What It Is and What It Treats
Headon contains somatropin, a biosynthetic form of human
growth hormone (hGH) produced by recombinant DNA technology, structurally
identical to endogenous pituitary hGH. It is used for:
• Growth hormone deficiency (GHD) in
children and adults
• Turner syndrome in girls
• Short stature in children born small
for gestational age (SGA) who have not shown catch-up growth
• Chronic renal insufficiency (CRI) in
children
• Prader-Willi syndrome (with specific
pre-treatment safety requirements — see below)
Dosing and Administration
Children with GHD:
SUBQ: Initial dose: 0.16 to 0.24 mg/kg weekly, divided
into equal doses 6 to 7 days/week. Dose is weight-based and adjusted by the
treating endocrinologist based on IGF-1 levels and growth response.
Adults with GHD:
Start at 0.15–0.3 mg/day and titrate to IGF-1 levels and
clinical response. Adults generally require lower doses than children.
Reconstitution:
Reconstitute each vial with the supplied bacteriostatic
water for injection. Gently swirl until dissolved — do not shake vigorously
(shaking degrades the protein). The solution should be clear and colourless;
discard if cloudy or particulate.
• Administer by subcutaneous injection,
rotating sites across the abdomen, thighs, and upper arms
• Give in the evening to align with the
body's natural nocturnal GH secretion pattern
• Do not share needles or syringes
between patients
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PATIENT TIP:
After
reconstitution, store in the refrigerator at 2–8°C and use within 14–28 days
(refer to the product insert for the specific Headon batch). Never freeze.
Rotate your injection sites every time to prevent skin thickening at the
injection site (lipohypertrophy). |
Side Effects
|
Frequency |
Side Effects |
|
Common |
Injection site reactions (redness, itching,
bruising), headache, joint and muscle aches, mild fluid retention at
treatment initiation |
|
Less Common |
Hypothyroidism (monitor TFTs), glucose
intolerance (reduced insulin sensitivity), carpal tunnel syndrome |
|
Serious — Seek Urgent Help |
Increased intracranial pressure: persistent
severe headache, nausea, visual changes (papilloedema) — requires urgent
ophthalmological assessment and possible dose interruption. Slipped capital
femoral epiphysis (SCFE) in children: hip or knee pain, limp. Pancreatitis:
severe abdominal pain. Scoliosis progression — monitor spinal alignment in
growing children. |
Contraindications and Cautions
• Active malignancy (current cancer
treatment) — somatropin is absolutely contraindicated
• Closed epiphyses: do not use to
promote linear growth after growth plates have fused
• Acute critical illness post open
heart or abdominal surgery, multiple accidental trauma, or acute respiratory
failure
• Prader-Willi syndrome with severe
obesity or compromised respiratory function — mandatory evaluation for sleep
apnoea before starting; risk of sudden death has been reported in this subset
• Active proliferative or severe
non-proliferative diabetic retinopathy
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CAUTION:
Somatropin
reduces insulin sensitivity and can cause frank hyperglycaemia in susceptible
patients. Monitor blood glucose at initiation and periodically thereafter.
Antidiabetic medication doses may need upward adjustment. |
Key Drug Interactions
Key interactions: glucocorticoids (blunt efficacy), insulin
and oral antidiabetics (adjust doses), oestrogen replacement (reduces
somatropin bioavailability), CYP450 substrates with narrow therapeutic indices.
Frequently Asked Questions
Q: How is Headon different from Genotropin?
Both contain somatropin
(recombinant human growth hormone) and have the same indications and mechanism.
Headon uses individual vials requiring manual reconstitution, while Genotropin
GoQuick is a pre-filled, self-mixing pen device. The pen system is generally
preferred for patient convenience and dose accuracy, particularly for
self-administration at home.
Q: How long does treatment last?
Children with GHD are
typically treated until they reach their final adult height. Adults with GHD may
require lifelong therapy. Your endocrinologist will review treatment needs at
each annual assessment.
Q: What is lipohypertrophy, and how do I prevent it?
Lipohypertrophy is a
thickening and lumpy appearance of fat and skin at injection sites that are
used repeatedly. It can reduce drug absorption and is prevented by
systematically rotating injection sites at every injection — keeping a rotation
map or diagram can help.