A Phase 2 interventional study of encaleret in Post-Surgical Hypoparathyroidism, sponsored by National Institute of Dental and Craniofacial Research (NIDCR). Completed at 1 site in United States. Open to participants aged 18 Years to 100 Years. Per ClinicalTrials.gov, last updated 2026-03-11.
Sponsored by National Institute of Dental and Craniofacial Research (NIDCR) · Phase 2, Interventional, and Basic science
Background:
Parathyroid glands in the neck make a hormone that keeps blood calcium levels stable. Sometimes these glands are damaged or removed during neck surgery. This can lead to a condition called postsurgical hypoparathyroidism (PSH). People with PSH have low levels of calcium in their blood. Calcium and vitamin D pills can help them keep their blood calcium levels steady. But this can increase calcium in the urine and result in kidney problems. New treatments for PSH are needed.
Objective:
To test a drug (encaleret) in people with PSH.
Eligibility:
People aged 18 or older who have PSH.
Design:
Participants will be in the study for 6 months. They will have a screening visit and a treatment visit.
Screening will take up to 2 days. Participants will have a physical exam. They will have blood and urine tests and tests of their heart function. They will have an ultrasound of their kidneys; they will lie on a table for 15 to 30 minutes while a wand is moved over their back.
Treatment will require participants to stay in the clinic for 7 days and 6 nights. They will take the study drug (encaleret) by mouth twice a day for 5 days. They will have a small, flexible tube inserted into a vein; this will remain in place during the visit. Blood samples will be taken through the tube 4 to 9 times each day. Participants urine will be collected.
Participants will have follow-up blood tests one (1) week after leaving the clinic. They will have three (3) follow-up phone calls.
Study Description:
This will be a single-site, proof-of-principle, open-label study to explore the PTH-independent effects of encaleret on calcium homeostasis in participants with low or undetectable PTH levels as a result of neck surgery (PSH).
Objectives:
Primary Objective:
-Evaluate the PTH-independent effects of encaleret on renal calcium handling in participants with PSH.
Secondary Objectives:
-Evaluate the ability of encaleret to normalize blood calcium while maintaining a normal urinary calcium in participants with PSH.
Primary Endpoint:
-- Percent change in Fractional Excretion of Calcium (FECa) from baseline (Day -1) to the final day of treatment (Day 6 or the last measurement while on encaleret). FECa calculated using fasting blood levels and spot urine collection.
Secondary Endpoints:
-- Proportion of participants who achieve a concomitant normal or elevated fasting blood calcium (albumin-corrected calcium>8.5 mg/dL) and a normal 24-hour urinary calcium level (\<250 mg/24 hours for women, \<300 mg/24 hours for men) on encaleret at any point between day 1 and day 5.
128 studies on the registry are indexed under Hypoparathyroidism; 30 are open to participants now.
This study's enrollment of 13 is below the median of 50 across 77 interventional studies indexed under Hypoparathyroidism.
Browse Hypoparathyroidism studies →National Institute of Dental and Craniofacial Research (NIDCR) is the lead sponsor of 94 studies on the registry; 9 are open to participants now.
Of its 8 completed or terminated interventional studies of FDA-regulated products, 5 (63%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Participants must meet the following criteria for inclusion during screening:
women are allowed to participate in this study:
a. Women are considered postmenopausal and not of if they have had 12 months of natural (spontaneous) amenorrhea with an appropriate clinical profile (e.g., age appropriate, history of vasomotor symptoms) or have had surgical bilateral oophorectomy (with or without hysterectomy) or tubal ligation at least 6 weeks prior to start of the study. In the case of oophorectomy alone, only when the reproductive status of the woman has been confirmed by follow up hormone level assessment, shall she be considered not of childbearing potential.
EXCLUSION CRITERIA:
Participants who meet any of the following criteria during Screening will not be eligible to participate in the study:
Blood 25-OH Vitamin D level \<25 or >60 ng/mL
Participants with (Hgb) lower than the lower limit of normal.
a. If subject has a low Hgb at the screening visit due to iron, B12, or folate deficiency, they will be prescribed supplementation. Once the Hgb level within the normal range, the subject will be eligible to continue to the treatment phase of the study.
Insufficient hepatic function defined as one of the following:
12-lead resting (ECG) with abnormalities. Participants with screening (using the Fridericia equation) > 450 milliseconds (ms) will not be eligible for the treatment phase of the study.
- If a participant has a prolonged QTcF during screening due to a reversible cause of long QT (for example hypocalcemia or QT-prolonging medications), the subject may be eligible for the treatment phase of the study if the reversible cause can be addressed, and repeat ECG shows QTcF \<=450 milliseconds.
Clinically significant cardiac disease including any of the following:
Women of , defined as all women physiologically capable of becoming pregnant, unless they are using highly effective methods of during dosing and for three (3) months following the discontinuation of study treatment. Highly effective contraception methods include:
Combination of the following (a+c or b+c):
Participants with history of the following:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants with permanent post-surgical hypoparathyroidism (\>1 year after surgery) received encaleret 162 mg orally twice daily for up to five days.
Drug: encaleret
Encaleret 162 mg orally
Percent Change in Fractional Excretion of Calcium (FECa)
The percentage change in Fractional Excretion of Calcium (FECa) from baseline (24 hours before first dose of encaleret) to the last measurement while on encaleret (12 hours after last dose of encaleret). FECa is calculated using fasting blood levels and spot urine collection of calcium and creatinine. Percent change = (last measurement - baseline)/baseline x 100.
Time frame: Last measurement (12 hours after last dose of encaleret), baseline (24 hours before first dose of encaleret)
Proportion of Participants With Concomitant Normal Blood and Urine Calcium
Proportion of participants who achieve a concomitant normal or elevated fasting blood calcium (albumin-corrected calcium\>8.5 mg/dL) and a normal 24-hour urinary calcium level (\<250 mg/24 hours for women, \<300 mg/24 hours for men) on encaleret at any point between day 1 and day 5 while on treatment.
Time frame: Day 1-5 while on treatment
| Milestone | Participants With Permanent Hypoparathyroidism |
|---|---|
| Started | 10 |
| Encaleret for 2 days | 3 |
| Encaleret for 5 days | 7 |
| Completed | 10 |
| Not completed | 0 |
The percentage change in Fractional Excretion of Calcium (FECa) from baseline (24 hours before first dose of encaleret) to the last measurement while on encaleret (12 hours after last dose of encaleret). FECa is calculated using fasting blood levels and spot urine collection of calcium and creatinine. Percent change = (last measurement - baseline)/baseline x 100.
| percentage of change | Participants With Permanent Hypoparathyroidism |
|---|---|
| Percent Change in Fractional Excretion of Calcium (FECa) | -39 ± 29 |
Proportion of participants who achieve a concomitant normal or elevated fasting blood calcium (albumin-corrected calcium\>8.5 mg/dL) and a normal 24-hour urinary calcium level (\<250 mg/24 hours for women, \<300 mg/24 hours for men) on encaleret at any point between day 1 and day 5 while on treatment.
| Proportion of participants | Participants With Permanent Hypoparathyroidism |
|---|---|
| Proportion of Participants With Concomitant Normal Blood and Urine Calcium | 0.9 (0.55 to 1.0) |
Collected over 30 days after last dose of drug intervention. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Participants With Permanent Hypoparathyroidism | 0/10 (0%) | 0/10 (0%) | 10/10 (100%) |
| Event | Participants With Permanent Hypoparathyroidism |
|---|---|
| HypocalcaemiaMetabolism and nutrition disorders | 8/10 |
| NauseaGastrointestinal disorders | 2/10 |
| FatigueGeneral disorders | 2/10 |
| HeadacheNervous system disorders | 2/10 |
| Thrombophlebitis superficialVascular disorders | 2/10 |
| HypothyroidismEndocrine disorders | 1/10 |
| ConjunctivitisEye disorders | 1/10 |
| Abdominal painGastrointestinal disorders | 1/10 |
| Inguinal herniaGastrointestinal disorders | 1/10 |
| PneumoniaInfections and infestations | 1/10 |
| Age, Categorical(Participants) | Participants With Permanent Hypoparathyroidism |
|---|---|
| <=18 years | 0 |
| Between 18 and 65 years | 9 |
| >=65 years | 1 |
| Sex: Female, Male(Participants) | Participants With Permanent Hypoparathyroidism |
|---|---|
| Female | 9 |
| Male | 1 |
| Ethnicity (NIH/OMB)(Participants) | Participants With Permanent Hypoparathyroidism |
|---|---|
| Hispanic or Latino | 1 |
| Not Hispanic or Latino | 9 |
| Unknown or Not Reported | 0 |
| Race (NIH/OMB)(Participants) | Participants With Permanent Hypoparathyroidism |
|---|---|
| American Indian or Alaska Native | 0 |
| Asian | 0 |
| Native Hawaiian or Other Pacific Islander | 0 |
| Black or African American | 0 |
| White | 10 |
| More than one race | 0 |
| Unknown or Not Reported | 0 |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes — All anonymized individual participant data (IPD) that underlie results in a publication
Time frame: starting 6 months after publication in peer-reviewed journals
Access criteria: Anonymized data will be shared on reasonable request to the principal investigator.
Ran from Sep 2023 to primary completion in May 2025, 20 months.
Results were first posted in Mar 2026, 9 months after primary completion.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Feb 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Encaleret
National Institute of Dental and Craniofacial Research (NIDCR) →