The Effects of Potassium Citrate on Bone Metabolism

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00357331
Recruitment Status : Completed
First Posted : July 27, 2006
Results First Posted : June 12, 2017
Last Update Posted : June 12, 2017
Information provided by (Responsible Party):
Weill Medical College of Cornell University

Brief Summary:

Skeletal buffering of chronic acid loads may contribute to a significant amount of bone loss over time. Evidence from a few small short-term studies suggests that basic compounds, namely potassium citrate and potassium bicarbonate may reduce bone loss and improve bone density.

The purpose of this study is to evaluate the effects of potassium citrate on bone metabolism. We hypothesize that administration of potassium citrate to postmenopausal women with osteopenia will reduce bone resorption and improve bone mineral density.

Postmenopausal women with osteopenia (T score between -1.0 and -2.5) and no history of fracture will be randomized to either daily potassium citrate or placebo for one year. Primary outcomes will be markers of bone turnover, which will be measured over 12 months. Secondary outcomes will be bone mineral density, compliance, and adverse events.

Condition or disease Intervention/treatment Phase
Bone Diseases, Metabolic Osteoporosis, Postmenopausal Drug: potassium citrate Phase 4

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Detailed Description:

Participants were recruited from a single academic center. Subjects underwent screening at the Clinical Translational Science Center (CTSC) at Weill Cornell Medical College (WCMC). Study visits occurred at the CTSC where investigators administered and monitored questionnaires, compliance, adverse events, and endpoint measurements. Subjects were assigned an anonymous study number at the beginning of the trial, which was used to track the participant's data throughout the study. The protocol was approved by the Institutional Review Board (IRB) and the procedures followed were in accordance with the ethical standards of the IRB and the CTSC. All patients provided informed consent.

Treatment Groups Participants were assigned to either the treatment or placebo group using a randomization schema generated by the statistician. The randomization method was blocked randomization with a blocking factor of 4. The blocked randomization was not stratified by any other factors. The study was conducted in a double blind manner. The study medication, K-citrate, or placebo, was dispensed through the New York Presbyterian Hospital (NYPH) pharmacy. Bottles in the pharmacy were sequentially numbered and the number was linked to the blocked randomization scheme. Only the statistician and the pharmacist knew the meaning of the numbered codes and only the statistician knew the blocking assignment. Blocked randomization with balanced randomization of each block and blocks of the same size was performed by the RANDOM procedure within the WinPepi Version 11.1.

Investigators who administered questionnaires and assessed compliance, adverse effects or endpoint information were blind to group assignment. Only study investigators were able to enroll participants in the study and assign them to treatment arms. Those assigned to the treatment group received the study drug (40 mEq daily K Citrate: two 10 mEq tablets twice daily); those assigned to the control group received inert tablets of the same quantity. All participants received daily supplementation with Citracal (630 mg calcium citrate and 400 IU vitamin D3 per two caplets). All supplements and medications were provided by Mission Pharmacal/Bayer Pharmaceuticals in Boerne, Texas. Subjects discontinued their prior supplements at the time of entry to the study and were advised to adhere to the standardized supplementation regimen outlined by the protocol.

Measurements and Outcomes Subjects were evaluated at baseline, 1, 3, 6, and 12 months. The following outcomes were measured: change in bone turnover markers including u-NTX, BSAP, OC and P1NP; changes in 24 hour urinary concentrations of citrate, sulfate, and calcium; and changes in BMD measured from baseline to 12 months. Adverse events and compliance were measured at each visit over the study duration. Adverse events pertained to medication side effects, including, but not limited to, gastrointestinal complaints, nausea, diarrhea, and stomach pain, as well as the development of hyperkalemia or metabolic acidosis. If any of the following occurred, potassium exceeded 5.2 mmol/L; bicarbonate level exceeded 32 mmol/L; creatinine increased by more than 30% or rose above 2.0 ng/dL; or GFR was < 60, study medications were stopped until the parameter normalized, at which point the medication was resumed at half dose: Compliance was assessed by remaining pill count; good compliance was defined at ≤ 20% of pills remaining, or ≤ 18 pills remaining for each 3-month dose allocation.

Baseline measurements included dietary assessment (block food frequency questionnaire) and blood pressure. Laboratory evaluation was performed at the General Core Laboratory at WCMC and included a basic metabolic panel, calcium, albumin and thyroid stimulating hormone (TSH). 25-OH and 1,25(OH)2 Vitamin D were measured by radioimmunoassay (Immunodiagnostic Systems, Scottsdale, Arizona). The interassay coefficient of variation (CV) was <8.2% and <13%, respectively. Intact parathyroid hormone (i-PTH) was measured by immunoradiometric assay (Scantibodies Laboratories, Santee, California; CV <6.4%). Markers of bone turnover included osteocalcin (OC: quantitative immunoradiometric assay, DiaSorin, Stillwater, Minnesota; CV <9.5%) , bone specific alkaline phosphatase (BSAP: solid phase monoclonal antibody immunoenzymetric assay, Immunodiagnostics Systems, Scottsdale, Arizona; CV<6.4%), procollagen type 1 amino-terminal propeptide (P1NP: quantitative radioimmunoassay, Orion Diagnostica, Espoo, Finland; CV<9.8%), urinary N-telopeptide (U-NTX: quantitative enzyme-linked immunosorbent assay kit, Wampole Laboratories INC Princeton, New Jersey; CV<5.0%). All specimens were collected as fasting morning samples. The urinary-NTX was a second morning void. The specimens were frozen and batch analyzed. 24 hour urinary collections for calcium, creatinine, sulfate, citrate and sodium were analyzed at Quest Diagnostics. BMD was performed at lumbar spine, total hip and femoral neck using dual-energy X-ray Absorptiometry (DXA) Hologic; Bedford, Massachusetts. The least significant change (LSC) for the DXA was 0.025 at the lumbar spine, 0.025 at the femoral neck and 0.015 at the radius. Two technologists, both certified by the International Society for Clinical Densitometry, performed all DXA testing on the participants.

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 83 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Intervention Model Description: Double Blind Placebo Controlled Trial
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Randomized Placebo Controlled Double Blind Investigation of the Effects of Potassium Citrate on Bone Metabolism in Postmenopausal Osteopenia
Actual Study Start Date : August 2006
Actual Primary Completion Date : April 2011
Actual Study Completion Date : April 2011

Arm Intervention/treatment
Experimental: Potassium Citrate
Potassium Citrate 20 meq twice daily
Drug: potassium citrate
20 meq by mouth in capsule form twice daily
Other Name: uro cit

Placebo Comparator: Placebo
Drug: potassium citrate
20 meq by mouth in capsule form twice daily
Other Name: uro cit

Primary Outcome Measures :
  1. Urinary-N-telopeptide [ Time Frame: Baseline,1,3,6,12 months ]
    One measure of bone turnover was urinary-NTX as a second void morning urine.

  2. P1NP (Amino-terminal Propeptide of Type I Procollagen) [ Time Frame: Baseline,1,3,6,12 months ]
    One measure of bone turnover was P1NP as a morning lab draw.

Secondary Outcome Measures :
  1. Number of Participants With Stable Bone Mineral Density (BMD) Over 12 Months at All Sites. [ Time Frame: 1 year ]
    BMD was performed at lumbar spine, total hip and femoral neck using dual-energy X-ray Absorptiometry (DXA) Hologic; Bedford, Massachusetts.

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Ages Eligible for Study:   45 Years to 75 Years   (Adult, Older Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Postmenopausal women, more than 2 years post menopause
  • Osteopenia, defined as a T score at the lumbar spine or total hip between -1.0 and -2.5
  • No history of prior fragility fracture

Exclusion criteria:

  • Renal insufficiency
  • Use of potassium sparing diuretics
  • Use of potassium supplements
  • Hyperkalemia
  • Secondary causes of osteoporosis or metabolic bone disease
  • Delayed gastric emptying
  • esophageal compression, intestinal obstruction or stricture
  • use of anticholinergic medication
  • active urinary tract infection.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00357331

United States, New York
Weill Cornell Medical College
New York, New York, United States, 10021
Sponsors and Collaborators
Weill Medical College of Cornell University
Principal Investigator: Naina Sinha Gregory, M.D. Weill Medical College of Cornell University

Responsible Party: Weill Medical College of Cornell University Identifier: NCT00357331     History of Changes
Other Study ID Numbers: 0604008486
First Posted: July 27, 2006    Key Record Dates
Results First Posted: June 12, 2017
Last Update Posted: June 12, 2017
Last Verified: May 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

Studies a U.S. FDA-regulated Drug Product: Yes
Studies a U.S. FDA-regulated Device Product: No
Product Manufactured in and Exported from the U.S.: No

Keywords provided by Weill Medical College of Cornell University:
postmenopausal osteopenia
bone loss

Additional relevant MeSH terms:
Bone Diseases
Osteoporosis, Postmenopausal
Metabolic Diseases
Bone Diseases, Metabolic
Musculoskeletal Diseases
Citric Acid
Potassium Citrate
Calcium Chelating Agents
Chelating Agents
Sequestering Agents
Molecular Mechanisms of Pharmacological Action
Natriuretic Agents
Physiological Effects of Drugs
Respiratory System Agents