Effect of omeprazole on the pharmacokinetics of paricalcitol in healthy subjects

Proton Pump Inhibitors, Histamine-2 Receptor Antagonists, and Hip Fracture Risk among Patients on Hemodialysis

BACKGROUND AND OBJECTIVES

An association between proton pump inhibitor (PPI) use and hip fracture risk has been described in the general population, where the primary causative hypothesis focuses on impaired gastrointestinal calcium absorption. The impact of acid suppressor use on hip fracture risk in a high-risk subset, patients with ESKD requiring hemodialysis, is unknown and could help further distinguish the reason for higher susceptibility among PPI users.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using the US Renal Data System, we identified all hip fracture events recorded between 2009 and 2014 among patients dependent on hemodialysis. Eligible cases were matched on index date with ten controls. We identified PPI and histamine-2 receptor antagonist use from Medicare Part D claims covering 3 years before the index date and stratified according to proportion of days covered by filled prescriptions. Using logistic regression with multiple imputation for missing data, we estimated unadjusted and multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

We studied 4551 cases and 45,510 controls. Patients were older, more likely to be female and white, and had shorter dialysis vintage; fewer were obese. A larger proportion of patients had any prior PPI (70% versus 63%) or histamine-2 receptor antagonist (25% versus 23%) use. Use of PPI was associated with higher risk of hip fracture (adjusted OR, 1.19; 95% CI, 1.11 to 1.28). This association remained within subgroups of low, moderate, and high PPI use, yielding adjusted ORs of 1.16 (95% CI, 1.06 to 1.27), 1.21 (95% CI, 1.11 to 1.31), and 1.19 (95% CI, 1.08 to 1.31), respectively.

CONCLUSIONS

Among patients with ESKD on hemodialysis, PPIs and not histamine-2 receptor antagonists were associated with hip fracture events.

Sensitive method for the determination of paricalcitol by liquid chromatography and mass spectrometry and its application to a clinical pharmacokinetic study

A highly sensitive, specific and rapid LC-ESI-MS/MS method has been developed and validated for the quantification of paricalcitol (PAR) in human plasma (500 μL) using paricalcitol-d6 (PAR-d6 ) as an internal standard (IS) as per regulatory guidelines. A liquid-liquid extraction method was used to extract the analyte and IS from human plasma. Chromatography was achieved on Zorbax SB C18 column using an isocratic mobile phase in a gradient flow. The total chromatographic run time was 6.0 min and the elution of PAR and PAR-d6 occurred at ~2.6 min. A linear response function was established for the range of concentrations 10-500 pg/mL in human plasma. The intra- and inter-day accuracy and precision values for PAR met the acceptance criteria. The validated assay was applied to quantitate PAR concentrations in human plasma following oral administration of 4 µg capsules to humans.

Paricalcitol in secondary hyperparathyroidism and the survival benefit in patients with chronic kidney disease

Secondary hyperparathyroidism is a characteristic feature of chronic kidney disease, which develops early in the course of chronic kidney disease, often in a progressive way. It occurs as the renal function continues to decline and is encountered following a series of biochemical abnormalities, which are responsible for initiation and maintenance of increased parathyroid hormone (PTH) secretion. Several agents are used in the management of secondary hyperparathyroidism. Paricalcitol is a new generation selective vitamin D receptor activator that lowers PTH levels by exerting a less hypercalcaemic and hyperphosphataemic effect. In addition, there is emerging evidence of the benefit of paricalcitol in preventing intravascular calcification and proteinuria.