Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CINACALCET HYDROCHLORIDE vs CRYSTODIGIN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Allosteric activator of the calcium-sensing receptor (Ca SR) on parathyroid chief cells, increasing sensitivity to extracellular calcium and reducing parathyroid hormone (PTH) secretion.
Cardiac glycoside that inhibits the Na+/K+-ATPase pump, leading to increased intracellular sodium, which in turn promotes calcium influx via the Na+/Ca2+ exchanger, resulting in increased myocardial contractility (positive inotropy). It also has negative chronotropic and dromotropic effects via vagomimetic action.
Secondary hyperparathyroidism in patients with chronic kidney disease on dialysis,Hypercalcemia in patients with parathyroid carcinoma,Severe hypercalcemia in patients with primary hyperparathyroidism who are unable to undergo parathyroidectomy
Treatment of heart failure with reduced ejection fraction (FDA-approved),Control of ventricular response in atrial fibrillation and atrial flutter (FDA-approved)
30 mg orally once daily, titrate every 2-4 weeks to a maximum of 180 mg once daily to achieve target intact parathyroid hormone (i PTH) level.
0.5 mg intravenously over 2-4 hours, then 0.25 mg every 6 hours as needed up to a total of 1.5 mg in 24 hours.
Terminal elimination half-life: 30–40 hours in patients with normal renal function; prolonged to 42–83 hours in moderate to severe hepatic impairment. Steady-state reached within 7 days.
Terminal elimination half-life approximately 1.6–1.9 days (38–45 hours) in patients with normal renal function; prolonged in renal impairment.
Hepatic via CYP3A4, CYP2D6, and CYP1A2; major metabolites are inactive.
Primarily renal excretion; minimal hepatic metabolism. Not significantly metabolized by cytochrome P450 enzymes.
Renal: 80% (as metabolites), Fecal: 15%, Biliary: negligible.
Primarily renal excretion of unchanged drug; ~80-90% eliminated in urine, ~10-20% in feces via biliary excretion.
97% bound to albumin.
~20–25% bound to plasma proteins, primarily albumin.
Approximately 1.7 L/kg (1000 L for 70 kg person), indicating extensive tissue distribution.
Vd approximately 5–10 L/kg, indicating extensive tissue distribution; clinical significance: large Vd means low plasma concentration relative to total body load, necessitating loading doses.
76–82% (oral); food increases AUC by 50–80%.
Oral: 60–80% (variable, depends on formulation and gastrointestinal factors); Intravenous: 100%.
No dose adjustment required for any degree of renal impairment, including end-stage renal disease (ESRD) on dialysis.
Cr Cl 10-50 m L/min: reduce dose by 25-50%; Cr Cl <10 m L/min: reduce dose by 50-75% or use alternative.
Mild hepatic impairment (Child-Pugh A): no dose adjustment. Moderate to severe hepatic impairment (Child-Pugh B or C): reduce starting dose to 30 mg daily and monitor i PTH and serum calcium closely.
Child-Pugh class B: reduce dose by 50%; Child-Pugh class C: avoid use.
Not established for pediatric patients; safety and efficacy in children have not been determined.
Loading dose: 10-20 mcg/kg intravenously over 2-4 hours; maintenance: 5-10 mcg/kg every 6 hours as needed.
No specific dose adjustment recommended; clinical studies included patients aged 65 and older, but no overall differences in safety or efficacy were observed. Use with caution due to potential for increased sensitivity.
Start at lower end of dosing range (0.25 mg intravenously), adjust based on renal function and response, monitor for toxicity.
None.
None.
Hypocalcemia: Can cause life-threatening hypocalcemia; monitor serum calcium levels frequently.,Seizures: Increased risk, especially in patients with history of seizure disorder.,QT interval prolongation: Hypocalcemia may exacerbate QT prolongation; monitor ECGs in patients with risk factors.,Hypotension and worsening heart failure: Cases reported, especially in patients with impaired cardiac function.,Adynamic bone disease: May develop with oversuppression of PTH; monitor bone-specific alkaline phosphatase.
Narrow therapeutic index; toxicity can be life-threatening.,Hypokalemia, hypomagnesemia, and hypercalcemia increase risk of digoxin toxicity.,Electrolyte monitoring and dose adjustment in renal impairment.,Patients with acute myocardial infarction, myocarditis, or severe pulmonary disease may be at increased risk of arrhythmias.
Hypocalcemia,Known hypersensitivity to cinacalcet or any component of the formulation
Ventricular fibrillation,Known hypersensitivity to digoxin or other digitalis glycosides,Hypercalcemia,Hypokalemia (uncorrected),Atrioventricular block (second- or third-degree) unless a pacemaker is present,Hypertrophic obstructive cardiomyopathy (relative contraindication)
Take with food or immediately after a dialysis treatment. Avoid high-calcium meals (e.g., dairy) within 2 hours of dosing as calcium binds cinacalcet and reduces absorption. No other dietary restrictions; maintain consistent calcium intake per renal diet.
Avoid high-fiber foods and large amounts of bran or pectin, as they may reduce absorption. Grapefruit juice may increase blood levels; limit consumption. Consistent dietary potassium intake is important; extremes (high or low) can affect drug action.
FDA Pregnancy Category C. No adequate studies in pregnant women. In animal studies, cinacalcet produced fetal toxicity (reduced fetal weight, increased incidence of skeletal variations) at doses 0.5-4 times the maximum human dose. Risk cannot be ruled out. Use only if potential benefit justifies potential risk to fetus.
Pregnancy Category C. First trimester: Association with fetal cardiac glycoside toxicity and malformations in animal studies; limited human data. Second trimester: Potential for fetal bradycardia and hypoxia due to placental transfer. Third trimester: Risk of neonatal digitalis toxicity, including arrhythmias and heart block.
No data on presence in human milk. In lactating rats, cinacalcet was excreted in milk with milk:plasma ratio approximately 2.4. Potential for serious adverse reactions in nursing infants; decision to discontinue nursing or drug should consider importance of drug to mother.
Excreted in breast milk in low concentrations (M/P ratio approximately 0.75-1.0). Considered compatible with breastfeeding; monitor infant for signs of toxicity (bradycardia, vomiting).
No specific dosing adjustments are established due to lack of pharmacokinetic data in pregnancy. Serum calcium and PTH should be monitored frequently to guide dosing, as volume distribution and clearance may change. Generally, maintain lowest effective dose to control hyperparathyroidism.
Increased volume of distribution and renal clearance in second and third trimesters may necessitate dose increases. Monitor serum digoxin levels and adjust to maintain therapeutic range (0.5-1.0 ng/m L).
Monitor serum calcium within 1 week of initiation or dose adjustment; cinacalcet may cause hypocalcemia, so do not start if calcium <8.4 mg/d L. Correct elevated PTH in CKD patients with i PTH >300 pg/m L on dialysis; not for use in non-dialysis CKD. QTc prolongation risk: obtain baseline ECG and monitor electrolytes, especially if on QT-prolonging drugs. Nausea and vomiting are common; administer with food or after dialysis session to improve tolerance.
Crystodigin (digitoxin) has a very long half-life (~5-7 days) requiring careful monitoring to avoid accumulation. Unlike digoxin, it is primarily hepatically metabolized, so renal impairment has less impact on dosing. Always check for drug interactions with CYP3A4 inducers/inhibitors. Therapeutic monitoring of serum levels is essential (target 15-25 ng/m L).
Take cinacalcet with food or right after a dialysis session to reduce stomach upset.,Do not stop taking this medication suddenly; consult your doctor if you have side effects.,Report symptoms of low calcium such as muscle cramps, numbness, or tingling in fingers/toes.,Tell your doctor if you have a history of seizures or liver problems.,Avoid taking strong CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) unless prescribed; inform all healthcare providers.
Take exactly as prescribed; do not miss doses or double up.,Report any symptoms of toxicity: nausea, vomiting, visual disturbances (yellow-green halos), or irregular heartbeat.,Avoid over-the-counter medications without consulting your doctor, especially antacids and laxatives.,Keep regular appointments for blood tests to monitor drug levels and kidney function.,Do not stop suddenly; withdrawal can worsen heart condition.
"Cinacalcet, a potent CYP3A4 inhibitor, significantly decreases the metabolism of Indinavir, a CYP3A4 substrate. This leads to elevated plasma concentrations of Indinavir, increasing the risk of dose-related toxicities such as nephrolithiasis, acute interstitial nephritis, and hepatotoxicity. The interaction may require Indinavir dose reduction and close monitoring for adverse effects."
"Duloxetine, a moderate inhibitor of CYP2D6 and CYP1A2, can reduce the metabolism of cinacalcet, a CYP2D6 and CYP1A2 substrate, leading to increased plasma concentrations of cinacalcet. This elevation may enhance the pharmacodynamic effects of cinacalcet, including a greater reduction in parathyroid hormone (PTH) and increased risk of hypocalcemia. Clinically, patients may experience symptoms such as paresthesias, muscle cramps, or cardiac arrhythmias due to electrolyte disturbances."
"Nitrofural, an antibacterial agent, is a potent inhibitor of CYP450 enzymes, particularly CYP3A4 and CYP1A2. Cinacalcet is extensively metabolized by CYP3A4 and, to a lesser extent, CYP1A2. Concomitant use of Nitrofural with Cinacalcet significantly reduces the systemic clearance of Cinacalcet, leading to elevated plasma concentrations. This increases the risk of dose-dependent adverse effects such as hypocalcemia, QT prolongation, and seizures."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CINACALCET HYDROCHLORIDE vs CRYSTODIGIN, answered by our medical review team.
CINACALCET HYDROCHLORIDE is a Calcimimetic that works by Allosteric activator of the calcium-sensing receptor (Ca SR) on parathyroid chief cells, increasing sensitivity to extracellular calcium and reducing parathyroid hormone (PTH) secretion.. CRYSTODIGIN is a Cardiac Glycoside that works by Cardiac glycoside that inhibits the Na+/K+-ATPase pump, leading to increased intracellular sodium, which in turn promotes calcium influx via the Na+/Ca2+ exchanger, resulting in increased myocardial contractility (positive inotropy). It also has negative chronotropic and dromotropic effects via vagomimetic action.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CINACALCET HYDROCHLORIDE and CRYSTODIGIN depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CINACALCET HYDROCHLORIDE is: 30 mg orally once daily, titrate every 2-4 weeks to a maximum of 180 mg once daily to achieve target intact parathyroid hormone (i PTH) level.. The standard adult dose of CRYSTODIGIN is: 0.5 mg intravenously over 2-4 hours, then 0.25 mg every 6 hours as needed up to a total of 1.5 mg in 24 hours.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between CINACALCET HYDROCHLORIDE and CRYSTODIGIN in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. CINACALCET HYDROCHLORIDE is classified as Category C. FDA Pregnancy Category C. No adequate studies in pregnant women. In animal studies, cinacalcet produced fetal toxicity (reduced fetal weight, increased incidence of skeletal variat. CRYSTODIGIN is classified as Category C. Pregnancy Category C. First trimester: Association with fetal cardiac glycoside toxicity and malformations in animal studies; limited human data. Second trimester: Potential for fe. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.