Zomacton is an FDA-approved injectable form of synthetic human growth hormone (somatropin). It’s a lab-made version of the growth hormone your pituitary gland naturally produces, used to treat children and adults whose bodies don’t make enough on their own. The medication is given as a subcutaneous injection, either with a traditional syringe or a needle-free device called the ZOMA-Jet.
What Zomacton Treats
In children, Zomacton is approved for several conditions that cause growth failure or short stature:
- Growth hormone deficiency: when the body doesn’t produce enough growth hormone on its own
- Turner syndrome: a chromosomal condition in girls that causes short stature
- Idiopathic short stature: significant short stature (a height standard deviation score of -2.25 or lower) with no identifiable medical cause, where the child’s growth rate makes it unlikely they’ll reach a normal adult height
- SHOX deficiency: a genetic condition affecting a gene involved in bone growth
- Small for gestational age: children born smaller than expected who haven’t caught up in height by age 2 to 4
In adults, Zomacton replaces growth hormone in people with confirmed growth hormone deficiency. This can result from pituitary damage caused by tumors, surgery, radiation, or other conditions. Adults with growth hormone deficiency often experience increased body fat, reduced muscle mass, low energy, and decreased bone density, and replacement therapy helps address these changes.
How It Works in the Body
Zomacton works the same way natural growth hormone does. Its primary effect in children is stimulating the growth plates at the ends of long bones, which is what drives increases in height. It does this partly by raising levels of IGF-1 (insulin-like growth factor 1), a protein that plays a key role in bone and tissue growth. Children with growth hormone deficiency typically have low IGF-1 levels, and treatment with Zomacton brings those levels up to normal ranges.
The effects go well beyond height. Growth hormone influences nearly every tissue in the body. Zomacton increases both the number and size of muscle cells, which matters because children with growth hormone deficiency tend to have fewer skeletal muscle cells than their peers. It also stimulates the growth of internal organs and increases red blood cell production.
On the metabolic side, Zomacton shifts how the body handles fat, protein, and sugar. It mobilizes stored fat and increases the use of fatty acids for energy, reducing overall body fat. It boosts protein production at the cellular level, which supports tissue repair and lean muscle growth. Children with growth hormone deficiency sometimes experience episodes of low blood sugar during fasting, and treatment generally improves this. The medication also helps the body retain minerals like sodium, potassium, and phosphorus, and it stimulates collagen production, which supports connective tissue health.
How Zomacton Is Given
Zomacton is injected just under the skin (subcutaneously). It comes as a powder that needs to be mixed with a liquid diluent before each use. The powder should only be dissolved with the specific solvent provided in the package.
Two delivery options are available. You can use a standard disposable syringe, or you can use the ZOMA-Jet, a needle-free device that pushes the medication through the skin using high-pressure air. The ZOMA-Jet comes in versions matched to the 5 mg and 10 mg vial sizes, so you need the correct device for your dose. For children who are anxious about needles, the needle-free option can make daily injections more manageable.
Dosing is individualized based on body weight, the specific condition being treated, and how the patient responds over time. Your prescriber will adjust the dose based on growth measurements and blood tests.
Storage and Shelf Life
Before mixing, Zomacton needs to be refrigerated between 2°C and 8°C (about 36°F to 46°F) and kept in its outer carton to protect it from light. Once you’ve reconstituted the powder with the provided solvent, the mixed solution lasts up to 14 days in the refrigerator. Store the vial upright. Any medication remaining in the vial after 14 days should be discarded, even if there’s solution left.
Who Should Not Use Zomacton
Zomacton is not appropriate for everyone. It should not be used in children whose growth plates have already closed, since the medication works by stimulating those plates. People with active cancer or active tumors should not take it, as growth hormone can promote cell growth. It’s also not used in critically ill patients, such as those recovering from major surgery or serious trauma, where growth hormone therapy has been associated with increased risk of complications.
Potential Side Effects
The most common side effects are injection site reactions like redness, pain, or swelling. Joint pain and muscle pain occur in some patients, particularly adults. Fluid retention is relatively common and can cause swelling in the hands or feet, or a sensation of stiffness.
More serious but less common effects include increased pressure in the skull (which can cause persistent headaches, nausea, or visual changes), worsening of curvature of the spine in children who are growing rapidly, and changes in blood sugar levels. Because growth hormone affects glucose metabolism, people with diabetes or prediabetes may need closer monitoring. In children, a limp or hip or knee pain could signal a slipped growth plate, which requires prompt medical attention.
Growth hormone therapy also requires periodic monitoring of thyroid function, since treatment can unmask or worsen low thyroid levels. If thyroid hormone drops, it can blunt the growth response, so thyroid levels are checked regularly throughout treatment.
How Zomacton Compares to Other Growth Hormones
Zomacton is one of several brand-name somatropin products on the market. Others include Genotropin, Norditropin, Humatrope, and Nutropin. All contain the same active molecule, a 191-amino-acid protein identical to natural human growth hormone. The differences come down to delivery devices, formulations, storage requirements, and cost. Zomacton’s distinguishing feature is its compatibility with the ZOMA-Jet needle-free system, which isn’t available with all competing brands. Your prescriber and insurance plan will often determine which specific product you use.