Terrosa (Teriparatide)
Parathyroid hormone analogue for osteoporosis treatment
Terrosa contains teriparatide, a recombinant fragment of human parathyroid hormone (PTH 1-34) that stimulates new bone formation and reduces fracture risk in adults with osteoporosis. It is administered as a once-daily subcutaneous injection for a maximum of 24 months and is particularly effective for patients at high risk of fracture, including those with glucocorticoid-induced osteoporosis.
Quick Facts
Key Takeaways
- Terrosa (teriparatide) is a bone-building (anabolic) injection used to treat osteoporosis in adults at high fracture risk.
- It is injected once daily under the skin (thigh or abdomen) at a fixed dose of 20 micrograms for up to 24 months total lifetime use.
- The most common side effects are limb pain, nausea, headache, and dizziness; most are mild and temporary.
- After stopping Terrosa, patients typically switch to an antiresorptive drug (such as a bisphosphonate) to preserve bone gains.
- Must be stored refrigerated (2–8 °C), never frozen, and each cartridge must be discarded 28 days after first use.
What Is Terrosa and What Is It Used For?
Terrosa belongs to a class of medications called parathyroid hormone analogues. Its active ingredient, teriparatide, is a recombinant form of the first 34 amino acids of human parathyroid hormone (PTH 1-34). Unlike most osteoporosis treatments that work by slowing bone breakdown (antiresorptive agents), teriparatide is an anabolic agent that directly stimulates the formation of new bone tissue.
When administered as a daily subcutaneous injection, teriparatide activates osteoblasts — the cells responsible for building new bone. This preferential stimulation of bone formation over bone resorption results in a net increase in bone mass and improvement in bone microarchitecture. Clinical trials have demonstrated that teriparatide increases bone mineral density (BMD) at the lumbar spine by approximately 9–13% and at the femoral neck by 3–6% over an 18-month treatment period.
Terrosa is a biosimilar of Forsteo (the originator teriparatide product), approved by the European Medicines Agency (EMA) after demonstrating comparable quality, safety, and efficacy. It is indicated for the treatment of:
- Postmenopausal osteoporosis — in women at high risk of fractures who have not responded to, or cannot tolerate, other osteoporosis treatments
- Osteoporosis in men — particularly those at increased fracture risk
- Glucocorticoid-induced osteoporosis — in patients receiving sustained systemic corticosteroid therapy who are at high risk of fractures
The landmark Fracture Prevention Trial (Neer et al., New England Journal of Medicine, 2001) demonstrated that teriparatide reduced the risk of new vertebral fractures by 65% and non-vertebral fractures by 53% compared to placebo in postmenopausal women with prior vertebral fractures. These findings have been confirmed in subsequent studies, including the VERO trial, which showed teriparatide was superior to risedronate in preventing new vertebral and clinical fractures.
The International Osteoporosis Foundation (IOF) and the European Society for Clinical and Economic Aspects of Osteoporosis (ESCEO) recommend teriparatide as a first-line option for patients at very high fracture risk, including those with severe or multiple vertebral fractures, very low bone density, or recent fragility fractures.
What Should You Know Before Taking Terrosa?
Before starting treatment with Terrosa, your doctor will assess your overall health, bone density, fracture history, and blood calcium levels. It is essential to disclose your complete medical history, including all medications you are currently taking, to ensure Terrosa is safe and appropriate for you.
Contraindications
You must not use Terrosa in the following situations:
- Hypersensitivity — allergy to teriparatide or any of the excipients
- Pre-existing hypercalcemia — if you already have elevated blood calcium levels
- Severe renal impairment — significantly reduced kidney function (eGFR <30 mL/min)
- Bone malignancies — skeletal cancers, including bone metastases from other primary tumours
- Unexplained elevated alkaline phosphatase — which may indicate Paget’s disease of bone
- Prior radiation therapy to the skeleton — external beam or implant radiation involving bone
- Pregnancy and breastfeeding — Terrosa must not be used during pregnancy or while nursing
- Open epiphyses — not for use in children or young adults who are still growing
Warnings and Precautions
Discuss the following with your doctor before or during Terrosa treatment:
Hypercalcemia: Teriparatide can increase calcium levels in blood and urine. Symptoms of elevated calcium include persistent nausea, vomiting, constipation, low energy, and muscle weakness. Your doctor will monitor your calcium levels during treatment, particularly during the initial weeks.
Kidney stones: If you have a current or past history of kidney stones (nephrolithiasis), tell your doctor. Elevated urinary calcium may increase the risk of stone formation. Adequate hydration is recommended during treatment.
Moderate renal impairment: If you have moderately reduced kidney function, Terrosa should be used with caution and under close medical supervision, as your kidneys play a key role in calcium regulation.
Orthostatic hypotension: Some patients experience dizziness or a rapid heartbeat after the first few doses. It is advisable to inject Terrosa in a location where you can quickly sit or lie down if you feel lightheaded. This effect typically diminishes with continued use.
The recommended treatment duration of 24 months must not be exceeded. You should not receive more than one 24-month course of teriparatide in your lifetime. This limitation is based on preclinical safety data.
Pregnancy and Breastfeeding
Terrosa must not be used during pregnancy or breastfeeding. If you are a woman of childbearing potential, you should use reliable contraception during treatment. If you become pregnant while using Terrosa, discontinue treatment immediately and contact your doctor. There are no adequate human studies on the effects of teriparatide during pregnancy, and animal studies suggest potential risks to fetal development.
Children and Adolescents
Terrosa must not be used in children or adolescents under 18 years of age, as the safety and efficacy in this population have not been established. Teriparatide should not be used in individuals with open growth plates (epiphyses), as the long-term effects on growing bones are unknown.
Driving and Operating Machinery
Some patients may experience dizziness after injection. If you feel dizzy, do not drive or operate machinery until you feel better. This is most likely to occur during the first few injections and tends to resolve with continued treatment.
Terrosa contains less than 1 mmol (23 mg) of sodium per dose and is therefore considered essentially sodium-free.
How Does Terrosa Interact with Other Drugs?
Teriparatide has a relatively favourable drug interaction profile compared to many other medications. However, because it affects calcium metabolism, certain combinations require careful monitoring. The table below summarises the key interactions healthcare providers should be aware of.
| Interacting Drug | Severity | Effect | Clinical Advice |
|---|---|---|---|
| Digoxin / Digitalis glycosides | Moderate | Teriparatide may transiently increase serum calcium; hypercalcemia predisposes to digitalis toxicity | Monitor serum calcium and signs of digitalis toxicity (nausea, arrhythmias) |
| Calcium supplements | Low | Concurrent use is common and generally recommended, but excessive intake may contribute to hypercalcemia | Follow prescribed calcium and vitamin D doses; do not exceed recommended intake |
| Vitamin D supplements | Low | Often co-prescribed; very high doses may theoretically contribute to hypercalcemia | Take as directed by your doctor; routine monitoring is recommended |
| Bisphosphonates | Low | Concurrent use may blunt the anabolic effect of teriparatide; sequential use is generally preferred | Usually used sequentially rather than simultaneously; discuss timing with your doctor |
| Thiazide diuretics | Low | Thiazides reduce urinary calcium excretion, potentially contributing to hypercalcemia when combined with teriparatide | Monitor serum calcium levels periodically |
Additional Considerations
While the drug interaction profile of teriparatide is relatively limited, it is important to tell your doctor or pharmacist about all medicines you are currently taking, have recently taken, or might take. This includes over-the-counter medications, herbal supplements, and vitamins. Your doctor will determine whether any adjustments are needed.
Teriparatide does not appear to interact significantly with common medications such as antihypertensives, statins, proton pump inhibitors, or most analgesics. It can generally be used safely alongside hormone replacement therapy (HRT) in postmenopausal women, though this combination should be managed by a specialist.
What Is the Correct Dosage of Terrosa?
Terrosa has a fixed daily dose for all adult patients. Unlike many medications, the dose does not need to be adjusted based on body weight, age, or severity of osteoporosis. The simplicity of the dosing regimen helps ensure consistent treatment outcomes.
Adults
Standard Adult Dose
Dose: 20 micrograms (corresponding to 80 microlitres) once daily
Route: Subcutaneous injection into the thigh or abdomen
Duration: Maximum 24 months (lifetime total)
Timing: Inject at the same time each day; can be given with or without food
Your doctor will typically recommend concurrent supplementation with calcium and vitamin D throughout the treatment period and will specify the appropriate daily amounts for you. Adequate calcium and vitamin D intake is essential for teriparatide to work effectively, as the bone-building process requires these nutrients as raw materials.
Each Terrosa cartridge contains 2.4 mL of solution, providing 600 micrograms of teriparatide — sufficient for 28 daily doses of 20 micrograms each. The Terrosa Pen is a reusable, multi-dose delivery device that accepts Terrosa cartridges and uses compatible pen needles (29–31 gauge, 5–12.7 mm length).
Injection Technique
Proper injection technique is important for consistent drug delivery and to minimise discomfort:
- Prepare: Wash your hands. Remove the pen (with cartridge inserted) from the refrigerator. Attach a new needle for each injection.
- Set the dose: Turn the dosing knob clockwise until the arrow symbol appears in the display window, aligned with the indicator line. You will feel a click.
- Clean the site: Choose a spot on your thigh or abdomen and clean the skin as directed.
- Inject: Gently pinch a skin fold. Insert the needle straight into the skin. Press the injection button and hold until the dosing indicator returns to the start position.
- Hold: Keep the needle in the skin for 6 seconds after injection to ensure full dose delivery.
- Remove and dispose: Withdraw the needle slowly. Replace the outer needle cap, unscrew and discard the needle in a sharps container. Replace the pen cap and return the pen to the refrigerator immediately.
Never store the pen with a needle attached. Never share your pen with another person. Do not use the pen to inject any other medication. Do not refill the cartridge or transfer the solution to a syringe.
Children
Terrosa is not approved for use in children or adolescents under 18 years of age. There is no recommended paediatric dose.
Elderly Patients
No dose adjustment is required for elderly patients. Teriparatide has been studied extensively in older adults, including those over 75 years of age, and the standard dose of 20 micrograms daily is appropriate. However, orthostatic hypotension may be more pronounced in older patients, so extra care should be taken during the first injections.
Missed Dose
If you forget an injection or cannot take it at the usual time, inject as soon as possible on the same day. Do not take a double dose to make up for a missed one. Never inject more than once on the same day, even if you missed the previous day’s dose. Simply resume your regular daily schedule the following day.
Overdose
If you accidentally use more Terrosa than prescribed, contact your doctor or pharmacist immediately. Expected effects of overdose include nausea, vomiting, dizziness, and headache. Hypotension (low blood pressure) and hypercalcemia (elevated calcium) may also occur. Treatment is supportive, and serum calcium should be monitored.
What Are the Side Effects of Terrosa?
Like all medicines, Terrosa can cause side effects, although not everyone experiences them. Most side effects are mild to moderate in severity and tend to improve over time as your body adjusts to the treatment. Below is a comprehensive breakdown of reported side effects organised by frequency.
Very Common
Affects more than 1 in 10 people
- Pain in the arms and legs (limb pain)
Common
Affects up to 1 in 10 people
- Nausea
- Headache
- Dizziness
- Elevated blood cholesterol levels
- Depression
- Nerve pain in the legs (sciatica)
- Feeling of weakness
- Vertigo (spinning sensation)
- Irregular heartbeat (palpitations)
- Shortness of breath
- Increased sweating
- Muscle cramps
- Reduced energy and fatigue
- Chest pain
- Low blood pressure (hypotension)
- Heartburn (gastro-oesophageal reflux)
- Vomiting
- Hiatal hernia
- Low haemoglobin or red blood cell count (anaemia)
- Injection site reactions (redness, pain, swelling, itching, bruising, minor bleeding)
Uncommon
Affects up to 1 in 100 people
- Increased heart rate (tachycardia)
- Abnormal heart sounds (cardiac murmur)
- Breathlessness
- Haemorrhoids
- Urinary incontinence
- Increased urinary frequency (polyuria)
- Weight gain
- Kidney stones (nephrolithiasis)
- Muscle and joint pain (some patients have experienced severe cramps or back pain requiring hospitalisation)
- Elevated blood calcium (hypercalcemia)
- Elevated uric acid levels
- Elevated alkaline phosphatase
Rare
Affects up to 1 in 1,000 people
- Reduced kidney function, including renal failure
- Oedema (swelling), mainly of hands, feet, and legs
- Allergic reactions such as breathing difficulty, facial swelling, rash, and chest pain (anaphylaxis in very rare cases)
When to Seek Medical Attention
Contact your doctor immediately if you experience any of the following:
- Signs of a severe allergic reaction: difficulty breathing, swelling of the face or throat, widespread rash, chest tightness
- Persistent nausea, vomiting, constipation, low energy, or muscle weakness (possible signs of hypercalcemia)
- Severe back pain or muscle cramps that affect your daily activities
- Fainting or feeling very faint after injection
- Signs of kidney problems: reduced urine output, swelling in legs, persistent fatigue
Injection site reactions such as mild redness, swelling, or bruising are common and typically resolve within a few days. If these persist or worsen, consult your doctor. Dizziness after injection is most common during the first few doses and usually improves with continued use. If you feel dizzy, sit or lie down until the sensation passes.
If you experience any side effects, including those not listed above, you can report them to your national pharmacovigilance authority (such as the MHRA in the UK, the FDA in the US, or via the EMA in EU member states). Reporting helps monitor the ongoing safety of medicines.
How Should You Store Terrosa?
Proper storage is essential to maintain the effectiveness and safety of Terrosa. Teriparatide is a biological peptide that degrades if exposed to temperatures outside the recommended range.
- Before first use: Store in a refrigerator (2–8 °C). Keep the cartridge in the outer carton to protect from light.
- After first use: Store the pen with the inserted cartridge in the refrigerator (2–8 °C). Return it to the refrigerator immediately after each daily injection.
- Do not freeze: Do not place the cartridge near the freezer compartment. If Terrosa has been frozen, it must not be used.
- 28-day limit: Each cartridge must be discarded 28 days after the first injection, even if it is not completely empty.
- Check before use: Terrosa should be a clear, colourless solution. Do not use it if you see particles, cloudiness, or discolouration.
- Expiry date: Do not use after the expiry date printed on the carton and cartridge (EXP). The expiry date refers to the last day of that month.
Keep Terrosa out of the sight and reach of children. Never store the pen with a needle attached, as this can introduce air bubbles into the cartridge and compromise sterility. Dispose of used cartridges and needles in accordance with local regulations — typically in a puncture-resistant sharps container. Do not dispose of medicines via household waste or through the water supply.
What Does Terrosa Contain?
Active Ingredient
The active substance is teriparatide. Each dose of 80 microlitres contains 20 micrograms of teriparatide. A single cartridge of 2.4 mL contains 600 micrograms of teriparatide (equivalent to 250 micrograms per mL).
Inactive Ingredients (Excipients)
- Glacial acetic acid (concentrated acetic acid)
- Mannitol
- Metacresol (preservative)
- Sodium acetate trihydrate
- Hydrochloric acid (for pH adjustment)
- Sodium hydroxide (for pH adjustment)
- Water for injections
Appearance and Pack Sizes
Terrosa is a clear, colourless solution for injection supplied in glass cartridges. Each cartridge contains 2.4 mL of solution, sufficient for 28 doses. Available pack sizes include:
- 1 cartridge packed in a sealed plastic tray within a carton
- 3 cartridges packed in a sealed plastic tray within a carton
- Terrosa cartridge and pen combination pack (1 cartridge + 1 Terrosa Pen)
Not all pack sizes may be marketed in all countries. The pen and injection needles are not included with individual cartridge packs and must be obtained separately. The Terrosa Pen is a reusable device with a lifespan of two years, compatible with ISO-standard pen needles (29–31 gauge, 5–12.7 mm).
Frequently Asked Questions About Terrosa
Terrosa (teriparatide) is used to treat osteoporosis in adults at high risk of bone fractures. It works differently from most osteoporosis drugs by actively building new bone rather than simply slowing bone loss. It is prescribed for postmenopausal women, men with osteoporosis, and patients with glucocorticoid-induced osteoporosis.
The maximum treatment duration with Terrosa is 24 months, and this is a lifetime limit — you should not receive more than one 24-month course. After stopping, your doctor will usually prescribe an antiresorptive medication (such as a bisphosphonate) to help maintain the bone density gains achieved with teriparatide.
The most common side effect is pain in the arms and legs (limb pain), which affects more than 1 in 10 users. Other common side effects include nausea, headache, dizziness, elevated cholesterol, fatigue, muscle cramps, and mild injection site reactions. Most side effects are mild and tend to improve with continued use.
Terrosa is injected once daily under the skin (subcutaneously) into the thigh or abdomen using the Terrosa Pen. Attach a new needle, turn the dosing knob until the arrow appears, pinch a skin fold, insert the needle straight in, press the button, hold for 6 seconds, then remove. Use a new needle each time and return the pen to the refrigerator immediately after use.
Store Terrosa in a refrigerator between 2–8 °C. Never freeze it. Keep the cartridge in the outer carton to protect from light. After first use, each cartridge can be used for up to 28 days as long as it is refrigerated. Discard the cartridge after 28 days even if solution remains.
Terrosa and Forsteo both contain the same active substance (teriparatide 20 micrograms per dose) and treat osteoporosis. Terrosa is a biosimilar of Forsteo, meaning it has been shown to have equivalent quality, safety, and efficacy. The key practical difference is the delivery device: Terrosa uses a reusable pen with replaceable cartridges, while Forsteo uses a disposable pre-filled pen. Both are equally effective for treating osteoporosis.
References
This article is based on the following peer-reviewed sources and international medical guidelines:
- European Medicines Agency (EMA). Terrosa – Summary of Product Characteristics (SmPC). Last updated 2022. Available at: ema.europa.eu/en/medicines/human/EPAR/terrosa
- Neer RM, Arnaud CD, Zanchetta JR, et al. Effect of Parathyroid Hormone (1-34) on Fractures and Bone Mineral Density in Postmenopausal Women with Osteoporosis. N Engl J Med. 2001;344(19):1434-1441. doi:10.1056/NEJM200105103441904
- Kendler DL, Marin F, Zerbini CAF, et al. Effects of teriparatide and risedronate on new fractures in post-menopausal women with severe osteoporosis (VERO): a multicentre, double-blind, double-dummy, randomised controlled trial. Lancet. 2018;391(10117):230-240.
- National Institute for Health and Care Excellence (NICE). Teriparatide for the secondary prevention of osteoporotic fragility fractures in postmenopausal women. Technology Appraisal TA161. 2023.
- Kanis JA, Cooper C, Rizzoli R, Reginster JY. European guidance for the diagnosis and management of osteoporosis in postmenopausal women. Osteoporos Int. 2019;30(1):3-44.
- International Osteoporosis Foundation (IOF). IOF-ESCEO Framework for the Management of Osteoporosis. 2024.
- World Health Organization (WHO). WHO Model List of Essential Medicines. 23rd edition, 2023.
- British National Formulary (BNF). Teriparatide: indications, dosage, and side effects. 2025.
Editorial Team
This article has been written and reviewed by qualified medical professionals to ensure accuracy and adherence to international clinical guidelines.
iMedic Medical Editorial Team — specialists in clinical pharmacology, endocrinology, and evidence-based medicine.
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