Overview of Zyloric 100

Quick Facts

Property	Description
Active ingredient	Allopurinol
Form	Tablet (Oral Formulation)
Pharmacological class	Xanthine Oxidase Inhibitor (XOI)
Common use	Uric acid reduction (Hypouricemic effect)
Origin	Synthetic compound

Identity and Classification: What Type of Medicine is Zyloric 100?

Zyloric 100 is a specific prescription-only medicine brand name whose active component is the synthetic compound Allopurinol, manufactured by Aspen Pharma. This medication is clinically recognized as a xanthine oxidase inhibitor (XOI), a highly specific pharmacological class used for managing elevated uric acid levels. Allopurinol is a purine metabolism inhibitor used to reduce the production of uric acid. The classification as an XOI distinguishes it from common pain relievers because its action targets the underlying chemistry, not just the resulting discomfort.

Composition and Delivery: The Zyloric 100 Tablet Form

Zyloric 100 is supplied as an oral formulation—specifically, a tablet containing 100 mg of the active ingredient Allopurinol. This form is designated for oral administration and systemic absorption, ensuring the medication enters the bloodstream to perform its function. The tablet is a single-ingredient product, containing only Allopurinol and solid excipients necessary for the tablet structure. This 100 mg strength of Zyloric is typically used to initiate treatment or for maintenance in patient groups requiring lower, carefully monitored dosing.

General Purpose: Why Zyloric is Used

The primary general purpose of Zyloric 100 is to achieve a consistent hypouricemic effect, which is the medical term for reducing the amount of uric acid the body produces. This action is the core of its therapeutic value. The medication achieves this through its basic mechanism of effect as a xanthine oxidase inhibitor, blocking the enzyme responsible for creating uric acid. Allopurinol is an agent for long-term reduction of elevated serum uric acid levels. The medication's general benefit is derived from this crucial uric acid synthesis reduction, helping to stabilize levels in the blood.

What side effects are possible with Zyloric 100?

Official Safety Profile and Adverse Reactions

The safety profile of Zyloric 100 (Allopurinol) is classified based on official regulatory data, which organizes potential adverse reactions by frequency and the body system affected.

Common reactions (occurring in 1% to 10% of patients) primarily include skin rash, nausea, and vomiting. These are classified as Dermatological and Gastrointestinal disorders within System-Organ Classes (SOC).

Serious Adverse Reactions and Population-Specific Safety

Regulatory documents highlight the risk of Serious Adverse Reactions (SARs), which are uncommon to rare but clinically significant. These include Allopurinol Hypersensitivity Syndrome (AHS), also known as DRESS, and Severe Cutaneous Adverse Reactions (SCARs) like Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN). These rare, severe reactions involve the skin, liver, and other internal organs.

Classification	Examples of Reactions
Uncommon	Hypersensitivity reactions, abnormal liver function tests
Rare	SJS/TEN, Hepatitis, severe hepatic necrosis
Very Rare	Aplastic anaemia, severe bone marrow depression

Population-specific safety notes exist for patients with renal or hepatic impairment, for whom reduced maintenance doses are advised due to altered drug clearance. Furthermore, the risk of serious skin reactions is officially noted to be higher in patients with renal impairment and in specific populations (e.g., Han Chinese, Thai, or Korean descent) who may carry a certain genetic marker.

Time-Related Safety Patterns

The official label states that an increase in acute gout attacks is commonly reported during the early stages of treatment as the body adjusts to reduced uric acid levels. Similarly, the risk of severe hypersensitivity is noted to be highest during the first few months of therapy and requires discontinuation at the first sign of a rash.

Overdose and Emergency Response

Overdose and When to Seek Help for Zyloric 100

Any known or suspected overdosage of Zyloric 100 (Allopurinol) requires that patients seek immediate medical attention. The official regulatory profile identifies the most frequently reported manifestations following an acute, massive ingestion. These initial presentations commonly include systemic symptoms such as nausea, vomiting, and diarrhea, which may be accompanied by dizziness.

Documented Severe Outcomes

The primary severe toxicity documented in regulatory labeling is nephrotoxicity, which can progress to renal failure. This outcome is associated with massive ingestion and results from the precipitation of Allopurinol metabolites, specifically xanthine and hypoxanthine, within the renal tubules. The regulatory information also notes that overdosage risks may be increased or more severe in patients with existing renal impairment due to reduced drug clearance.

Emergency Management and Monitoring

Management of overdosage is symptomatic and supportive. Regulatory documents state explicitly that no specific antidote is known for Allopurinol. Procedural management includes maintaining adequate hydration to ensure high urine output. In situations of established toxicity, haemodialysis is documented as a measure capable of efficiently removing both the active drug and its metabolite, oxipurinol. Close clinical and laboratory monitoring, with particular focus on renal function, is required.

Therapeutic Uses of Zyloric 100

What Zyloric 100 treats: main uses and benefits

Zyloric (allopurinol) is a medicine used across therapeutic domains where additional symptomatic support is needed. It is commonly used to manage conditions involving elevated uric acid, known as hyperuricemia.

Zyloric helps manage the symptoms of gout—a condition characterized by periods of heightened symptoms, including joint pain and systemic or localized discomfort. It also supports the patient during clinical scenarios such as preventing the formation of certain kidney stones (uric acid lithiasis) and managing high uric acid that may arise during certain cancer treatments (hyperuricemia secondary to chemotherapy).

By lowering uric acid levels, Zyloric is relevant for easing the symptoms that interfere with daily comfort. It contributes to easing the overall symptom load and supports patients during episodes of heightened discomfort. In these contexts, the medication may assist with maintaining functional stability.

Quick Fact: May Assist with Localized Discomfort

Regulatory References

NIH MedlinePlus Drug Information

Eligibility and Restrictions for Use

Zyloric 100 (allopurinol) is a prescription medicine whose use is governed by formal eligibility rules documented by regulatory authorities. Certain patient populations are absolutely excluded, while others require special caution.

Formal Exclusions (Contraindications)

Category	Restriction
Allergy	Patients with a known hypersensitivity to allopurinol or any excipients must not use the medicine.
Severe Reactions	Contraindicated in individuals with a history of severe cutaneous adverse reactions (e.g., SJS, TEN, DRESS) linked to allopurinol.

Conditional Use and Restrictions

Treatment must not be initiated during an acute attack of gout. It is also not recommended for treating asymptomatic hyperuricemia. Eligibility is further restricted by patient health and demographics:

Organ Function: Use requires reduced doses and careful medical oversight in patients with impaired renal or hepatic function.
Age: Use is generally not recommended for pediatric patients unless treating hyperuricemia secondary to malignancy or specific enzyme disorders. Older adults require conservative dosing due to potentially decreased organ clearance.
Pregnancy/Lactation: Use is not recommended during pregnancy or breastfeeding, as the drug and its metabolite are excreted in human milk, and risks must be weighed against necessity.

These official regulatory statements define the boundaries for appropriate use and ensure the medicine is restricted to approved populations.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Regulatory documents outline specific restrictions and conditions for combining Zyloric 100 (Allopurinol) with certain other products, primarily due to altered drug clearance or increased risk of adverse reactions.

Restricted and Prohibited Combinations

Classification	Interacting Medicine(s)	Official Restriction	Regulatory Basis
Prohibited	Pegloticase	Allopurinol must be discontinued during treatment.	FDA
Dose Reduction Mandated	Azathioprine / Mercaptopurine	Mandatory dose reduction of the interacting drug to approximately one-third or one-fourth is required.	EMA / FDA

Pharmacokinetic and Pharmacodynamic Interactions

Co-administration with Allopurinol may increase the systemic exposure of several agents, including Didanosine and Cyclosporine, due to reduced clearance of these drugs. This interaction necessitates close monitoring. The use of Uricosuric Agents (such as Probenecid) can conversely reduce the activity of Allopurinol's active metabolite, Oxipurinol, by accelerating its excretion.

Specific pharmacodynamic interactions include an increased frequency of skin rash when combined with Ampicillin or Amoxicillin. The co-administration of Thiazide Diuretics in patients with decreased renal function is officially associated with an increased risk of severe hypersensitivity reactions.

For Aluminum Hydroxide antacids, a time-based separation of administration is required to prevent interference with Allopurinol absorption.

Mechanism of Action

Targeted Inhibition of Purine Synthesis

The drug's mechanism of action is confined to inhibiting the synthesis of uric acid through targeted interaction with the enzyme Xanthine Oxidoreductase (XOR), which is crucial for purine breakdown. The parent compound, Allopurinol, acts as a competitive inhibitor, and its long-acting metabolite, Oxypurinol, provides the majority of the effect through mechanism-based inhibition, tightly binding to the enzyme's active site. This mechanism blocks the biochemical cascade that produces uric acid, which determines the drug's observed physiological consequence.

Metabolic Rerouting and Mechanistic Scope

This inhibition results in a mechanistic cascade utilizing the prolonged half-life of Oxypurinol (up to 30 hours) to enable sustained enzyme suppression. By blocking the conversion of hypoxanthine and xanthine, the pathway reroutes these more water-soluble purine precursors. This systemic change alters the ratio of excreted purines, resulting in a sustained reduction of uric acid concentration in the circulation. The mechanism is strictly confined to inhibiting synthesis and lacks direct molecular interaction with inflammatory mediators or pathways that confer analgesia. The resulting physiological consequence is gradual and does not facilitate rapid crystal dissolution or immediate inflammatory response modulation.

Dosage and Administration Information

How Zyloric (Allopurinol) is Used

The general principles of Zyloric use generally involve oral administration and a progressive dose-titration strategy. Zyloric 100 is an oral tablet formulation of the active ingredient allopurinol, although an intravenous (IV) form is available for patients who cannot tolerate oral therapy or require use during specific medical treatments.

Administration and Dosage Regimens

Zyloric tablets are typically taken once daily, administered after a meal to enhance tolerance. A key aspect of administration is the maintenance of adequate hydration, to ensure a daily urinary output of at least 2 liters in adults. If a scheduled dose is missed, the standard approach is to skip the missed dose and resume the regular schedule without taking a double dose.

For chronic conditions, therapy often begins with a low starting dose of 100 mg once daily for adults with normal kidney function. The dose is then gradually titrated upward, often in increments of 100 mg weekly, until the target serum uric acid level is achieved. Maintenance dosages commonly range between 200 mg and 600 mg daily, with doses exceeding 300 mg taken in divided doses to improve absorption and tolerance.

Special Population Instructions

Significant dose reductions are utilized for patients with impaired kidney function. For these individuals, the initial dose may be as low as 50 mg daily, or the medicine may be given at extended intervals. Pediatric use is restricted to specific indications, such as hyperuricemia associated with malignancy, with dosing based on weight.

Recent Clinical Evidence

Research evidence / Overview of studies for Zyloric 100

Evidence for Use in Chronic Gout and Hyperuricemia

A large body of research, including numerous Randomized Controlled Trials (RCTs) and comprehensive meta-analyses, has been conducted to explore the effects of Zyloric’s active component, allopurinol, in adults managing chronic gout and elevated serum urate (SUA) levels. Researchers designed studies to monitor biomarker shifts, tracking the proportion of participants who reached and maintained a target SUA level over defined intervals. Research describes measurements of a decrease in SUA concentrations in the observed populations. Maintaining lower SUA levels was observed alongside a lower reported frequency of gout flares compared to control groups over time. Furthermore, studies monitored the change in size of tophi, which are hard uric acid deposits. Findings describe patterns observed in the studies related to the physical size of these deposits and how they may change over the period of observation.

Evidence for Preventing High Uric Acid During Cancer Therapy

Research focused on conditions associated with acute or disruptive episodes, particularly those where high uric acid levels may arise during certain cancer treatments, such as leukemia and lymphoma. These investigations primarily involved comparative trials where the medicine was evaluated against other options during the acute phase of chemotherapy. The main outcomes describing episodic or acute changes that were monitored included the speed of SUA reduction and the rate of development of serious complications like Acute Uric Acid Nephropathy (AUAN). Studies report how symptoms evolved in the observed populations, indicating that the medicine was studied for its role in maintaining SUA levels during the high-risk chemotherapy period.

What Remains Uncertain in the Research Record

Despite the extensive research, the evidence highlights what is still uncertain:

Non-Gout Outcomes: The potential for the medicine to affect non-gout-related outcomes monitoring physiological strain or stress, such as cardiovascular events, remains an area where findings were mixed across various studies, requiring further clarity. Certainty remains low on whether the medicine influences these outcomes outside of the established indications.
Kidney Disease Progression: Evidence is limited on whether the medicine influences the progression of underlying chronic kidney disease (CKD) when used solely for asymptomatic elevated uric acid.
Long-Term Comparative Evidence: While the medicine has been observed in long-term observational settings, comparative evidence is lacking for many years when comparing Zyloric to newer treatment options in terms of definitive, decades-long patient outcomes.

Frequently Asked Questions (FAQ)

Common questions about Zyloric 100 (FAQ)

Q: How quickly can I expect Zyloric 100 to start working?

Official information indicates that Zyloric (allopurinol) begins to exert its action relatively quickly after starting treatment. The onset of its effect in reducing uric acid production is typically described as occurring within 2 to 3 days when taken orally, according to drug information.

Q: Is it normal to have a gout flare when first starting Zyloric 100?

Yes, regulatory documents note that an increase in acute attacks of gout has been commonly reported during the early stages of allopurinol administration. Official safety information notes this is a commonly reported occurrence as the body adjusts to reduced uric acid levels.

Q: How long do people usually need to take Zyloric 100?

For chronic conditions such as gout, the use of Zyloric is often intended to be a long-term strategy. Official guidance indicates that if the medicine is working to maintain target uric acid levels, it is often utilized for long-term management to maintain the target uric acid level.

Q: Does Zyloric 100 affect fertility or have implications for pregnancy?

Regarding fertility, regulatory documents state there is no evidence to suggest that allopurinol reduces fertility in men or women. Official guidance indicates that use during pregnancy or breastfeeding is generally not recommended, as the drug and its metabolite are known to be excreted in human milk.

Q: Can Zyloric 100 interact with common vitamins or supplements?

Yes, the official product information outlines the importance of discussing all other medicines, including any non-prescription vitamins or herbal supplements, with a healthcare provider. This is necessary because of the potential for certain interactions.

Q: Why do doctors check creatinine clearance before prescribing Zyloric 100?

Creatinine clearance is a key measurement used to assess kidney function. Regulatory documents mandate dose reductions for patients with impaired renal function, and this measurement is used to help inform the appropriate starting dose and any required dose adjustments.

Q: Is Zyloric 100 safe for people with a history of heart problems?

While individual risk is determined by a prescriber, official guidance for managing gout often references studies that suggest allopurinol may be an initial treatment option for people with gout who also have cardiovascular disease.

Q: How soon after a gout flare can Zyloric 100 treatment be started?

Regulatory information advises that Zyloric treatment must not be initiated during an acute attack of gout. Some sources indicate that when treatment is initiated soon after a flare has subsided, it may be given alongside anti-inflammatory therapy.

Q: Can Zyloric 100 cause kidney stones or help prevent them?

Zyloric is indicated for specific conditions related to kidney stone formation. It is used to prevent the formation of certain uric acid kidney stones and for reducing uric acid in patients with recurrent calcium oxalate calculi with hyperuricosuria (high uric acid in the urine).

Q: Are there any dietary restrictions while taking Zyloric 100?

The most important instruction regarding use is maintaining adequate hydration, often advised as a daily urinary output of at least 2 liters. While the drug is officially recommended to be taken after a meal, specific food exclusions beyond general gout management are not typically detailed in the official drug label.

Q: Is Zyloric 100 available over the counter?

No, Zyloric (allopurinol) is classified as a prescription-only medicine. Access to the drug requires a formal prescription from a licensed healthcare provider.

Q: Are there alternatives to Zyloric 100 for lowering uric acid?

Yes, official regulatory discussions often refer to other urate-lowering therapies (ULTs) that act differently than Zyloric. These alternatives, such as febuxostat or probenecid, are typically considered when allopurinol is inappropriate or does not achieve the desired uric acid target.

Q: Can Zyloric 100 cause drowsiness or affect driving?

Drowsiness is listed as a potential side effect of Zyloric. Official regulatory advice suggests avoiding driving or operating heavy machinery until you know how the medication affects you personally.

Q: Is it safe to take Zyloric 100 if I have liver problems?

Zyloric may be used in patients with liver problems, but official warnings note that allopurinol may cause hepatotoxicity (liver damage). Regulatory documents note that patients with pre-existing liver disease should have their liver enzymes monitored periodically during therapy.

Q: What kind of monitoring or tests are required while taking Zyloric 100?

Regulatory documents state that regular blood tests are required to monitor the effect of Zyloric. These tests typically check for uric acid levels and evaluate both liver and kidney function (including liver enzymes and creatinine), especially during the initial stages of treatment.

Q: Why does the packaging sometimes say Zyloric is for secondary hyperuricemia?

This term refers to elevated uric acid levels that occur as a result of another medical condition or treatment. Official documents indicate Zyloric is specifically indicated for managing hyperuricemia that is secondary to certain cancer treatments or malignancies.

Q: Does Zyloric 100 have any known interactions with alcohol?

Official drug information advises that alcohol can increase drowsiness and other potential nervous system side effects associated with allopurinol. Regulatory information advises individuals to discuss the use of alcohol with a healthcare provider.

Q: Can Zyloric 100 affect my immune system?

While Zyloric is not an immunosuppressant drug, regulatory documents note important interactions with certain immune-related medications. Specifically, a mandatory dose reduction is required when combined with drugs like azathioprine or mercaptopurine, which affect the immune system.

Q: What is the difference between Zyloric 100 and Febuxostat (a different gout drug)?

Both drugs are classified as urate-lowering therapies (ULTs) used for gout. Regulatory documents distinguish them by noting that they are separate chemical entities with different safety profiles that may affect suitability for certain patient groups.

Q: What is the goal uric acid level when taking Zyloric 100?

Official clinical guideline summaries generally suggest aiming to maintain a serum urate (SUA) level below 6.0 mg/dL for most patients receiving treatment.

Q: Is it common to feel tired or fatigued on Zyloric 100?

Drowsiness is listed as a potential side effect in official product information. Additionally, feeling extreme tiredness or fatigue is noted to be a possible sign that warrants medical review, as it may be linked to a rare but serious reaction.

Q: If Zyloric 100 doesn't seem to be lowering my uric acid, what are the next steps?

If the uric acid target is not met, official information notes that the dose can typically be titrated upward (increased) over time. If the target still cannot be achieved, the use of an alternative urate-lowering therapy may be a consideration.

Q: Is Zyloric 100 for asymptomatic hyperuricemia?

Official regulatory prescribing information explicitly states that Zyloric treatment is not recommended for asymptomatic hyperuricemia, which is elevated uric acid levels without symptoms of gout or other related conditions.

How should Zyloric 100 be stored and disposed of?

Storage and Disposal of Zyloric 100

The storage and disposal of Zyloric (allopurinol) tablets must adhere strictly to regulatory conditions to ensure product stability and environmental safety.

Storage Requirements

Zyloric 100 mg tablets must be stored at a temperature not exceeding 25°C (77°F). The tablets must be kept in the original container or packaging and protected from both light and moisture. For safety, the medicine must be stored out of the sight and reach of children.

Disposal Instructions

Unused or expired Zyloric must not be disposed of via wastewater or household waste. The official instruction is to return any unwanted tablets to a pharmacist or a local pharmaceutical waste disposal program for proper regulated discarding.

Zyloric 100