칼시트리올

비타민 D 유사체

칼시트리올은 비타민 D의 활성 호르몬 형태입니다. 수의학에서는 주로 **저칼슘혈증**(종종 부갑상선 기능 저하증에 속발함)을 관리하고 만성 신장 질환(CKD)에서 **속발성 부갑상선 기능 항진증**을 억제하는 데 사용됩니다. 또한 특정 견종의 원발성 특발성 지루증 치료에도 도움이 될 수 있습니다. > **임상 요점:** 건강한 동물의 신장은 1-알파-수산화효소를 생성하여 비활성 비타민 D를 활성 형태(칼시트리올)로 변환합니다. 만성 신부전에서는 기능적 신장 질량의 손실로 인해 이 효소가 결핍됩니다. 칼시트리올을 보충하면 이러한 대사 결함을 우회하여 부갑상선 호르몬(PTH) 합성을 직접적으로 억제하고 신장성 속발성 부갑상선 기능 항진증(신성 골이영양증)을 예방하거나 치료할 수 있습니다.

작용 기전: Calcitriol binds to the intracellular **Vitamin D Receptor (VDR)** in target tissues (intestine, bone, kidney, and parathyroid gland) to regulate calcium and phosphorus homeostasis. * **Intestine:** Upregulates the synthesis of calcium-binding proteins (e.g., calbindin) → significantly enhances the GI absorption of calcium and phosphorus. * **Kidney:** Promotes renal tubular reabsorption of calcium. * **Parathyroid Gland:** Directly binds to VDRs on the parathyroid gland → inhibits the transcription of the **PTH** gene, reducing PTH synthesis and secretion. * **Bone:** Works synergistically with PTH to stimulate osteoclast activity, mobilizing calcium and phosphorus into the extracellular fluid. Unlike other forms of vitamin D (like cholecalciferol or ergocalciferol), calcitriol does **not** require hepatic or renal activation, resulting in a rapid onset of action (approximately 1 day) and a short half-life.

동물 종별 용량

Cats

To suppress secondary hyperparathyroidism in CRF · 1.5-3.5 nanograms/kg PO daily given separately from meals (or 2.5-3.5 nanograms/kg PO once daily) · PO · q24h · Long-term · Remove oil from capsule, dilute in corn oil, then give the appropriate volume.
Long-term maintenance in animals with hypoparathyroidism · 0.03-0.06 micrograms/kg/day · PO · q24h · Long-term · Combine with oral calcium to reduce vitamin D dose requirements.

Dogs

To suppress secondary hyperparathyroidism in CRF · 2.5-3.5 nanograms/kg/day PO (Dogs with refractory hyperparathyroidism may require up to 6 nanograms/kg/day). Alternatively, pulsed-dosing: 20 nanograms/kg twice weekly PO at bedtime on an empty stomach. · PO · q24h or twice weekly · Long-term · Confirm CRF (creatinine >2 mg/dL) and reduce hyperphosphatemia to <6 mg/dL before starting.
Subacute and chronic maintenance treatment of hypocalcemia · Initially, 20-30 nanograms/kg/day PO divided twice a day for 3-4 days, then 5-15 nanograms/kg/day divided twice a day · PO · q12h · Initial 3-4 days, then maintenance
Long-term maintenance in animals with hypoparathyroidism · 0.03-0.06 micrograms/kg/day · PO · q24h · Long-term · Combine with oral calcium to reduce vitamin D dose requirements.
Primary idiopathic seborrhea (especially in spaniel breeds) · 10 nanograms/kg PO once daily · PO · q24h · Give as far away from the main meal as possible.

용량은 면허 수의 전문가를 위한 임상 참고 자료입니다. 항상 최신 라벨과 개별 환자에 대해 확인하십시오.

투여 경로

POInjectionTopical

금기

Hypercalcemia
Hyperphosphatemia (Calcium x Phosphorus product > 70)
Vitamin D toxicity
Malabsorption syndromes
Abnormal sensitivity to vitamin D effects

이상반응

Hypercalcemia
Hypercalciuria
Hyperphosphatemia
Polydipsia
Polyuria
Anorexia
Tissue mineralization (if given with hyperphosphatemia)

약물 상호작용

Calcium-containing phosphorus binding agents (e.g., calcium carbonate) · Use with calcitriol may induce hypercalcemia.
Corticosteroids · Can nullify the effects of vitamin D analogs.
Digoxin · Patients are highly sensitive to the arrhythmogenic effects of hypercalcemia; intensified monitoring is required.
Verapamil · Patients are sensitive to the effects of hypercalcemia; intensified monitoring is required.
Phenytoin, Barbiturates, Primidone · May induce hepatic enzyme systems and increase the metabolism of Vitamin D analogs, thus decreasing their activity.
Thiazide diuretics · May cause hypercalcemia when given in conjunction with Vitamin D analogs.

모니터링

Serum calcium (baseline, 1 week, then every 2-4 weeks/6 months depending on protocol)
Serum phosphorus
Serum creatinine
Serum PTH levels (especially in cats or refractory cases)
Clinical efficacy (improved appetite, activity level, slowed progression of disease)

과용량

Overdosage can cause **hypercalcemia**, **hypercalciuria**, and **hyperphosphatemia**. * **Acute Ingestion:** Manage using established protocols for GI decontamination. Orally administered mineral oil may reduce absorption and enhance fecal elimination. * **Chronic Overdosage:** Hypercalcemia secondary to chronic dosing should be treated by first temporarily discontinuing (not just dose reduction) calcitriol and exogenous calcium therapy. * **Severe Hypercalcemia:** May require treatment with furosemide, calcium-free IV fluids (e.g., normal saline), urine acidification, and corticosteroids.

VetSheet 약물 레퍼런스는 면허 수의 전문가를 위한 임상 의사결정 보조 도구이며, 전문적 판단이나 제조사의 최신 라벨을 대신하지 않습니다.