What Is a Urea Cycle Disorder?

You or your loved one has been diagnosed with a urea cycle disorder (UCD). At first, you may feel overwhelmed. The information about UCDs can be hard to understand, and you may be worried. A urea cycle disorder is a rare condition that is passed down from parent to child. UCDs are caused by one of several genes that does not work the way it should. Because of this, children and adults with UCDs have high levels of ammonia, a poisonous waste product, in their bodies. Click one of the topics below to find out more about UCDs and how the urea cycle works.

UCDs are potentially life-threatening. It's important to speak with your doctor about the right treatment plan for you.

High ammonia levels icon

Know the risks of high ammonia levels

What is hyperammonemia?
Medical cross icon

Learn about ways to treat most urea cycle disorders

Treating most urea cycle disorders
Amy, UCD caregiver with daughter

Discover how UCDs are passed from parent to child

The role of genetics
Family photo of UCD caregivers and patients

Learn how other family members could be at risk

Patients and families

How the urea cycle works

You can get protein from several sources, including the foods you eat, such as meat, fish, eggs, and cheese. As your body breaks down protein, it makes ammonia. The liver helps your body change ammonia into urea, a waste product that comes out in your urine. This process is called the urea cycle.

But in people with UCDs, the liver can't process ammonia properly. This causes too much ammonia to build up in the body. Even if you've never had a hyperammonemic crisis, it doesn't mean that high levels of ammonia in your blood aren't affecting your body. Ammonia levels can go up and down. Over time, if ammonia levels are not kept at a safe level, damage to the body or brain can happen, and may not be reversible.

 

Protein from food breaking down in the stomach and small intestine

There are many places in your body where protein is stored. As protein is broken down, eventually ammonia is produced. The urea cycle's job is to change the extra ammonia that your body doesn't need into something called urea. Urea then leaves your body through the urine.

Protein from food breaking down in the stomach and small intestine

There are many places in your body where protein is stored. As protein is broken down, eventually ammonia is produced. The urea cycle's job is to change the extra ammonia that your body doesn't need into something called urea. Urea then leaves your body through the urine.

Managing a UCD

Learn about urea cycle disorders and how they can be managed.

View more videos
Managing a UCD Video
Read transcript

A urea cycle disorder, also known as a UCD, is a genetic disease that people are born with.

As the body digests protein in food throughout the day, nitrogen is released, and it circulates in the body in the form of ammonia, or NH3.

Normally, most of the ammonia is converted to urea in the liver, and the body gets rid of it via the kidneys in the urine.

However, in people with a UCD, ammonia cannot be turned into urea and can build up to toxic levels and spread throughout the body, including the brain.

An ammonia-removing medicine may be needed to help bind to ammonia, so it can be safely removed from the body.

RAVICTI may help.

RAVICTI is an oral, liquid, ammonia-removing medicine that is taken 3 times daily, and keeps working in your body throughout the day.

When a dose of RAVICTI travels through the body, it is not released right away.

A naturally occurring enzyme found in the digestive tract slowly unlocks RAVICTI so it can be absorbed and start working to bind and remove excessive ammonia.


IMPORTANT SAFETY INFORMATION

Approved Uses for RAVICTI® (glycerol phenylbutyrate) Oral Liquid
RAVICTI is a prescription medicine used in adults and children 2 months of age and older for long-term management of high levels of ammonia in the blood (hyperammonemia) caused by a condition called a urea cycle disorder (UCD). RAVICTI must be used along with a low-protein diet and, in some cases, dietary supplements. RAVICTI should only be used if the UCD cannot be managed with a low-protein diet and dietary supplements alone.

RAVICTI is not used to treat extremely high levels of ammonia in the blood (hyperammonemic crises) in people with UCDs as they may require rapidly acting medication.
It is not known if RAVICTI is safe and effective for the treatment of N-acetylglutamate synthase (NAGS) deficiency.
It is not known if RAVICTI is safe and effective for children younger than 2 months.


Detailed Important Safety Information

Who should not take RAVICTI:
Children younger than 2 months should not take RAVICTI because they may not be able to digest it. Do not take RAVICTI if you are allergic to phenylbutyrate. Call your doctor or go to the nearest hospital emergency room if you have symptoms of an allergic reaction, such as wheezing, shortness of breath, cough, low blood pressure, flushing, nausea, or rash while taking RAVICTI.

RAVICTI may cause serious side effects:
The breakdown of RAVICTI produces the byproduct phenylacetate, which may cause nervous system side effects. Call your doctor or get medical help right away if you have any of these symptoms while taking RAVICTI: sleepiness; lightheadedness; change in taste; problems with hearing; confusion; problems with memory; worsening of numbness, tingling, or burning in your hands or feet; headache, tiredness; nausea; or vomiting.

What are the possible side effects of RAVICTI?
The most common side effects of RAVICTI in adults include diarrhea, gas, headache, nausea, vomiting, tiredness, decreased appetite, and dizziness.

The most common side effects of RAVICTI in children ages 2 to 17 years include stomach pain, nausea, vomiting, diarrhea, decreased appetite, and headache.

The most common side effects of RAVICTI in children ages 2 months to younger than 2 years include decreased level of a type of white blood cell, vomiting, diarrhea, fever, decreased appetite, cough, nasal congestion, runny nose, and rash.

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all of the possible side effects of RAVICTI. Call your doctor for medical advice about side effects.

Before you take RAVICTI:
Tell your doctor if you have liver or kidney problems, pancreas or bowel (intestine) problems, or any other medical conditions. Tell your doctor if you are pregnant or plan to become pregnant. It is not known if RAVICTI will harm your unborn baby. Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if RAVICTI passes into your breast milk. Breastfeeding is not recommended during treatment with RAVICTI. Talk to your doctor about the best way to feed your baby if you take RAVICTI.

Talk to your doctor about participating in a UCD registry. The purpose of this registry is to collect information about people with UCDs to improve care. For more information about the registry program, call 1-855-823-2595 or visit www.ucdregistry.com.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

This information is not comprehensive. To learn more, talk to your healthcare provider or pharmacist. The FDA-approved product labeling, including the Medication Guide, can be found at Ravicti.com.

Symptoms of elevated ammonia levels

Having too much ammonia in your blood is called hyperammonemia (hi-per-am-oh-NEE-me-uh). Here are some symptoms that could mean you or your loved one may have a UCD without even knowing it:

  • Confusion
  • Headache
  • Dizziness
  • Seizures
  • Vomiting
  • Feeling more tired than usual
  • Not being hungry
  • Avoiding protein
  • Growth problems
  • Behavior changes
  • Coma

Even if you're not having a hyperammonemic crisis, daily elevated ammonia levels can be dangerous and cause long-term health problems. That's why it's important to be on the lookout for these subtle signs and symptoms.

Because there are different types of urea cycle disorders, symptoms may happen at different ages and vary from person to person. Many other health conditions have the same symptoms. Only your doctor can make a UCD diagnosis.

Symptoms in babies

Signs of hyperammonemia in babies may be different. A baby with a UCD may be irritable at first, or refuse feedings. This may be followed by vomiting and increasing sleepiness. If left untreated, the baby may have seizures, floppiness, and breathing problems.

Diagnosing urea cycle disorders

Because of the wide range of signs and symptoms, identifying a urea cycle disorder can be difficult. Many other health conditions have similar symptoms as UCDs, so a UCD diagnosis must be made by your doctor.

  • Your doctor can test your blood for high ammonia levels and certain amino acids
  • Further testing such as genetic or enzyme tests can help tell which type of UCD you have

Ask your doctor about a special type of MRI that may help to find areas of the brain that may be affected. It's important to speak with your doctor about your diagnosis. He or she can help you decide on the right treatment plan for you.

Connect with other UCD patients

You don't have to feel alone because you’re living with a urea cycle disorder (UCD). You can share your experiences with other UCD patients and caregivers who know what you're going through because they live with UCDs every day, too. Watch all of the UCD Patient Videos for the stories of other UCD patients and caregivers.

Starting RAVICTI: Amy and Mya's story
Read transcript

VOICEOVER:

Approved Uses for RAVICTI® (glycerol phenylbutyrate) Oral Liquid
RAVICTI is a prescription medicine used in adults and children 2 months of age and older for long-term management of high levels of ammonia in the blood (hyperammonemia) caused by a condition called a urea cycle disorder (UCD). RAVICTI must be used along with a low-protein diet and, in some cases, dietary supplements. RAVICTI should only be used if the UCD cannot be managed with a low-protein diet and dietary supplements alone.

RAVICTI is not used to treat extremely high levels of ammonia in the blood (hyperammonemic crises) in people with UCDs as they may require rapidly acting medication.
It is not known if RAVICTI is safe and effective for the treatment of N-acetylglutamate synthase (NAGS) deficiency.


Amy:

Mya was diagnosed at 6 months old. Our first step was low-protein diet. And she was just on that until about a year. At a year, we added some supplements. At 2 years, we had to add a medication, an ammonia scavenger.

The ammonia scavenger she was on could leave a bad taste in the mouth.

It was, uh, challenging to just flat out get her to take it.

And I thought, "There has to be another treatment."

I was willing to try something new.

So I went to the internet, and I searched and I searched, and I found RAVICTI.

And I thought, I have to get my child on this.

I did talk to my doctor about starting RAVICTI.

I had found most of the information online, so I pretty much sent him a link and said, "Here's this information." And he responded, "Great. I support you."

RAVICTI may not be a fit for everybody. For Mya specifically, it is convenient,

because it's tasteless, it’s odorless. Mya really doesn’t mind taking it.

For us,

starting RAVICTI was pretty easy.

It was easy for her to take,

and the routine was the same, 'cause

she still got the RAVICTI at the same time every day that she got the other one. It was just a

different medication.

Every family's experience is different, but for us,

Mya has been on RAVICTI for almost 6 years,

and we continue to like the convenience

VOICEOVER:
Approved Uses for RAVICTI® (glycerol phenylbutyrate) Oral Liquid
RAVICTI is a prescription medicine used in adults and children 2 months of age and older for long-term management of high levels of ammonia in the blood (hyperammonemia) caused by a condition called a urea cycle disorder (UCD). RAVICTI must be used along with a low-protein diet and, in some cases, dietary supplements. RAVICTI should only be used if the UCD cannot be managed with a low-protein diet and dietary supplements alone.
It is not known if RAVICTI is safe and effective for children younger than 2 months.


Detailed Important Safety Information

Who should not take RAVICTI:
Children younger than 2 months should not take RAVICTI because they may not be able to digest it. Do not take RAVICTI if you are allergic to phenylbutyrate. Call your doctor or go to the nearest hospital emergency room if you have symptoms of an allergic reaction, such as wheezing, shortness of breath, cough, low blood pressure, flushing, nausea, or rash while taking RAVICTI.

RAVICTI may cause serious side effects:
The breakdown of RAVICTI produces the byproduct phenylacetate, which may cause nervous system side effects. Call your doctor or get medical help right away if you have any of these symptoms while taking RAVICTI: sleepiness; lightheadedness; change in taste; problems with hearing; confusion; problems with memory; worsening of numbness, tingling, or burning in your hands or feet; headache, tiredness; nausea; or vomiting.

What are the possible side effects of RAVICTI?
The most common side effects of RAVICTI in adults include diarrhea, gas, headache, nausea, vomiting, tiredness, decreased appetite, and dizziness.

The most common side effects of RAVICTI in children ages 2 to 17 years include stomach pain, nausea, vomiting, diarrhea, decreased appetite, and headache.

The most common side effects of RAVICTI in children ages 2 months to younger than 2 years include decreased level of a type of white blood cell, vomiting, diarrhea, fever, decreased appetite, cough, nasal congestion, runny nose, and rash.

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all of the possible side effects of RAVICTI. Call your doctor for medical advice about side effects.

Before you take RAVICTI:
Tell your doctor if you have liver or kidney problems, pancreas or bowel (intestine) problems, or any other medical conditions. Tell your doctor if you are pregnant or plan to become pregnant. It is not known if RAVICTI will harm your unborn baby. Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if RAVICTI passes into your breast milk. Breastfeeding is not recommended during treatment with RAVICTI. Talk to your doctor about the best way to feed your baby if you take RAVICTI.

Talk to your doctor about participating in a UCD registry. The purpose of this registry is to collect information about people with UCDs to improve care. For more information about the registry program, call 1-855-823-2595 or visit www.ucdregistry.com.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

This information is not comprehensive. To learn more, talk to your healthcare provider or pharmacist. The FDA-approved product labeling, including the Medication Guide, can be found at Ravicti.com.

Family traits

There are 8 different types of urea cycle disorders. Some UCDs are passed from parent to child through genes. Each person has 2 copies of each gene—1 from each parent. Most UCDs happen when a gene that doesn't work gets passed down from both parents to the child.

The most common type of UCD, ornithine transcarbamylase (OTC) deficiency, is different. The gene that doesn't work is passed to a child from the mother. These mothers may not notice any symptoms, although they may be affected by them. It’s important that parents of UCD patients pay attention to little things like headaches, vomiting, confusion, or trouble concentrating. These may be signs of hyperammonemia and you should consider being tested for a UCD.

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The Role of Genetics

Learn how UCDs are passed from parent to child

Who can get a UCD?
Family UCD genetics icon
Amy, UCD caregiver
Amy, UCD caregiver

Real Patients. Real Stories.

"As the mother of a child with a rare disease, you have to find your own voice, and use it."  – Amy | Caregiver

Talk to someone who’s been there

Important Safety Information And Approved Uses For RAVICTI® (glycerol phenylbutyrate) Oral Liquid
Who Should Not Take RAVICTI: Children... Children younger than 2 months should not take RAVICTI because they may not be able to digest it. Do not take RAVICTI if you are allergic to phenylbutyrate. Call your doctor or go to the nearest...

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Important Safety Information And Approved Uses For RAVICTI® (Glycerol Phenylbutyrate) Oral Liquid

Who Should Not Take RAVICTI:

Children younger than 2 months should not take RAVICTI because they may not be able to digest it.

Do not take RAVICTI if you are allergic to phenylbutyrate. Call your doctor or go to the nearest hospital emergency room if you have symptoms of an allergic reaction, such as wheezing, shortness of breath, cough, low blood pressure, flushing, nausea, or rash while taking RAVICTI.

RAVICTI May Cause Serious Side Effects:

The breakdown of RAVICTI produces the byproduct phenylacetate, which may cause nervous system side effects. Call your doctor or get medical help right away if you have any of these symptoms while taking RAVICTI: sleepiness; lightheadedness; change in taste; problems with hearing; confusion; problems with memory; worsening of numbness, tingling, or burning in your hands or feet; headache, tiredness; nausea; or vomiting.

What Are The Possible Side Effects Of RAVICTI?

The most common side effects of RAVICTI in adults include diarrhea, gas, headache, nausea, vomiting, tiredness, decreased appetite, and dizziness.

The most common side effects of RAVICTI in children ages 2 to 17 years include stomach pain, nausea, vomiting, diarrhea, decreased appetite, and headache.

The most common side effects of RAVICTI in children ages 2 months to younger than 2 years include decreased level of a type of white blood cell, vomiting, diarrhea, fever, decreased appetite, cough, nasal congestion, runny nose, and rash.

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all of the possible side effects of RAVICTI. Call your doctor for medical advice about side effects.

Before You Take RAVICTI:

Tell your doctor if you have liver or kidney problems, pancreas or bowel (intestine) problems, or any other medical conditions. Tell your doctor if you are pregnant or plan to become pregnant. It is not known if RAVICTI will harm your unborn baby. Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if RAVICTI passes into your breast milk. Breastfeeding is not recommended during treatment with RAVICTI. Talk to your doctor about the best way to feed your baby if you take RAVICTI.

Approved Uses and Important Safety Information for RAVICTI® (glycerol phenylbutyrate) Oral Liquid

RAVICTI is a prescription medicine for people with UCDs who are at least 2 months of age and cannot manage their UCD with diet and supplements alone. RAVICTI must be used with a low-protein diet. RAVICTI is not used to treat extremely high levels of ammonia in the blood (hyperammonemic crisis) or for NAGS deficiency.

Indication for RAVICTI Oral Liquid

RAVICTI® (GLYCEROL PHENYLBUTYRATE) ORAL LIQUID INDICATIONS AND USAGE

APPROVED USES FOR RAVICTI® (GLYCEROL PHENYLBUTYRATE) ORAL LIQUID

RAVICTI is a prescription medicine used in adults and children 2 months of age and older for long-term management of high levels of ammonia in the blood (hyperammonemia) caused by a condition called a urea cycle disorder (UCD). RAVICTI must be used along with a low-protein diet and, in some cases, dietary supplements. RAVICTI should only be used if the UCD cannot be managed with a low-protein diet and dietary supplements alone.

Limitations Of Use

RAVICTI is not used to treat extremely high levels of ammonia in the blood (hyperammonemic crises) in people with UCDs as they may require rapidly acting medication.

It is not known if RAVICTI is safe and effective for the treatment of N-acetylglutamate synthase (NAGS) deficiency.

It is not known if RAVICTI is safe and effective for children younger than 2 months.

Talk to your doctor about participating in a UCD registry. The purpose of this registry is to collect information about people with UCDs to improve care. For more information about the registry program, call 1-855-823-2595 or visit www.ucdregistry.com.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

This information is not comprehensive. To learn more, talk to your healthcare provider or pharmacist. The FDA-approved product labeling, including the Medication Guide, can be found at RAVICTI.com.

Important Safety Information And Approved Uses For RAVICTI® (Glycerol Phenylbutyrate) Oral Liquid

Who Should Not Take RAVICTI:

Children younger than 2 months should not take RAVICTI because they may not be able to digest it.

Do not take RAVICTI if you are allergic to phenylbutyrate. Call your doctor or go to the nearest hospital emergency room if you have symptoms of an allergic reaction, such as wheezing, shortness of breath, cough, low blood pressure, flushing, nausea, or rash while taking RAVICTI.

RAVICTI May Cause Serious Side Effects:

The breakdown of RAVICTI produces the byproduct phenylacetate, which may cause nervous system side effects. Call your doctor or get medical help right away if you have any of these symptoms while taking RAVICTI: sleepiness; lightheadedness; change in taste; problems with hearing; confusion; problems with memory; worsening of numbness, tingling, or burning in your hands or feet; headache, tiredness; nausea; or vomiting.

What Are The Possible Side Effects Of RAVICTI?

The most common side effects of RAVICTI in adults include diarrhea, gas, headache, nausea, vomiting, tiredness, decreased appetite, and dizziness.

The most common side effects of RAVICTI in children ages 2 to 17 years include stomach pain, nausea, vomiting, diarrhea, decreased appetite, and headache.

The most common side effects of RAVICTI in children ages 2 months to younger than 2 years include decreased level of a type of white blood cell, vomiting, diarrhea, fever, decreased appetite, cough, nasal congestion, runny nose, and rash.

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all of the possible side effects of RAVICTI. Call your doctor for medical advice about side effects.

Before You Take RAVICTI:

Tell your doctor if you have liver or kidney problems, pancreas or bowel (intestine) problems, or any other medical conditions. Tell your doctor if you are pregnant or plan to become pregnant. It is not known if RAVICTI will harm your unborn baby. Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if RAVICTI passes into your breast milk. Breastfeeding is not recommended during treatment with RAVICTI. Talk to your doctor about the best way to feed your baby if you take RAVICTI.

Approved Uses and Important Safety Information for RAVICTI® (glycerol phenylbutyrate) Oral Liquid

RAVICTI is a prescription medicine for people with UCDs who are at least 2 months of age and cannot manage their UCD with diet and supplements alone. RAVICTI must be used with a low-protein diet. RAVICTI is not used to treat extremely high levels of ammonia in the blood (hyperammonemic crisis) or for NAGS deficiency.

Indication for RAVICTI Oral Liquid

RAVICTI® (GLYCEROL PHENYLBUTYRATE) ORAL LIQUID INDICATIONS AND USAGE

APPROVED USES FOR RAVICTI® (GLYCEROL PHENYLBUTYRATE) ORAL LIQUID

RAVICTI is a prescription medicine used in adults and children 2 months of age and older for long-term management of high levels of ammonia in the blood (hyperammonemia) caused by a condition called a urea cycle disorder (UCD). RAVICTI must be used along with a low-protein diet and, in some cases, dietary supplements. RAVICTI should only be used if the UCD cannot be managed with a low-protein diet and dietary supplements alone.

Limitations Of Use

RAVICTI is not used to treat extremely high levels of ammonia in the blood (hyperammonemic crises) in people with UCDs as they may require rapidly acting medication.

It is not known if RAVICTI is safe and effective for the treatment of N-acetylglutamate synthase (NAGS) deficiency.

It is not known if RAVICTI is safe and effective for children younger than 2 months.

Talk to your doctor about participating in a UCD registry. The purpose of this registry is to collect information about people with UCDs to improve care. For more information about the registry program, call 1-855-823-2595 or visit www.ucdregistry.com.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

This information is not comprehensive. To learn more, talk to your healthcare provider or pharmacist. The FDA-approved product labeling, including the Medication Guide, can be found at RAVICTI.com.