Jynarque

Indications for Use

Jynarque is used to treat a specific genetic condition called autosomal dominant polycystic kidney disease (ADPKD). In people with this condition, numerous fluid-filled cysts develop and grow in the kidneys. Over time, these cysts can damage the kidneys and lead to a decrease in kidney function or kidney failure.

Target Patient Population

Healthcare providers prescribe Jynarque for adults who meet the following criteria:

• They have been diagnosed with ADPKD.
• They are considered at high risk for their kidney function declining quickly.

The primary goal of treatment is to slow the rate at which kidney function worsens, helping to maintain kidney health for as long as possible. It is not a cure for ADPKD, but it helps manage the progression of the disease in specific patients.

Mechanism of Action

Jynarque belongs to a class of medications known as vasopressin V2-receptor antagonists. It is specifically used to slow the progression of autosomal dominant polycystic kidney disease (ADPKD), a genetic condition where fluid-filled cysts grow and multiply, eventually causing the kidneys to enlarge and lose function.

The medication works by targeting a hormone called vasopressin, also known as antidiuretic hormone. In people with ADPKD, vasopressin levels contribute to the development and expansion of kidney cysts. Jynarque works through the following processes:

• Blocking receptors: The drug prevents vasopressin from binding to V2 receptors located in the collecting ducts of the kidneys.
• Slowing cyst expansion: By blocking these receptors, Jynarque reduces the levels of chemical signals that cause kidney cells to multiply and secrete fluid into the cysts.
• Increasing water excretion: Because vasopressin normally helps the body retain water, blocking its effect causes the kidneys to release more water into the urine. This process is known as aquaresis.

By interfering with these pathways, Jynarque helps to slow the rate at which the kidneys increase in size and helps to maintain kidney function for a longer period of time.

Common Side Effects

The most frequent side effects of Jynarque are often related to how the drug affects fluid balance in the body. These may include:

• Thirst and dry mouth
• Frequent urination, including at night
• Fatigue
• Diarrhea
• Dizziness
• Headache
• Nausea

Serious Side Effects

Contact a healthcare provider immediately if you experience any of the following serious symptoms:

• Liver injury: Signs include yellowing of the skin or eyes (jaundice), dark urine, pain in the upper right abdomen, nausea, vomiting, or loss of appetite.
• Dehydration: Symptoms include extreme thirst, dry skin, confusion, or feeling faint.
• Allergic reactions: Signs include rash, hives, itching, or swelling of the face, throat, or tongue.

Because Jynarque can cause significant changes in water and sodium levels, your doctor will monitor your blood work and liver function regularly during treatment. It is important to drink enough water to respond to thirst and to follow your provider's instructions regarding fluid intake.

Serious Liver Injury

Jynarque can cause serious and potentially fatal liver injury. Because of this risk, it is only available through a restricted program called the Jynarque REMS (Risk Evaluation and Mitigation Strategy). Healthcare providers must monitor liver function through blood tests before starting the medication, monthly for the first 18 months of treatment, and every 3 months thereafter.

Contraindications

Jynarque should not be used by individuals who:

• Have a history of significant liver impairment or injury.
• Are unable to sense or respond to thirst.
• Are dehydrated or have low blood volume.
• Have an allergy to tolvaptan or any ingredients in the medication.
• Are taking strong CYP3A inhibitors.
• Have uncorrected high or low blood sodium levels.

Hydration and Electrolyte Balance

This medication increases water loss through urine, which can lead to dehydration and high blood sodium levels (hypernatremia). It is important to have access to water and drink whenever thirsty, including during the night. If a person is unable to drink enough water or loses excessive fluids through vomiting or diarrhea, the medication may need to be paused.

Drug Interactions

Certain medications and substances, such as grapefruit juice and strong CYP3A inhibitors, can significantly increase the levels of Jynarque in the body, raising the risk of side effects. Conversely, some medications may decrease its effectiveness.

Pregnancy

Jynarque may cause harm to an unborn baby. Animal studies have shown that the medication can cause fetal harm when administered during pregnancy. If you are pregnant or planning to become pregnant, talk to your healthcare provider about the potential risks and benefits of this treatment.

It is important to use effective birth control while taking Jynarque. If you become pregnant during treatment, notify your doctor immediately.

Breastfeeding

It is unknown whether Jynarque passes into human breast milk. Because there is a potential for serious side effects in a nursing infant, breastfeeding is not recommended during treatment with this medication. Discuss the best way to feed your baby with your healthcare provider if you are taking Jynarque.

Available Forms

Jynarque is supplied as a tablet for oral administration. These tablets are typically provided in specialized blister packs designed for a twice-daily dosing regimen, containing two separate tablets to be taken at different times of the day.

FDA Approval and Indications

Jynarque was approved by the U.S. Food and Drug Administration (FDA) specifically to slow the decline of kidney function in adults at risk of rapidly progressing autosomal dominant polycystic kidney disease (ADPKD). It is the first FDA-approved treatment for this condition.

Boxed Warning for Liver Injury

The FDA has issued a boxed warning for Jynarque because it can cause serious and potentially fatal liver injury. Due to this risk, healthcare providers must perform blood tests to check liver function before starting the medication, every month for the first 18 months of treatment, and every three months thereafter.

REMS Program

Because of the risk of liver damage, Jynarque is only available through a restricted distribution program called the Jynarque REMS (Risk Evaluation and Mitigation Strategy) Program. This regulatory requirement ensures that:

• Prescribers are certified and educated on the risks of liver injury.
• Pharmacies are certified to dispense the medication only to patients who are enrolled in the program.
• Patients are enrolled in the program and comply with the mandatory liver monitoring schedule.

Regulatory Requirements for Patients

Patients must be informed of the risks before starting treatment. If a patient misses a required liver test, the pharmacy may be unable to refill the prescription until the testing is completed. Patients are also instructed to stop the medication immediately and contact their doctor if they experience symptoms of liver problems, such as yellowing of the skin or eyes, dark urine, or pain in the upper right stomach area.

Specific pricing information for Jynarque is not available in the provided medical sources. The cost of the medication may be influenced by its restricted distribution and the requirements for patient monitoring.

Restricted Access

Jynarque is only available through a restricted program called the Jynarque REMS (Risk Evaluation and Mitigation Strategy). This program is required by the FDA because tolvaptan can cause serious and potentially fatal liver injury. Under this program:

• Jynarque can only be dispensed by certified pharmacies.
• Patients must be enrolled in the program and comply with required liver monitoring tests.
• Healthcare providers must also be certified to prescribe the medication.

Because Jynarque is not available at all retail pharmacies, patients must obtain the medication through specific channels. For information regarding the cost and the process for receiving the drug, patients should speak with their healthcare provider or a pharmacy certified under the Jynarque REMS program.