Rifampin in CYP24A1-related Hypercalcemia and Hypercalciuria (RICHH)

  • End date
    Dec 10, 2030
  • participants needed
  • sponsor
    Children's Hospital of Philadelphia
Updated on 10 March 2022


This study evaluates the efficacy of rifampin in the treatment of hypercalcemia and/or hypercalciuria in participants with biallelic inactivating mutations of the CYP24A1 gene. Eligible subjects will receive rifampin for a total of 16 weeks during this study.


Idiopathic infantile hypercalcemia (IIH; omim 143880) is a genetic disorder of mineral metabolism characterized by severe hypercalcemia and/or hypercalciuria, suppressed serum levels of parathyroid hormone (PTH) and elevated levels of the active vitamin D metabolite, 1,25(OH)2D. Biallelic inactivating mutations of CYP24A1, the gene encoding the 24-hydroxylase enzyme that represents the principal pathway for inactivation of vitamin D metabolites, cause the most common and severe form of IIH.

Investigators have preliminary data supporting a novel therapeutic approach to repurpose rifampin as an agent to induce over-expression of CYP3A4, an enzyme that is expressed in the liver and intestine. When CYP3A4 is induced, the increased enzyme activity provides an alternative catabolic pathway for inactivation of vitamin D metabolites. The purpose of this study is to obtain support for an open label, escalating dose study to assess the effect, safety, and tolerability of once daily oral rifampin in participants with IIH due to inactivating mutations in CYP24A1.

In this study, Investigators will recruit 18 patients with biallelic inactivating mutations of CYP24A1. Participants will be observed for 8-weeks before a 16-week treatment phase of rifampin and 8 further weeks of observation. In addition to following the effect of treatment on calcium homeostasis, Investigators will also study the pharmacokinetics of rifampin in this condition and the effect on intestinal calcium absorption.

Condition Idiopathic Infantile Hypercalcaemia - Severe Form, Genetic Disease, Hypercalcemia, Idiopathic, of Infancy, Hypercalciuric Hypercalcemia, Idiopathic Infantile Hypercalcemia - Mild Form, Hypercalciuria
Treatment rifampin
Clinical Study IdentifierNCT03301038
SponsorChildren's Hospital of Philadelphia
Last Modified on10 March 2022


Yes No Not Sure

Inclusion Criteria

Males or females age 6 months to 65 years
at least one mutations of CYP24A1
Serum and/or urinary calcium above the normal reference range for age
Serum PTH concentration <20 pg/ml
Elevated or normal serum concentration of 1,25-dihydroxyvitamin D3

Exclusion Criteria

Parents/guardians or subjects who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures
Allergy to rifampin or related medications
Current therapies with medications that have significant drug-drug interactions with rifampin, defined as a medication considered to interact with CYP3A4 or CYP3A5 and either induce or inhibit expression or function of these P450 enzymes. By "drug-drug" interactions we are looking for medications that will affect metabolism or action of rifampin as exclusionary, not medications that will be affected by rifampin
Pregnancy or breastfeeding
Laboratory abnormalities that indicate clinically significant hepatic, or renal
Aspartate Aminotransferase (AST/SGOT) > 2.0 times the upper limit of normal Alanine
aminotransferase (ALT/SGPT) > 2.0 times the upper limit of normal Total bilirubin > 2.0
times the upper limit of normal Creatinine > 2.0 times the upper limit of normal
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