Achondroplasia is a type of dwarfism that affects the growth in children, leading to a short stature or small size. Achondroplasia is a rare genetic condition that affects one in every 15,000 to 40,000 newborns. It can lead to additional complications or health concerns as you get older, including obesity, ear infections/hearing loss, neurological problems that affect the brain and spinal cord, and crooked teeth. Voxzogo (vox-ZOE-goe) is an injection medicine that was approved in 2021 for the treatment of achondroplasia. It is the first FDA-approved treatment for achondroplasia in children with open growth plates.
How Does It Work for Achondroplasia?
Growth plates are areas at the ends of certain bones that allow the bones to grow. As a child grows, those growth plates remain open. Growth plates are made of cartilage, which is a type of strong and flexible tissue. As a child grows, the cartilage turns into bone. Once the growth plates are closed, a child stops growing.
Symptoms of achondroplasia are listed below.
- Shortened arms, legs, hands, feet, fingers, or thighs
- Larger than normal head size
- Large forehead with flattened nose
- Curved spine
- Bow legs, where the legs are bent outward
Achondroplasia can be passed down from parent to child, but in most cases, it happens spontaneously. In children who have achondroplasia, there is a mutation in their DNA that disrupts signaling between certain proteins in the body. There are two different signaling pathways in your body, one that increases bone growth, and the other that slows down bone growth. The mutation found in achondroplasia increases the signaling between the proteins that slow bone growth. Voxzogo works by increasing the protein signaling that causes an increase in the rate of bone growth and bone development. The goal is to use Voxzogo while you have open growth plates and stop using the medicine once the growth plates have closed. Your health care provider will determine if you are no longer able to grow and tell you when you should stop taking Voxzogo.
How Do I Use It?
Voxzogo comes as an injection that you will give to your child once a day, around the same time each day. It is injected under the skin in either the thighs, stomach (2 inches away from the belly button), butt, or back of the upper arms. Do not inject Voxzogo into the same injection site two times in a row. Rotate where you inject Voxzogo to prevent skin irritation. Do not inject Voxzogo in skin that is swollen, sore, bruised, red, hard, or scarred. It is important for your child to eat a meal and drink a glass (about 8 to 10 ounces of fluid) of either water, milk, or juice one hour before receiving the injection. This can help prevent your child from developing low blood pressure, which can lead to tiredness and dizziness that the medicine may cause.
The dose you will give to your child will depend on their weight. Tell your health care provider if your child’s weight has changed. Your health care provider will tell you how much Voxzogo to give your child. Your health care provider can train you on how to properly give Voxzogo to your child. It is important that you also read the step-by-step instructions on how to correctly prepare and give Voxzogo to your child through the Instructions For Use paper that comes with the medicine. If you have any questions about how to give the medicine or any additional supplies you may need, you can also talk to your health care provider. Do not try to inject Voxzogo until you have been shown how to use the medicine. The drugmaker also has a program that can provide support with learning more about Voxzogo and details around injection training. Talk to your health care provider to learn more.
How Was It Studied for Achondroplasia?
A clinical study was conducted to look at the safety and effectiveness of Voxzogo in children with achondroplasia. The study measured growth rate in terms of change in height over 52 weeks. About 53% of children were males and 47% were females. The average age of people in the study was 9 years old and included White people (71%), Asian people (19%), Black people (4%), and Hispanic or Latino people (6%), with 6% of children classified as being more than one race. A majority of children went into another type of study, called an extension study, that looked at growth beyond one year.
What Benefits Were Seen?
Patients in the Voxzogo group showed on average a growth of 1.4 centimeters at 52 weeks (1 year). In the extension study, children taking Voxzogo maintained their height improvement. This showed that Voxzogo increased the growth rate in children with achondroplasia.
Your results may differ from what was seen in clinical studies.
How Long Does It Take to Work?
Based on clinical studies, children started to have an increase in their growth several months after using Voxzogo. Growth rate, however, can vary. Keep all appointments with your health care provider while using Voxzogo. Your health care provider can monitor your progress as well as how you are tolerating the medicine.
What Are the Side Effects and How Can I Manage Them?
Because Voxzogo comes as an injection, a common side effect from the medicine is an injection site reaction. This can include redness, swelling, rash, bruising, hives, and pain where the needle goes in the skin. Applying a cool compress to the area may help. Your health care provider or pharmacist may recommend an over-the-counter (OTC) pain reliever, such as acetaminophen, or an OTC antihistamine for itching. Talk to your health care provider if you experience an injection-site reaction and before taking any medicines to help with your symptoms. Rotating your injection sites can also help minimize injection site reactions.
Voxzogo can also cause low blood pressure. Make sure you stand up slowly and use support if needed. If you feel dizzy or faint, sit or lie back down. To help minimize the risk of low blood pressure, make sure you drink 8 to 10 fluid ounces of water, milk, or juice and eat a meal one hour before using Voxzogo. Call your health care provider if you have low blood pressure or dizziness that does not improve or gets worse.
Joint pain, stomach flu (gastroenteritis), and vomiting can occur while using Voxzogo. Talk to your health care provider if you are experiencing these symptoms. Your health care provider may ask you to keep certain OTC medicines on hand or suggest additional treatment options. If you are experiencing stomach problems or vomiting, drink plenty of water and try to eat smaller meals throughout the day. Eating bland foods such as crackers, broth, bananas, and toast can help. Call your health care provider if these symptoms do not go away or get worse.
Voxzogo can also cause an increase in a laboratory test called alkaline phosphatase. Alkaline phosphatase can measure the function of your liver or bone. Keep all appointments with your health care provider to get your blood checked while using Voxzogo.
Is Voxzogo Right for Me?
Talk to your health care provider if you have any kidney problems. It is unknown how Voxzogo can affect your kidneys, but if you have certain types of kidney problems, your health care provider may not use Voxzogo.
Is There Any Cost Assistance Available?
There is a cost savings program available from the drugmaker’s website that may allow you to pay as little as $0 for your medicine. Whether you are eligible depends on the type of health insurance you have. You can find out more by visiting www.biomarin-rareconnections.com/voxzogo/voxzogo-enroll or by calling 833-869-9646.
Getting a Specialty Medicine: What to Expect
Your health care provider will prescribe Voxzogo. It is a specialty medicine, which is a high-cost medication that is taken for rare, complex, or chronic (long-term) diseases. It will require a different process than picking up a prescription at your local pharmacy. You will use a specialty pharmacy for getting this medicine. The specialty pharmacy will reach out to you to discuss the details about how to ship Voxzogo to your house.
Your insurance may require approval for using Voxzogo, also called prior authorization. The insurance company reviews the prescription from your health care provider to make sure it is covered and determines the process that needs to be followed.
You may also be able to work with a representative from the drugmaker that can help you through the process of insurance coverage and with details around the specialty pharmacy shipping the medicine.