Aclasta

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Aclasta

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Medically reviewed

Rosario Oropesa

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Aclasta

Property Description
Active ingredient Zoledronic acid
Form Solution for infusion
Pharmacological class Nitrogen-containing bisphosphonate
General purpose Regulator of bone metabolism
Origin Synthetic (Imidazole derivative)

What is the Composition and Class of Aclasta?

Aclasta is a prescription-only medicine whose fundamental active ingredient is Zoledronic acid, a chemically synthesized compound. This substance belongs to the high-level pharmacological class of bisphosphonates, specifically categorized as a potent nitrogen-containing bisphosphonate. Zoledronic acid is used to slow down bone breakdown and reduce bone loss. The medicine's primary role is thus focused on protecting the skeletal structure.

The Zoledronic acid molecule is characterized by an imidazole derivative structure. This chemical identity positions the drug as a powerful anti-resorptive agent that works selectively within the skeletal system. Its high efficacy and sustained action are recognized for maximizing compliance and therapeutic impact.


What is the Pharmaceutical Form of Zoledronic Acid?

The dosage form of Aclasta is a sterile, clear solution for infusion, meaning the active ingredient is dissolved in an aqueous base, which typically includes excipients like Mannitol and Sodium Citrate to ensure stability. This product is a single-active ingredient product.

The established route of administration is exclusively Intravenous (IV) delivery, requiring administration directly into a vein. This unique method is a key distinguishing feature of Zoledronic acid formulations for some therapeutic uses, as it ensures the complete and reliable systemic absorption of the drug, allowing it to rapidly reach the targeted bone tissue.


What is the General Therapeutic Purpose of Aclasta?

The general therapeutic purpose of Aclasta is to act as a powerful bone metabolism regulator by maintaining the stability and structural strength of the skeleton. It functions as an anti-resorptive agent that reduces the excessive loss of bone material, which is a typical use scenario when bone turnover exceeds bone formation.

The core benefit is achieved by the drug's selective and high affinity for mineralized bone, where it potently inhibits osteoclastic bone resorption, the process responsible for breaking down bone tissue. This medicine is categorized within the group of compounds used to address bone diseases.

Regulatory References

  1. EMA

What side effects are possible with Aclasta?

Possible Side Effects and Safety Information

Adverse reactions associated with zoledronic acid (Aclasta/Reclast) are classified and communicated by regulatory bodies using established frequency categories and system-organ classes. The official safety profile distinguishes between common, transient effects and rare, serious adverse events.

Frequency-Classified Adverse Reactions

The most commonly reported adverse reactions are often associated with an acute phase reaction, typically occurring within the first three days following administration. These include Pyrexia (fever), classified as Very Common (ge 1/10), and Common (ge 1/100 to < 1/10) effects such as headache, myalgia, arthralgia, and flu-like symptoms.

  • Common systemic effects also include nausea, vomiting, diarrhea, and hypocalcaemia (low blood calcium).

Serious Adverse Reactions and Safety Constraints

The label documents several serious adverse reactions, which are generally considered Rare (ge 1/10,000 to < 1/1,000). These include Osteonecrosis of the Jaw (ONJ) and Acute Renal Failure. There is also a documented risk of Atypical Femoral Fractures, particularly associated with long-term use of bisphosphonates.

Official safety constraints state that the medication is contraindicated in patients with severe renal impairment (creatinine clearance < 35 mL/min), uncorrected hypocalcaemia, and during pregnancy or lactation. The concomitant use of other zoledronic acid products (product duplication) is also restricted by regulatory agencies.

Overdose and Emergency Response

Overdose and When to Seek Help

The officially documented primary manifestation of an Aclasta overdose is profound hypocalcaemia (abnormally low serum calcium levels), often accompanied by hypophosphataemia and hypomagnesaemia. This metabolic disturbance can escalate to severe systemic consequences, including neurological effects such as seizures and tetany. A critical risk documented in regulatory sources is acute renal function deterioration, which has the potential to progress to severe renal failure. Patients with pre-existing severe renal impairment are noted to be at an increased risk of this complication.

Immediate medical attention is required for any clinical signs of hypocalcaemia, especially the development of tetany or seizures. Emergency services must be contacted immediately for any suspected life-threatening scenario. Management is supportive, as regulatory labeling indicates no specific antidote is known for Zoledronic acid overdose.

The official procedure for managing symptomatic hypocalcaemia is the prompt intravenous administration of calcium gluconate or calcium chloride, and potentially magnesium, to correct the electrolyte imbalance. Furthermore, aggressive monitoring of serum electrolytes and renal function (creatinine clearance) is mandated following an overdose.

Therapeutic Uses of Aclasta

Therapeutic Indications

Aclasta is a medication used to treat several conditions that affect bone metabolism. It belongs to a group of medicines known as bisphosphonates, which work by altering the cycle of bone formation and breakdown in the body.

Osteoporosis in Postmenopausal Women and Men

The primary use of Aclasta is the treatment of osteoporosis. This condition causes bones to become thin, fragile, and more likely to break. In postmenopausal women, the decrease in estrogen levels leads to increased bone turnover. In men, osteoporosis can develop due to aging or low levels of testosterone. Aclasta is used to increase bone mineral density and reduce the risk of fractures, including those of the hip, spine, and other sites.

Glucocorticoid-Induced Osteoporosis

Long-term use of glucocorticoids (steroid medications) can lead to significant bone loss. Aclasta is indicated for the treatment and prevention of osteoporosis in men and women who are starting or are on long-term systemic glucocorticoid therapy.

Paget’s Disease of Bone

Paget’s disease is a chronic disorder where the normal process of bone remodeling is disrupted. The bone is broken down and replaced much faster than usual, resulting in a disorganized bone structure that is weak and may be painful or deformed. Aclasta helps to normalize the bone remodeling process, reducing the symptoms and complications associated with this condition.

Benefits of Treatment

Increased Bone Strength

By slowing down the rate at which bone is broken down, Aclasta allows the body’s bone-building cells to work more effectively. This results in an overall increase in bone mass and improved bone strength over time.

Fracture Risk Reduction

The most significant clinical benefit for patients with osteoporosis is the reduction in the incidence of bone fractures. By strengthening the skeletal structure, the medication helps prevent the debilitating effects associated with hip and vertebral breaks.

Management of Bone Turnover

In conditions like Paget’s disease, the medication provides long-term control of bone turnover. This can lead to a reduction in bone pain and prevent further skeletal deformities, improving the patient's quality of life and mobility.

Regulatory References

  1. European Medicines Agency (EMA) product overview

Eligibility and Restrictions for Use

Who can and cannot use Aclasta?

The official eligibility for Aclasta (zoledronic acid) is defined by a set of physiological and clinical restrictions documented in regulatory labeling.

Eligibility Scope Status Constraint/Exclusion
Renal Function Status Contraindicated Patients with severe renal impairment (creatinine clearance < 35 mL/min), due to the risk of renal failure.
Calcium Status Contraindicated Patients with hypocalcemia (low calcium levels in the blood); any disturbances in mineral metabolism must be corrected before treatment.
Pregnancy/Lactation Status Contraindicated Women who are pregnant or breast-feeding are prohibited from use.
Age Status Not Recommended Children and adolescents under 18 years of age are not recommended for treatment (safety and efficacy are not established).
Drug-Specific Restriction Restriction Patients should not receive Aclasta concomitantly if they are also being treated with the higher-dose zoledronic acid product (Zometa, for oncology use).
Allergy Contraindicated Individuals with known hypersensitivity to zoledronic acid, any bisphosphonate, or the product's excipients.

Use of Aclasta is permitted in adults who meet the minimum renal function criteria, are not pregnant or nursing, and have normal calcium levels. Close monitoring is advised for elderly patients and those with risk factors for renal impairment.

What should I know about interactions with other medicines?

Interactions with other medicines and products

This section describes documented interaction patterns for zoledronic acid as stated in official government regulatory labels.

Prohibited Combinations and Drug Class Restrictions

Official regulatory documents strictly classify the co-administration of Aclasta with any other bisphosphonate medicine as contraindicated. This restriction also applies to other products that contain the same active ingredient, zoledronic acid, such as Zometa, which are prohibited due to cumulative exposure risk.

Pharmacodynamic and Additive Effects

Co-administration with certain agents may lead to an additive effect to lower serum calcium (hypocalcemia). This risk is officially documented when Aclasta is used in conjunction with aminoglycosides or loop diuretics.

Renal Clearance and Exposure Risks

Zoledronic acid is not systemically metabolized by Cytochrome P450 (CYP) enzymes, meaning CYP-mediated interactions are not a concern. However, the medicine is eliminated primarily by the kidneys. Caution is indicated when it is administered with nephrotoxic drugs or other medicines that can significantly impact renal function, as this may reduce clearance and increase zoledronic acid exposure. For patients with pre-existing renal dysfunction or advanced age, the risk of renal deterioration is officially documented as heightened when these agents are co-administered.

Administration Constraints

The solution must not be mixed with any infusion solutions containing calcium or other divalent cations due to physical incompatibility.

Mechanism of Action

Targeted Sequestration and Enzyme Inhibition in Bone

Zoledronic acid exhibits a chemical affinity for hydroxyapatite, the mineral component of bone, which leads to the localization of the molecule specifically to active bone surfaces. Once the drug is internalized by the bone-resorbing cell (osteoclast), it acts as an inhibitor of the intracellular enzyme Farnesyl Diphosphate Synthase (FPPS), disrupting the mevalonate pathway that supports essential osteoclast function.


Cellular Dysfunction and Anti-Resorptive Cascade

The inhibition of FPPS prevents the synthesis of isoprenoid lipids, leading to a failure in the modification (prenylation) of small GTPase signaling proteins. This molecular event causes the osteoclast to lose its structural integrity and functional capacity, ultimately triggering its programmed cell death (apoptosis). This cellular consequence yields a sustained anti-resorptive effect by reducing the population of functional bone-dissolving cells.


Physiological Rebalance of Bone Metabolism

The systemic consequence of inactivating and eliminating osteoclasts is a prolonged suppression of the rate of bone breakdown. This action modulates the balance of the skeletal remodeling cycle by reducing the influence of bone breakdown, which alters the bone turnover dynamic. This localized mechanism leads to a generalized physiological outcome: a decrease in the overall rate of bone matrix dissolution.

Dosage and Administration Information

How to Use Aclasta: Official Administration Guidelines

Aclasta (zoledronic acid 5 mg) is administered through a highly controlled, cyclical process. The medicine is supplied as a sterile, clear solution and its approved delivery method is exclusively Intravenous (IV) infusion.


Dosing and Frequency Patterns

The single dose must not exceed 5 mg. The frequency pattern is based on the specific use context:

Indication Labeled Dose Frequency Pattern
Osteoporosis Treatment A single infusion of 5 mg Once yearly
Prevention of Postmenopausal Osteoporosis A single infusion of 5 mg Once every two years
Paget's Disease of Bone A single infusion of 5 mg Single initial treatment

If a dose is missed, it should be administered as soon as feasible, and subsequent annual dosing should be re-scheduled based on the new infusion date.


Procedural and Contextual Requirements

The 100 mL solution is ready for use and requires no further dilution. It must be administered slowly over a duration of no less than 15 minutes to ensure proper delivery.

Patients must be appropriately hydrated prior to administration. The infusion must be delivered via a separate vented intravenous line and must not be mixed with any other medicinal products, especially those containing calcium. Adequate calcium and vitamin D intake is recommended in association with administration.

No dose adjustment is required for older adults (ge 65 years) or in cases of hepatic impairment. For renal impairment, no adjustment is needed if creatinine clearance is ge 35 mL/min. The medicine is not recommended for use in the pediatric population.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Aclasta

Evidence for Use in Osteoporosis and Fracture Prevention

Research has explored zoledronic acid in populations with osteoporosis, relying primarily on large, multinational Randomized Controlled Trials (RCTs). These studies were used in research exploring the use of zoledronic acid in comparison to an inactive treatment, or placebo. The core focus of these trials was to monitor measurements related to the rate of new clinical fractures (such as in the hip, spine, and other non-vertebral bones) over a defined period. Researchers also measured changes in bone mineral density (BMD) at key skeletal sites, which is an outcome related to systemic or functional imbalance in bone metabolism.

Trials reported the measurements of how fracture incidence evolved in the observed groups compared to the placebo groups over the intermediate-term follow-up (typically three years). Similarly, research reports patterns of changes in bone mineral density at the hip and spine during the study period. Dedicated research also examined the use of the drug in men with osteoporosis, with findings reporting patterns of changes in fracture incidence and BMD over the study period.

However, the evidence is limited regarding the use of the drug in certain groups, such as those with severe kidney impairment, as these individuals were typically excluded from the major RCTs. While the core trials followed patients for several years, there is limited information for long-term outcomes, particularly concerning the maintenance of effect extending beyond about six years.


Primary Outcomes Studied in Osteoporosis Trials

This subsection will detail the high-level endpoints that the major studies were designed to evaluate, such as changes in bone mineral density measurements and the incidence of various types of fractures. The studies were designed to evaluate specific outcomes linked to bone health. These included monitoring outcomes related to physical discomfort and functional limitation, which are new fractures. Other key outcomes related to systemic imbalance included the measurement of bone mineral density using specialized scans, with findings contributing to understanding bone structural measures. Finally, research also monitored blood levels of certain bone turnover biomarkers to see how they evolved in the observed populations.


Evidence for Secondary Prevention Following a Hip Fracture

Research has explored zoledronic acid in individuals who have recently experienced a low-trauma hip fracture. This clinical context involves periods of heightened symptom activity and functional limitations. A large, dedicated Randomized Controlled Trial (RCT) was designed to evaluate the impact on clinical outcomes when the drug was administered shortly after surgical repair of the fracture.

This key trial focused on outcomes related to physical discomfort by measuring the rate of subsequent clinical fractures (any fracture occurring after the initial hip injury). Outcomes monitoring physiological strain were also examined, as the trial measured all-cause mortality rates during the observation period. The study monitored how these two outcomes evolved in the treated group compared to the placebo group over approximately two years post-fracture.


Evidence Gaps and Areas of Uncertainty

Findings describe group patterns, and research does not determine whether an individual will respond similarly. Several limitations exist in the broader evidence landscape. For instance, evidence quality varies across studies, and data for certain patient groups, such as those with pre-existing, severe kidney disease, remain insufficient as they were often excluded from the largest trials. Long-term effects, especially for outcomes related to the maintenance of BMD and fracture prevention beyond five to six years, are not fully established by controlled trials. Comparative evidence that directly assesses zoledronic acid against the full range of other approved treatments in head-to-head trials is also limited.

Key Studies & References

  1. Trial of Zoledronic Acid in the Prevention of Fracture After Hip Replacement (ClinicalTrials.gov identifier NCT00046254)
  2. ACLASTA (zoledronic acid) Injection Label (U.S. Food and Drug Administration - FDA)

Frequently Asked Questions (FAQ)

Common questions about Aclasta (FAQ)

Q: Is Aclasta used to treat osteoporosis in men as well as women?

A: Yes, official regulatory documents confirm that Aclasta is indicated for the treatment of osteoporosis in men. This includes its use for increasing bone mass, similar to its established use in postmenopausal women.


Q: What is Paget's disease and how does Aclasta address this condition?

A: Paget's disease of the bone is a condition where bone turnover is abnormally high. Aclasta is indicated for this treatment. The drug's anti-resorptive action is intended to modulate the excessive breakdown of bone and support bone metabolism.


Q: How long after the infusion do flu-like symptoms commonly begin?

A: Official product information states that acute phase reactions, such as fever, chills, and flu-like symptoms, typically occur soon after administration. The majority of these side effects appear within the first three days following the Aclasta infusion.


Q: How long do the common flu-like side effects from Aclasta typically last?

A: These acute phase reactions are generally described in regulatory documents as mild to moderate in intensity. They are generally observed to be transient and are reported to typically resolve within three days of their onset.


Q: Are side effects more common after the first Aclasta infusion than later ones?

A: Yes, regulatory data indicates that the incidence of post-dose symptoms, including muscle pain, fever, and headache, is greatest with the first infusion. These effects are reported to decrease markedly with subsequent, repeated annual treatments.


Q: What can be taken for the headache or fever after Aclasta, based on official recommendations?

A: The official label suggests that over-the-counter pain relievers such as paracetamol (acetaminophen) or ibuprofen can be used to manage these symptoms. These are suggested for managing common post-dose reactions like fever and headache.


Q: Is it common to feel tired or experience joint or muscle pain in the first few days after Aclasta?

A: Yes, official safety information lists myalgia (muscle pain), arthralgia (joint pain), fatigue, and malaise (a general unwell feeling) as Common side effects. These are part of the expected acute reaction shortly after the infusion.


Q: Can the infusion cause temporary pain or swelling at the needle insertion site?

A: Infusion site reactions are listed as a Common side effect. This includes temporary redness, swelling, or pain occurring at the specific location where the needle was inserted during the intravenous procedure.


Q: Is a temporary loss of appetite a known side effect of Aclasta?

A: Decreased appetite is listed as an adverse reaction in the post-marketing or less common reports for the active ingredient, zoledronic acid.


Q: What percentage of patients experience fever or flu-like symptoms after the first dose?

A: Fever (pyrexia) is classified as a Very Common side effect in regulatory documents. This means the event may affect more than 1 in 10 patients (10% or more) after the first infusion.


Q: Does Aclasta have any effect on blood pressure after administration?

A: Regulatory safety information lists both hypertension (high blood pressure) and hypotension (low blood pressure) as Uncommon side effects. These effects are not experienced by the majority of patients.


Q: How would I recognize the potential signs of a severe jaw problem related to Aclasta?

A: Osteonecrosis of the jaw (ONJ) is a rare but serious adverse event reported with this class of medication. Symptoms may include jaw pain or swelling, non-healing sores in the mouth, loose teeth, or visible exposed bone.


Q: Are there any known eye-related side effects, such as blurred vision or pain?

A: Ocular hyperaemia (eye redness) is listed as a Common side effect. Rarer but more severe inflammatory reactions affecting the eye, such as uveitis, episcleritis, and scleritis (pain/inflammation), have also been documented in regulatory safety information.


Q: Is there a long-term risk of unusual bone fractures, such as in the thigh bone, with Aclasta?

A: Atypical subtrochanteric and diaphyseal femoral fractures (unusual thigh bone fractures) have been reported with bisphosphonate use. These are primarily associated with patients receiving long-term treatment for osteoporosis.


Q: Is it possible to have persistent bone, joint, or muscle pain that lasts longer than a week?

A: Severe and occasionally incapacitating bone, joint, and/or muscle pain has been reported with zoledronic acid. The onset of this pain can range from days to months after beginning the medication.


Q: Does Aclasta's effect on the jaw mean I should avoid or delay certain dental procedures?

A: Official warnings state that invasive dental procedures should be approached with caution in patients receiving Aclasta. Starting treatment may be delayed if a patient has unhealed, open soft tissue lesions in the mouth that require an oral procedure.


Q: How long does Aclasta continue to work and provide protection after a single infusion?

A: The effect of the zoledronic acid infusion is sustained. For osteoporosis, clinical trials and subsequent regulatory approval support the recommended dosing interval of once yearly, indicating the sustained duration of the drug’s anti-resorptive effect.


Q: What research evidence exists regarding Aclasta's ability to reduce the risk of future bone fractures?

A: Clinical trials indicate that, compared to placebo, Aclasta showed a reduction in the risk of clinical vertebral fractures and hip fractures over three years. These findings are based on observed group patterns in large studies.


Q: Are there studies on the long-term safety and efficacy of Aclasta use over many years?

A: The efficacy and safety profile of Aclasta have been confirmed in clinical trials for up to six years of continuous annual treatment in some patient groups. Information regarding the maintenance of effects beyond this period is limited by controlled trials.


Q: What happens if a dose is missed or delayed beyond the recommended time frame?

A: Official administration guidelines state that if a dose is missed, it should be administered as soon as feasible. Subsequent annual dosing is to be re-scheduled based on the new infusion date.


Q: Is it possible for the effects of Aclasta to wear off over time?

A: Data from trials where treatment was discontinued show that bone mineral density (BMD) does decrease after stopping treatment. However, BMD generally remains above pre-treatment levels for a period of time, indicating a sustained effect.


Q: Why is adequate hydration important for patients receiving Aclasta?

A: Regulatory documents advise that adequate patient hydration is required to minimize potential renal adverse reactions. This precaution is especially important for patients with pre-existing impaired renal function or other risk factors.


Q: What conditions is Aclasta primarily approved to treat?

A: Aclasta is officially indicated for the treatment and prevention of osteoporosis in postmenopausal women and men, as well as for the treatment of Paget's disease of the bone. It is also approved for the secondary prevention of clinical fractures following a low-trauma hip fracture.


Q: How frequently is the Aclasta infusion typically scheduled for osteoporosis treatment?

A: The required frequency depends on the specific context of use. For the treatment of established osteoporosis, the infusion is typically scheduled once yearly. For the prevention of postmenopausal osteoporosis, the medicine is administered once every two years.


Q: What general preparation steps are recommended before receiving the Aclasta infusion?

A: Official administration guidelines recommend that patients be appropriately hydrated prior to the procedure. It is also recommended that patients ensure they have adequate calcium and vitamin D intake in association with the treatment.


Q: Is it necessary to drink extra fluids before the Aclasta infusion?

A: Yes, official procedural requirements state that patients must be appropriately hydrated before receiving the infusion. This step is required, according to official guidelines, as a precaution to minimize the risk of renal adverse reactions.


Q: Can Aclasta affect kidney function, and if so, what precautions are taken?

A: The drug is eliminated primarily by the kidneys, and official safety information lists acute renal failure as a serious adverse reaction. Precautions include excluding patients with severe renal impairment and ensuring patients are adequately hydrated prior to the infusion.


Q: Are there known interactions between Aclasta and certain types of antibiotics?

A: Official interaction documents note that co-administration with aminoglycosides is a concern. This is because combining them may lead to an additive effect that further lowers serum calcium levels in the blood (hypocalcemia).


Q: Is it safe to take over-the-counter pain relievers like ibuprofen (NSAIDs) with Aclasta?

A: Ibuprofen is suggested to manage the common acute post-dose symptoms like fever and headache. However, caution is indicated when Aclasta is co-administered with nephrotoxic drugs, a class that includes NSAIDs like ibuprofen, especially in patients with existing renal risk factors.

How should Aclasta be stored and disposed of?

How to Store and Dispose of Aclasta

The storage and disposal of Aclasta (zoledronic acid solution for infusion) must strictly adhere to the conditions outlined in the official regulatory labeling.


Storage Requirements

  • Unopened Product: Store the bottle below 30 C and do not freeze the solution. The product must be kept out of the sight and reach of children.
  • Opened Solution: Aclasta is a single-use product. The solution should be used immediately after opening. If necessary, it may be stored for up to 24 hours under refrigeration (2 C to 8 C), but must be allowed to reach room temperature before administration.

Disposal Instructions

Any unused medicine or waste material must not be disposed of via wastewater or household waste. Disposal must be performed in accordance with local requirements for pharmaceutical waste.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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