Recombinant human parathyroid hormone

Last updated

Recombinant human parathyroid hormone
Clinical data
Trade names Preotact, Natpara, Natpar
AHFS/Drugs.com Monograph
MedlinePlus a617013
License data
Routes of
administration 		Subcutaneous
Drug class Hormonal agent
ATC code
Legal status
Legal status
Identifiers
CAS Number
DrugBank
UNII
KEGG
Chemical and physical data
Formula C408H674N126O126S2
Molar mass 9424.76 g·mol−1

Recombinant human parathyroid hormone, sold under the brand name Preotact among others, is an artificially manufactured form of the parathyroid hormone used to treat hypoparathyroidism (under-active parathyroid glands). [1] [2] [4] [5] Recombinant human parathyroid hormone is used in the treatment of osteoporosis in postmenopausal women at high risk of osteoporotic fractures. [3] A significant reduction in the incidence of vertebral fractures has been demonstrated. [3] It is used in combination with calcium and vitamin D supplements. [1] [4]

Contents

The most common side effects include sensations of tingling, tickling, pricking, or burning of the skin (paraesthesia); low blood calcium; headache; high blood calcium; and nausea. [2]

Recombinant human parathyroid hormone (Preotact) was approved for medical use in the European Union in April 2006. [3] Recombinant human parathyroid hormone (Natpara) was approved for medical use in the United States in January 2015, and in the European Union (as Natpar) in February 2017. [4] [6]

Medical uses

Recombinant human parathyroid hormone (Natpara) is indicated as an adjunct to calcium and vitamin D to control hypocalcemia in people with hypoparathyroidism. [1] [2] Recombinant human parathyroid hormone (Natpar) is indicated as adjunctive treatment of adults with chronic hypoparathyroidism who cannot be adequately controlled with standard therapy alone. [4]

Recombinant human parathyroid hormone (Preotact) is indicated for the treatment of osteoporosis in postmenopausal women at high risk of fractures, [7] but the marketing authorization has been withdrawn at the manufacturer's request. [3]

Contraindications

Parathyroid hormone treatment should not be initiated in patients:

Adverse effects

The most common side effects include too high or too low blood calcium levels, which can lead to headache, diarrhea, vomiting, paraesthesia (unusual sensations like pins and needles), hypoaesthesia (reduced sense of touch), and high calcium levels in the urine. [4]

In the US, the FDA label for parathyroid hormone contains a black box warning for osteosarcoma (a malignant bone tumor). [1]

Interactions

Parathyroid hormone is a natural peptide that is not metabolised in the liver. It is not protein bound and has a low volume of distribution, therefore no specific drug-drug interactions are suspected. From the knowledge of the mechanism of action, combined use of Preotact and cardiac glycosides may predispose patients to digitalis toxicity if hypercalcemia develops.

Undesirable effects

Hypercalcemia and/or hypercalciuria reflect the known pharmacodynamic actions of parathyroid hormone in the gastrointestinal tract, the kidney and the skeleton, and is therefore an expected undesirable effect. Nausea is another commonly reported adverse reaction to the use of parathyroid hormone.

Pharmacodynamic properties

Mechanism of action

Preotact contains recombinant human parathyroid hormone which is identical to the full-length native 84-amino acid polypeptide. Physiological actions of parathyroid hormone include stimulation of bone formation by direct effects on bone forming cells (osteoblasts) indirectly increasing the intestinal absorption of calcium and increasing the tubular reabsorption of calcium and excretion of phosphate by the kidney.

Full-length human parathyroid hormone PTH 1-84.jpg
Full-length human parathyroid hormone

Pharmacodynamic effects

The skeletal effects of parathyroid hormone depend upon the pattern of systemic exposure. Transient elevations in parathyroid hormone levels after subcutaneous injection of Preotact stimulates new bone formation on trabecular and cortical bone surfaces by preferential stimulation of osteoblastic activity over osteoclastic activity.

Effects on serum calcium concentrations

Parathyroid hormone is the principal regulator of serum calcium hemostasis. In response to subcutaneous doses of Preotact (100 micrograms), serum total calcium levels increase gradually and reach peak concentration at approximately 6 to 8 hours after dosing. In general, serum calcium levels return to normal within 24 hours.

Clinical efficacy

In an 18-month double-blind, placebo controlled study, the effects of Preotact on the fracture incidence in 2532 women with postmenopausal osteoporosis was studied. Approximately 19% of patients had a prevalent vertebral fracture at baseline and the mean lumbar T-score of -3.0 in both active and placebo arm. Compared to the placebo group, there was a 61% relative risk reduction of a new vertebral fracture at month 18 for the women in the Preotact group. To prevent one or more new vertebral fractures, 48 women had to be treated for a median of 18 months for the total population. For patients who were already fractured, the number needed to treat was 21.

Effect on bone mineral density

In the same study mentioned above, Preotact increased bone mineral density in the lumbar spine after 18 months treatment by 6.5% compared with a reduction by 0.3% in the placebo group. The difference was statistically significant. The increase of bone mineral density in the hip was also statistically significant compared to placebo, but only around 1.0% at study endpoint. Continued treatment up to 24 months lead to a continued increase in bone mineral density.

Pharmacokinetics

Absorption

Subcutaneous administration of parathyroid hormone into the abdomen produces a rapid increase in plasma parathyroid hormone levels which reach peak at 1 to 2 hours after dosing. The mean half-life is approximately 1.5 hours. The absolute bioavailability of 100 micrograms of Preotact after subcutaneous administration in the abdomen is 55%.

Distribution

The volume of distribution at steady-state following intravenous administration is approximately 5.4 liters. Intersubject variability is about 40%.

Biotransformation

Parathyroid hormone is efficiently removed from the blood by a receptor-mediated process in the liver and is broken down into smaller peptide fragments. The fragments derived from the amino-terminus are further degraded within the cell while the fragments derived from the carboxy-terminus are released back into the blood and cleared by the kidney. These carboxy-terminal fragments are thought to play a role in the regulation of parathyroid hormone activity. Under normal physiological conditions full-length parathyroid hormone H constitutes only 5-30% of the circulating forms of the molecule, while 70-95% is present as carboxy-terminal fragments. Following administration of Preotact, carboxy-terminal fragments make up about 60-90% of the circulating forms of the molecule. Intersubject variability in systemic clearance is about 15%.

Elimination

Parathyroid hormone is metabolised in the liver and to a lesser extent in the kidney. It is not excreted from the body in its intact form. Circulating carboxy-terminal fragments are filtered by the kidney, but are subsequently broken down into even smaller fragments during tubular reuptake. No studies have so far been performed in patients with severe hepatic impairment. The pharmacokinetics of parathyroid hormone in patients with severe chronic kidney disease (creatinine clearance of less than 30 ml/min) has not been investigated either.

Pharmaceutical particulars

Preotact drug cartridge Preotact ampoule.gif
Preotact drug cartridge

Preotact is delivered in a two chamber, glass ampoule. One chamber contains the active substance in the form of a white powder (with excipients: mannitol, citric acid monohydrate, NaCl, NaOH, HCl). And the other contains the solvent; water for injection. The powder is mixed with the solvent when the ampoule is inserted into the injection device.

See also

Related Research Articles

<span class="mw-page-title-main">Osteoporosis</span> Skeletal disorder

Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone sterility, and consequent increase in fracture risk. It is the most common reason for a broken bone among the elderly. Bones that commonly break include the vertebrae in the spine, the bones of the forearm, the wrist, and the hip. Until a broken bone occurs there are typically no symptoms. Bones may weaken to such a degree that a break may occur with minor stress or spontaneously. After the broken bone heals, the person may have chronic pain and a decreased ability to carry out normal activities.

<span class="mw-page-title-main">Parathyroid hormone</span> Mammalian protein found in Homo sapiens

Parathyroid hormone (PTH), also called parathormone or parathyrin, is a peptide hormone secreted by the parathyroid glands that regulates the serum calcium concentration through its effects on bone, kidney, and intestine.

<span class="mw-page-title-main">Calcitonin</span> Amino acid peptide hormone secreted by the thyroid gland

Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH).

Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcemia. Those with a mild increase that has developed slowly typically have no symptoms. In those with greater levels or rapid onset, symptoms may include abdominal pain, bone pain, confusion, depression, weakness, kidney stones or an abnormal heart rhythm including cardiac arrest.

Disorders of calcium metabolism occur when the body has too little or too much calcium. The serum level of calcium is closely regulated within a fairly limited range in the human body. In a healthy physiology, extracellular calcium levels are maintained within a tight range through the actions of parathyroid hormone, vitamin D and the calcium sensing receptor. Disorders in calcium metabolism can lead to hypocalcemia, decreased plasma levels of calcium or hypercalcemia, elevated plasma calcium levels.

Hypoparathyroidism is decreased function of the parathyroid glands with underproduction of parathyroid hormone (PTH). This can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany, and several other symptoms. It is a very rare disease. The condition can be inherited, but it is also encountered after thyroid or parathyroid gland surgery, and it can be caused by immune system-related damage as well as a number of rarer causes. The diagnosis is made with blood tests, and other investigations such as genetic testing depending on the results. The primary treatment of hypoparathyroidism is calcium and vitamin D supplementation. Calcium replacement or vitamin D can ameliorate the symptoms but can increase the risk of kidney stones and chronic kidney disease. Additionally, medications such as recombinant human parathyroid hormone or teriparatide may be given by injection to replace the missing hormone.

<span class="mw-page-title-main">Hyperparathyroidism</span> Increase in parathyroid hormone levels in the blood

Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood. This occurs from a disorder either within the parathyroid glands or as response to external stimuli.

<span class="mw-page-title-main">Teriparatide</span> Pharmaceutical drug for treating osteoporosis

Teriparatide, sold under the brand name Forteo, is a form of parathyroid hormone (PTH) consisting of the first (N-terminus) 34 amino acids, which is the bioactive portion of the hormone. It is an effective anabolic agent used in the treatment of some forms of osteoporosis. Teriparatide is a recombinant human parathyroid hormone analog. It has an identical sequence to the 34 N-terminal amino acids of the 84-amino acid human parathyroid hormone.

<span class="mw-page-title-main">Zoledronic acid</span> Chemical compound

Zoledronic acid, also known as zoledronate and sold under the brand name Zometa by Novartis among others, is a medication used to treat a number of bone diseases. These include osteoporosis, high blood calcium due to cancer, bone breakdown due to cancer, Paget's disease of bone and Duchenne muscular dystrophy (DMD). It is given by injection into a vein.

<span class="mw-page-title-main">Calcitriol</span> Active form of vitamin D

Calcitriol is the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. Calcitriol increases blood calcium (Ca2+) mainly by increasing the uptake of calcium from the intestines.

<span class="mw-page-title-main">Primary hyperparathyroidism</span> Medical condition

Primary hyperparathyroidism is a medical condition where the parathyroid gland produce excess amounts of parathyroid hormone (PTH). The symptoms of the condition relate to the resulting elevated serum calcium (hypercalcemia), which can cause digestive symptoms, kidney stones, psychiatric abnormalities, and bone disease.

<span class="mw-page-title-main">Tertiary hyperparathyroidism</span> Medical condition

Tertiary hyperparathyroidism is a condition involving the overproduction of the hormone, parathyroid hormone, produced by the parathyroid glands. The parathyroid glands are involved in monitoring and regulating blood calcium levels and respond by either producing or ceasing to produce parathyroid hormone. Anatomically, these glands are located in the neck, para-lateral to the thyroid gland, which does not have any influence in the production of parathyroid hormone. Parathyroid hormone is released by the parathyroid glands in response to low blood calcium circulation. Persistent low levels of circulating calcium are thought to be the catalyst in the progressive development of adenoma, in the parathyroid glands resulting in primary hyperparathyroidism. While primary hyperparathyroidism is the most common form of this condition, secondary and tertiary are thought to result due to chronic kidney disease (CKD). Estimates of CKD prevalence in the global community range from 11 to 13% which translate to a large portion of the global population at risk of developing tertiary hyperparathyroidism. Tertiary hyperparathyroidism was first described in the late 1960s and had been misdiagnosed as primary prior to this. Unlike primary hyperparathyroidism, the tertiary form presents as a progressive stage of resolved secondary hyperparathyroidism with biochemical hallmarks that include elevated calcium ion levels in the blood, hypercalcemia, along with autonomous production of parathyroid hormone and adenoma in all four parathyroid glands. Upon diagnosis treatment of tertiary hyperparathyroidism usually leads to a surgical intervention.

<span class="mw-page-title-main">Milk-alkali syndrome</span> Medical condition

Milk-alkali syndrome (MAS), also referred to as calcium-alkali syndrome, is the third most common cause of hypercalcemia. Milk-alkali syndrome is characterized by elevated blood calcium levels, metabolic alkalosis, and acute kidney injury.

<span class="mw-page-title-main">Ibandronic acid</span> Chemical compound

Ibandronic acid is a bisphosphonate medication used in the prevention and treatment of osteoporosis and metastasis-associated skeletal fractures in people with cancer. It may also be used to treat hypercalcemia. It is typically formulated as its sodium salt ibandronate sodium.

<span class="mw-page-title-main">Denosumab</span> Human monoclonal antibody

Denosumab is a human monoclonal antibody for the treatment of osteoporosis, treatment-induced bone loss, metastases to bone, and giant cell tumor of bone.

<span class="mw-page-title-main">Strontium ranelate</span> Chemical compound

Strontium ranelate, a strontium(II) salt of ranelic acid, is a medication for osteoporosis marketed as Protelos or Protos by Servier. Studies indicate it can also slow the course of osteoarthritis of the knee. The drug is unusual in that it both increases deposition of new bone by osteoblasts and reduces the resorption of bone by osteoclasts. It is therefore promoted as a "dual action bone agent" (DABA).

Senile osteoporosis has been recently recognized as a geriatric syndrome with a particular pathophysiology. There are different classification of osteoporosis: primary, in which bone loss is a result of aging and secondary, in which bone loss occurs from various clinical and lifestyle factors. Primary, or involuntary osteoporosis, can further be classified into Type I or Type II. Type I refers to postmenopausal osteoporosis and is caused by the deficiency of estrogen. While senile osteoporosis is categorized as an involuntary, Type II, and primary osteoporosis, which affects both men and women over the age of 70 years. It is accompanied by vitamin D deficiency, body's failure to absorb calcium, and increased parathyroid hormone.

<span class="mw-page-title-main">Parathyroid disease</span> Medical condition

Many conditions are associated with disorders of the function of the parathyroid gland. Some disorders may be purely anatomical resulting in an enlarged gland which will raise concern. Such benign disorders, such as parathyroid cyst, are not discussed here. Parathyroid diseases can be divided into those causing hyperparathyroidism, and those causing hypoparathyroidism.

Abaloparatide, sold under the brand name Tymlos among others, is a parathyroid hormone-related protein (PTHrP) analog medication used to treat osteoporosis. It is an anabolic agent.

<span class="mw-page-title-main">Eldecalcitol</span> Chemical compound

Eldecalcitol is an analog of calcitriol, the active form of vitamin D.

References

  1. 1 2 3 4 5 "Natpara (parathyroid hormone)- parathyroid hormone injection, powder, lyophilized, for solution". DailyMed. Retrieved 8 May 2021.
  2. 1 2 3 4 "FDA approves Natpara to control low blood calcium levels in patients with hypoparathyroidism". U.S. Food and Drug Administration (FDA) (Press release). Archived from the original on 30 January 2015. Retrieved 30 January 2015.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  3. 1 2 3 4 5 "Preotact EPAR". European Medicines Agency. 17 September 2018. Retrieved 3 July 2020.
  4. 1 2 3 4 5 6 "Natpar EPAR". European Medicines Agency. 18 December 2013. Retrieved 28 December 2023. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
  5. ↑ Kim ES, Keating GM (July 2015). "Recombinant Human Parathyroid Hormone (1-84): A Review in Hypoparathyroidism". Drugs. 75 (11): 1293–303. doi:10.1007/s40265-015-0438-2. PMID   26177893. S2CID   2074875.
  6. ↑ "First hormone replacement therapy for parathyroid disorder". European Medicines Agency (EMA) (Press release). 24 February 2017. Retrieved 29 December 2023.
  7. ↑ "Preotact: European Public Assessment Report". European Medicines Agency. 24 April 2006. Archived from the original on 22 June 2009. Retrieved 12 July 2009.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.