The growth hormone (GH) pen is a specialized, multi-dose delivery system designed for the subcutaneous injection of synthetic human growth hormone (somatropin). This device allows patients to administer their prescribed medication with a high degree of dose accuracy and convenience compared to traditional vials and syringes. GH pens deliver a precise, pre-set dosage of the hormone, used to treat growth failure in children and hormone deficiencies in adults. Because different manufacturers produce various pen models, patients must treat the following steps as a general guide and always refer to the specific instruction booklet provided with their device and healthcare provider.
Preparing the Pen and Setting the Dose
Preparation begins with ensuring proper hygiene and assembling the necessary components for the injection. Start by washing your hands with soap and water before gathering the pen, a new sterile needle, and an alcohol wipe. After removing the cap from the pen, attach a fresh, single-use needle. This is typically done by screwing or snapping it securely onto the pen’s tip until it is firmly in place.
Before the first injection with a new cartridge, or if the pen has not been used recently, it must be “primed” to remove any trapped air. Priming involves dialing a small test dose, often 0.05 mg or two clicks, and holding the pen upright with the needle pointed toward the ceiling. Pressing the injection button should release a tiny stream or a few drops of medication from the needle tip. This confirms that the flow path is clear and ready for use.
Once the pen is primed, dial the exact dose prescribed by your doctor using the dose selector window. If you accidentally dial past the correct number, certain pens allow you to simply dial back to the correct dose. Other models require you to continue dialing forward until the maximum dose is reached, reset the pen, and then dial the correct amount again.
Administering the Injection
Administering the injection involves careful site selection and proper technique to ensure the medication is delivered subcutaneously. Common injection sites include the abdomen, avoiding the two-inch area immediately surrounding the navel, or the front of the thighs. Before the injection, clean the chosen site with an alcohol wipe and allow it to air dry completely to reduce the risk of infection.
After cleaning, gently pinch a fold of skin at the injection site between your thumb and forefinger. This helps separate the subcutaneous fat layer from the underlying muscle. Holding the pen in your dominant hand, insert the needle into the pinched skin at the recommended angle, usually between 45 and 90 degrees. Once the needle is fully inserted, press the injection button or plunger down firmly until the dose counter returns to zero, indicating the full dose has been delivered.
Following the injection, keep the needle inserted in the skin and continue pressing the button for a specific number of seconds, typically five to ten seconds, as recommended by the manufacturer. This waiting period ensures that all the medication has been dispensed from the cartridge and absorbed into the tissue before the needle is withdrawn. After the designated time has passed, release the pinched skin and smoothly pull the pen straight out of the skin.
Safe Disposal and Managing Injection Sites
Immediately after withdrawing the pen, safely remove the used needle from the device to prevent accidental needle sticks. The needle should never be recapped, as this is a common cause of accidental puncture injuries. Detach the entire used needle from the pen and place it directly into an FDA-approved sharps disposal container.
Proper management of injection sites is a major factor in the long-term success of growth hormone therapy, primarily by preventing lipohypertrophy. This complication is the abnormal accumulation of thickened, fatty tissue at frequent injection sites, creating small, rubbery lumps under the skin. Injecting into an affected area can lead to inconsistent or delayed absorption of the growth hormone, compromising treatment effectiveness.
To avoid this, patients should practice site rotation, using a different location for every injection. A practical method involves mentally dividing the injection area, such as the abdomen, and moving systematically from one section to the next. Ensure that each subsequent injection is at least one inch away from the previous site. Regular rotation allows the subcutaneous tissue to heal and maintains consistent drug absorption.
Storage Requirements and Troubleshooting
The stability and effectiveness of synthetic growth hormone depend on strict temperature control, making proper storage a significant consideration. Unopened GH cartridges generally require refrigeration, maintained between 36°F and 46°F (2°C to 8°C). They must be protected from freezing, which can permanently damage the hormone protein. Storage instructions for in-use pens vary widely by brand; some require continuous refrigeration, while others allow storage at room temperature, typically below 77°F (25°C), for up to 21 to 30 days.
Always consult the manufacturer’s guidelines for your specific product, as heat exposure or temperature fluctuations can lead to hormone degradation, reducing its potency. If the medication appears cloudy, discolored, or contains particles, it should be discarded, as these are signs of degradation. The pen should also be protected from direct sunlight and moisture.
If the pen malfunctions during use, such as the dose counter getting stuck or medication leaking, contact a healthcare professional for guidance. Small air bubbles in the cartridge are usually harmless and will not affect the dose. However, any major issue, like a cracked pen casing or an inability to deliver the full dose, should be reported immediately. A GH pen is a personal medical device and must never be shared with anyone else, even if the needle is changed, due to the risk of transmitting blood-borne pathogens.