. antacids). Oral absorption may be impaired by cholestyramine and mineral oil.
Description: Mechanism of Action: Paricalcitol is a synthetic vit D analogue which selectively activates vit D receptors (VDR) in the kidneys, parathyroid gland, bones, and intestines. This reduces PTH levels by inhibiting PTH synthesis and secretion, and improves Ca and phosphate homeostasis. Pharmacokinetics: Absorption: Bioavailability: 72-86%. Time to peak plasma concentration: 3 hr. Distribution: Volume of distribution: Oral: 34 L (healthy); 44-46 L (stage 3-4 CKD); 38-49 L (stage 5 CKD); IV: 24 L (healthy); 31-35 L (stage 5 CKD). Plasma protein binding: >99%. Metabolism: Extensively metabolised via hydroxylation and glucuronidation by hepatic and nonhepatic enzymes (e.g. CYP24, CYP3A4, UGT1A4). Excretion: Via faeces (oral: 70%; IV: 63%) and urine (oral: 18%; IV: 19%). Elimination half-life: Oral: 4-6 hr (healthy); 17-20 hr (stage 3-4 CKD); 14-18 hr (stage 5 CKD); IV: 5-7 hr (healthy); 14-15 hr (stage 5 CKD).
H05BX02 - paricalcitol ; Belongs to the class of other anti-parathyroid agents. Used in the management of calcium homeostasis.
Anon. Paricalcitol. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 05/04/2017.Anon. Paricalcitol. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 05/04/2017.Buckingham R (ed). Vitamin D Substances. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/04/2017.Joint Formulary Committee. Paricalcitol. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/04/2017.Paricalcitol Capsule (Bionpharma Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 05/04/2017.Paricalcitol Injection (Amneal Biosciences). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 05/04/2017.