Dwarfism often happens because of genetic or inherited conditions. Achondroplasia is the most common form of dwarfism, accounting for about 70% of cases. People with achondroplasia have a relatively long trunk (body not including the head, arms, or legs) and shortened upper parts of their arms and legs. The word achondroplasia means “no cartilage growth.” Cartilage is a tough yet flexible connective tissue that cushions and supports your joints and bones. When cartilage does not grow properly, it prevents normal bone growth and affects height.
Yuviwel is an FDA-approved medicine to help improve growth rates in certain people with achondroplasia. It was first approved in early 2026. Continue reading to learn more about using Yuviwel for achondroplasia.
How Does Yuviwel Work for Achondroplasia?
Achondroplasia happens because of a change in a specific gene in the body, the fibroblast growth factor receptor 3 (FGFR3) gene. This change makes the FGFR3 protein too active. This overactivity interferes with normal bone growth, leading to shorter stature and bone changes.
Yuviwel works like a natural chemical in your body known as C-type natriuretic peptide (CNP). Yuviwel is a prodrug of CNP, meaning it slowly releases CNP to keep levels steady between doses. CNP attaches to a protein called natriuretic peptide receptor-B (NPR-B), activating it. When NPR-B is turned on, it helps block the overactive FGFR3 pathway. As a result, Yuviwel supports the growth and development of cartilage cells (chondrocytes), which promotes healthy bone growth in people with achondroplasia.
How Was It Studied for Achondroplasia?
Before reviewing the study of Yuviwel to improve bone growth in people with achondroplasia, here are a couple of terms that might help you better understand the results.
- Annualized growth velocity (AGV): This describes how quickly your child grows in height over a year. Health care providers measure height at visits and calculate the average speed at which your child grows between visits as a yearly rate. For example, if your child grows 2 centimeters in six months, that equals about 4 centimeters per year. In achondroplasia, AGV helps show whether growth is stable, slowing, or improving with treatment. It does not predict adult height but shows how well treatment is supporting current growth.
- Achondroplasia-specific height Z‑Score: This compares the height of your child with that of other children of the same age and gender who also have achondroplasia. A score of 0 means their height is close to the average height for children who have achondroplasia. A score above 0 means they are taller than average for achondroplasia. A score below 0 means they are shorter than average for achondroplasia. This measure compares your child with peers who share the same condition, rather than with the general population.
Yuviwel was studied in children with achondroplasia in a year-long (52-week) clinical trial to see how well it worked and to make sure it was safe. Everyone in the trial had achondroplasia and had never received treatment. Study participants ranged in age from 2 to 12 years, with an average age of 5.7 years. Just over half of the participants were male (54%), and the rest (46%) were female. Almost all participants were White (88%), with Asian people representing about 10% and mixed race representing about 2% of the participants. Participants ranged in height from 64 to 120 centimeters, with an average of 89 centimeters.
People in the study were randomly assigned to receive weekly injections of either Yuviwel or a placebo (no medicine in it). There were 84 people in the study; 57 of them received Yuviwel, while 27 received placebo. Neither the study participants nor the investigators knew who was receiving Yuviwel or the placebo. The main goal of the study was to see if people receiving Yuviwel grew faster after a one-year period compared to the participants receiving the placebo, using AGV. The investigators also compared each child’s height from the beginning to the end of the study, using their achondroplasia-specific height Z-scores.
What Benefits Were Seen?
People in the study who used Yuviwel got taller faster on average, and their height after treatment seemed to be higher than that of other children of similar gender and age who also have achondroplasia. You can see the specific results from this study in the chart below.
Yuviwel (57 people) | Placebo (27 people) | |
|---|---|---|
| Annualized growth velocity (AGV) in centimeters/year (cm/yr) | 5.9 cm/yr | 4.4 cm/yr |
| Least-squares mean treatment difference* in cm/yr | 1.5 cm/yr | |
| Achondroplasia-specific height Z-score | 0.3 | 0 |
*The “least-squares mean treatment difference” refers to a statistically adjusted average difference between the two groups, accounting for between-group variability. In other words, on average, the people receiving Yuviwel grew about 1.5 centimeters per year taller than those receiving the placebo.
The results of the achondroplasia-specific height Z-score tells us that on average, the children who received Yuviwel were taller than than the average for their age among children with achondroplasia, while the average height of children in the placebo group was essentially the same as the age-specific average for children with achondroplasia.
Yuviwel increased growth rate across ages and genders. However, the treatment difference between Yuviwel and placebo was larger in children aged 5 years or older than in those younger than 5 years. This suggests that older children may see a larger AGV benefit than younger children.
Note that your child’s results may differ from what was seen in this study.
How Do I Use Yuviwel?
Before using Yuviwel for the first time, your health care provider should train you or a caregiver to prepare and use the medicine. Yuviwel comes in a box, and each box has written directions (Instructions for Use) explaining exactly how to prepare and use the medicine, with four kits inside. Read and follow the Instructions for Use. Each kit should be used for one dose and includes the following:
- One vial of Yuviwel
- One prefilled syringe of sterile water
- Two single-use needles to prepare your dose
- One single-use syringe
- One single-use needle to inject your dose
If you are injecting yourself with Yuviwel, inject it under the skin (subcutaneously) in your stomach area or thigh. When injecting into your stomach area, the injection site should be 2 inches away from your belly button. If you are injecting Yuviwel for your child, it can also be injected in your child’s butt or the back of their upper arm.
Before using Yuviwel, you should wash your hands. Below are the general steps to prepare and give Yuviwel. For more detailed instructions, see the Instructions for Use that come with the medicine.
Prepare the medicine:
- If stored in the refrigerator, let the Yuviwel vial and prefilled syringe of water sit at room temperature for about 30 minutes.
- Remove the cap from the Yuviwel vial.
- Wipe the top of the vial with an alcohol swab.
- Break the white cap off of the prefilled syringe of water.
- Attach one of the single-use needles to the syringe and remove the needle cap.
- Push the needle into the top of the Yuviwel vial and squirt the water into the vial.
- Pull the needle out of the vial.
- Gently shake the vial up and down (instead of swirling or rolling) for 15 seconds to fully mix it up, then let it rest for five minutes.
Prepare the injection:
- Attach the unused single-use needle to the injection syringe and remove the cap.
- Pull the plunger back on the syringe to add air to it. The amount of air should equal the volume of Yuviwel you will inject in milliliters (mL).
- Insert the needle into the top of the Yuviwel vial and push the air into the vial.
- Turn the vial upside down with the needle still inside and make sure the needle tip is in the liquid.
- Pull back on the syringe to draw your dose of medicine out of the vial into the syringe.
- Remove the needle from the top of the vial.
- Remove air bubbles.
- Double-check to make sure you drew up the right dose of Yuviwel
- Remove the needle from the syringe.
- Attach the injection needle to the syringe.
Give the injection:
- Pick your injection site, being sure to rotate sites each time you inject the medicine.
- Clean the injection site with an alcohol swab.
- Remove the cap from the needle.
- Insert the needle into the injection site at a 45-degree angle, and slowly push the plunger all the way down.
Throw away any unused medicine in the vial, as it cannot be used for a future dose. Do not recap the needle. Drop all used syringes and needles into your container for used “sharps” equipment. These containers, including the lids, are made of sturdy plastic that are unlikely to leak. If you do not have a sharps container, you can use a heavy-duty plastic household container, such as a laundry detergent container. Do not put this container in the recycling bin. Some communities have specific disposal laws. Check with your local health department for specific disposal instructions in your community.
If you have any questions about how to use Yuviwel, contact your health care provider.
How Can I Prevent and Manage Side Effects?
Some of the most common side effects of Yuviwel include nausea and vomiting or injection site reactions, which include pain, itching, swelling, bruising, skin color changes, small blisters with fluid in them, or redness near the injection site.
If your child has nausea or vomiting with Yuviwel, you can try a few things that may give them some relief:
- Avoid juices and soft drinks; give them water, sports drinks, or broths instead.
- Offer light, bland foods such as crackers, toast, or plain pasta.
- Avoid giving them fried, greasy, or very sweet foods when possible.
- Encourage them to have small, slow meals.
Nausea and vomiting can lead to other problems, such as dehydration. If your child’s nausea or vomiting is severe or you think your child may be getting dehydrated, contact your child’s health care provider.
You should rotate injection sites when using Yuviwel. Doing so may prevent some injection site reactions. Injection site reactions are usually temporary. You can try applying a cold compress to the injection site to provide some relief of redness, pain, or itching. You can also talk to your child’s health care provider to see if over-the-counter antihistamines or pain medicines may be helpful and safe for your child to take.
These are not all of the possible side effects of Yuviwel. Talk with your health care provider if you are having symptoms that bother you. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
Is There Any Assistance Available?
Yes. The drugmaker of Yuviwel offers a support program, Ascendis Signature Access Program (A.S.A.P.) to help you during your child’s treatment with Yuviwel. Once enrolled, you will get a Patient Access Liaison (PAL). Below are the examples of what you can get with this program:
- Direct phone number to reach your PAL
- Educational materials about Yuviwel
- Information about cost savings that may be available
- Help with prior authorization and insurance coverage questions
- Support to avoid gaps in treatment
- Training and support for Yuviwel injections
You can find out more information and enroll in A.S.A.P. by going to this website.