Palopegteriparatide for Hypoparathyroidism: Dose, Side Effects, Administration and Pharmacology

Overview:

Adults with persistent hypoparathyroidism can be treated with hormone replacement therapy using Palopegteriparatide. The disease is characterized by insufficient production of parathyroid hormone (PTH) by the parathyroid glands in the neck, which regulate blood calcium levels. Due to low calcium levels, patients may have issues with their bones, muscles, heart, kidneys, and other organs.

Palopegteriparatide was named an "orphan medicine" (used in rare conditions) on October 19, 2020. Hypoparathyroidism is an uncommon condition. In August 2024, the United States Food and Drug Administration (FDA) licensed Palopegteriparatide injection for subcutaneous use in individuals with hypoparathyroidism. Adults with acute post-surgical hypoparathyroidism were not evaluated for Palopegteriparatide.

Drug Group:

Palopegteriparatide belongs to the parathyroid hormone analogs drug group, which is used for the treatment of hypoparathyroidism.

Available Doses and Dosage Forms:

• Form: Injectable prefilled pen containing subcutaneous solution.

• Doses:

• 168 micrograms per 0.56 milliliters (mcg/mL), doses 6, 9, or 12 mcg;

• 294 mcg per 0.98 mL, doses 15, 18, or 21 mcg;

• 420 mcg per 1.4 mL, doses 24, 27, or 30 mcg.

For Patients:

How Does Palopegteriparatide Work?

One artificial counterpart of parathyroid hormone is called Palopegteriparatide. It functions as follows:

• By stimulating calcium release into the circulation, it mimics PTH (parathyroid hormone) and helps elevate blood calcium levels.

• It enhances calcium absorption and raises blood calcium levels by encouraging calcium absorption from the intestines and reducing calcium excretion by the kidneys.

• The composition permits constant PTH exposure, preserving steady calcium levels for a full day.

What Is the Dosage of Palopegteriparatide?

The maximum recommended dosage for Palopegteriparatide is 30 mcg subcutaneously once daily; use just one injection to get the once-daily recommended dosage. Using two injections increases the variability in the total dosage, which might lead to unintentional variations in blood calcium levels, such as hypo and hypercalcemia.

How Effective Is Palopegteriparatide?

In major research involving 84 hypoparathyroidism patients, palopegteriparatide was found to be more efficient than a placebo at maintaining blood calcium levels within the normal range. After using Palopegteriparatide for 26 weeks, 48 out of 61 patients, or around 79 percent of the patients, who were on a stable dosage, had normal blood calcium levels and were no longer in need of traditional therapies, which included high-dose calcium supplements and active vitamin D. In contrast, five percent (one out of 21 patients) received a placebo.

What Are the Things to Inform the Doctor Before Taking the Drug?

Inform the physician before using Palopegteriparatide about the following:

• Any documented or known allergy to the ingredients in Palopegteriparatide.

• Any past medical history of certain illnesses, such as bone cancer (osteosarcoma).

• Elevated calcium levels (hypercalcemia).

• Diseases of the urinary tract or kidney.

• Provide a list of all the drugs, herbal items, and supplements presently used since they may cause interactions with Palopegteriparatide.

How Is Palopegteriparatide Administered?

• Before administering, visually check for particles and discoloration; the solution should seem clear and colorless.

• If solid particles form or the solution seems hazy or tinted, do not use them.

• Upon initial usage, check the flow of the pen.

• Screw the needle onto the pen until it is securely in place after clicking it on.

• Administer subcutaneous in the front or abdomen; switch up the injection location every day.

• Because orthostatic hypotension may occur, have the patient lie down or sit while receiving treatment.

• To keep blood calcium levels within the normal range, the beginning dosage is 18 mcg once a day and is titrated in three mcg increments or decrements. This may be done without the requirement for therapeutic calcium dosages (elemental calcium greater than 600 mg per day) or active vitamin D (for example, calcitriol). Supplementing with enough calcium to satisfy daily dietary needs can go on.

What Are the Side Effects of Palopegteriparatide?

The following are the side effects experienced by the patient:

• Reactions at the injection location (39 percent).

• Signs and symptoms of vasodilation (dilation on blood vessels) (28 percent).

• Headache (21 percent).

• Diarrhea (loose motion) (10 percent).

• Back discomfort (eight percent).

• Hypercalcemia (increased calcium in blood) (eight percent).

• Pain in the oropharynx (seven percent).

Dietary Considerations:

• Include enough calcium and vitamin D in the diet. These minerals are important for healthy bones and can increase the efficacy of Palopegteriparatide.

• Drink enough water to support kidney function because the medication may lower calcium levels.

• If the doctor advises it, avoid foods high in phosphate, such as processed meals and dairy products, as hypoparathyroidism can cause higher phosphate levels.

Missed Dose:

• If one misses a dose by less than 12 hours, take it as soon as possible.

• If a dose is missed by more than 12 hours, ignore the missing dose and take the next one on time.

• If the dose is delayed or stopped for over three days, examine for hypocalcemia symptoms and indicators and measure blood calcium. Continue taking calcium supplements and active vitamin D at higher doses or restart therapy if necessary. After a break, take Palopegteriparatide at the recommended dosage as soon as feasible. Within seven to ten days, check blood calcium levels and modify Palopegteriparatide, active vitamin D, and calcium supplement dosages.

Overdose:

Overdose of Palopegteriparatide may cause severe hypercalcemia and shows the following symptoms:

• Vomiting and nausea.

• Constipation.

• Stomach ache.

• Perplexity or changed mental state.

• Weakened muscles.

• Increased urination and thirst.

Seek immediate medical attention in such a case. Head to the closest hospital or call emergency services if one has been overdosed.

Storage

• After each use, remove the needle and replace the pen cap to shield it from light.

• Throwing away the prefilled pen 14 days after the first use is advisable.

• Do not freeze the pen.

• Store the pen away from heat.

• To keep it safe from light, keep it in its original container.

• Refrigerate at two to eight degrees Celsius (36 to 46 degrees Fahrenheit) until first use. Store at room temperature for 14 days after first use.

For Doctors:

Indication:

A parathyroid hormone analog (PTH(1-34)) called Palopegteriparatide is prescribed to treat adult hypoparathyroidism.

Dose:

• Initial Dose: 18 micrograms (mcg) subcutaneously per day. Modify dosage in increments or decreases of three micrograms. Take no more than one dose, which can be increased every seven days. Limit dosage reductions to every three days.

• Maintenance Dose: The suggested dosage range is six to 30 mcg daily.

Customize the maintenance dose to get the blood calcium level within the normal range without requiring therapeutic calcium dosages or calcitriol. If calcium levels do not improve after taking the maximum amount of calcium (30 mcg/ per day), consider starting or resuming calcitriol or calcium medication or looking for alternative forms of care.

Dosing Considerations:

• Laboratory examinations are recommended before starting. Two weeks before the initial dosage, verify that blood calcium adjusted for albumin is less than 7.8 mg/dL and serum 25(OH) vitamin D is within the normal range.

• Limitations: Acute post-surgical hypoparathyroidism has not been explored. The titration scheme was only assessed in people who received calcium and active vitamin D therapy to reach an albumin-corrected blood calcium level of ≥7.8 mg/dL (milligrams per deciliter or greater).

What Are the Pharmacological Aspects of Palopegteriparatide?

• Pharmacodynamics: A recombinant version of parathyroid hormone (PTH) called Palopegteriparatide promotes bone growth and increases calcium absorption in the kidneys and intestines. It increases bone density and promotes bone remodeling mainly by acting on osteoblasts. Giving Palopegteriparatide to healthy participants resulted in dose-related increases in blood PTH (1-34) and calcium concentrations. Hypoparathyroid individuals lack established exposure-response relationships.

• Mechanism: Parathyroid hormone prodrug releases PTH(1-34) to keep the systemic exposure constant. Endogenous PTH preserves extracellular calcium and phosphate balance by raising blood calcium and lowering serum phosphate. These benefits are achieved by improving renal calcium reabsorption and phosphate excretion, increasing intestinal absorption of calcium and phosphate through increased bone turnover, and enabling active vitamin D production. Similar to natural PTH, parathyroid hormone 1 receptor (PTH1R), which is extensively expressed on osteoblasts, osteocytes, renal tubular cells, and in various other organs, is how PTH(1-34) produced from Palopegteriparatide exerts these effects.

• Pharmacokinetics

• Absorption: Four (four to eight) hours is the median (range) amount of time needed to attain PTH maximum concentrations (Tmax).

• Distribution: Palopegteriparatide's estimated apparent volume of distribution (CV%) is 4.8 (50) L (liter). The distribution pattern of PTH produced by Palopegteriparatide is anticipated to be comparable to that of endogenous PTH.

• Excretion: PTH produced from Palopegteriparatide has an apparent half-life of around sixty hours. At a steady state, the estimated clearance (CV%) of Palopegteriparatide is 0.58 (52) L/day.

• Metabolism: PTH(1-34) and PTH(1-33), the active metabolite, are examples of released PTH. PTH(1-33) and PTH(1-34) activate PTH1R with similar affinities.

Toxicity:

• Common Side Effects: Injection site reactions, headaches, nausea, and exhaustion are possible.

• Serious Risks: Patients who have a history of skeletal abnormalities or who are taking large dosages of the medication may be at risk for osteosarcoma.

• Monitoring: Regular monitoring of calcium levels is advised to control possible hypercalcemia.

Clinical Studies:

82 people with hypoparathyroidism were included in the 26-week clinical trial (Study 1, NCT04701203), which was planned as a randomized, double-blind, placebo-controlled experiment to assess Palopegteriparatide as a therapy for the disease. Participants went through a screening process to ensure their calcium and vitamin D levels were optimal before being randomly assigned. As of week 26, the effectiveness criteria were met by 68.9 percent (42 out of 61 individuals) in the Palopegteriparatide group, whereas only 4.8 percent (1 out of 21 participants) in the placebo group completed the requirements. This is a substantial treatment difference of 64.2 percent. Additionally, at weeks 52 and 78, the long-term effectiveness was evaluated when 39 (64 percent) and 40 (66 percent) of the subjects maintained normal calcium levels and treatment independence.

The results of this study demonstrate the safety and effectiveness of Palopegteriparatide as a therapy option for adult hypoparathyroidism in the population under study.

The main efficacy goal was attaining normal blood calcium levels and freedom from traditional treatment. At week 26, the success rates showed that just 4.8 percent (1 out of 21 participants) and 68.9 percent (42 out of 61 participants) in the Palopegteriparatide group had fulfilled the effectiveness requirements.

What Are the Contraindications of Palopegteriparatide?

Severe hypersensitivity or allergy to any of the ingredients in Palopegteriparatide, including Palopegteriparatide.

Warnings and Precautions:

• Unintentional Variations in Serum Calcium Levels Associated with Daily Injection Count: Take one injection of Palopegteriparatide every day. The variability of the total administered dose rises when the prescribed once-daily dosage is met by using two Palopegteriparatide injections.

• Serious Hypo- and Hypercalcemia: Palopegteriparatide has been associated with these conditions. Measure serum calcium regularly and watch for symptoms of hypo- and hypercalcemia.

• Possible Risk of Osteosarcoma: Patients with a higher risk of osteosarcoma should not use Palopegteriparatide.

• Orthostatic Hypotension: A case of Palopegteriparatide has been documented. Look for orthostatic hypotension symptoms and indicators.

• Digoxin Toxicity: If hypercalcemia occurs, concurrent use of Digoxin and other medications may increase the risk of Digoxin toxicity. Measure blood calcium and Digoxin levels often when used concurrently, and watch for any indications of Digoxin toxicity.

What Are the Drug Interactions of Palopegteriparatide?

• Medications Impacted by Serum Calcium Digoxin: Because Palopegteriparatide raises blood calcium, using Digoxin concurrently with other medications with a limited therapeutic index might put patients at risk for digitalis toxicity if hypercalcemia occurs. Hypocalcemia may decrease the effectiveness of Digoxin. Measure blood calcium and Digoxin levels when using Palopegteriparatide concurrently with Digoxin, and keep an eye out for any indications of Digoxin toxicity. Digoxin and Palopegteriparatide dosage adjustments could be required.

• Medications Known to Impact Serum Calcium: Medication affecting blood calcium levels may change how well Palopegteriparatide works as a treatment. When Palopegteriparatide is taken concurrently with these medications, especially after they are started, stopped, or changed dosage, serum calcium is measured more often.

Specific Considerations:

• Pregnancy: There is not enough information available from reports of pregnancies in clinical trials related to medication development to determine if there is a drug-associated risk of serious birth abnormalities, miscarriage, or other unfavorable outcomes for either the mother or the fetus. If Palopegteriparatide is given to a patient who becomes pregnant while on Palopegteriparatide, medical professionals should report Palopegteriparatide exposure.

• Breastfeeding: Mothers who use Palopegteriparatide should watch for signs of hypo- or hypercalcemia in their infants. If the baby is breastfed, note the baby's blood calcium levels.