Rexacin

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Medically reviewed

Laura Arias

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 Rexacin

Property Description
Active ingredient Norfloxacin
Form Film-coated tablet (Oral); Eye drops (Ophthalmic)
Pharmacological class Fluoroquinolone Antibiotic (Quinolone Antimicrobial)
General purpose To kill bacterial pathogens (Bactericidal action)
Origin Synthetic

Defining Rexacin: A Fluoroquinolone Antibiotic

Rexacin is a synthetic broad-spectrum antibacterial agent used to eliminate bacterial pathogens, belonging to the fluoroquinolone class of antibiotics. Its active pharmaceutical ingredient is Norfloxacin, which is formally classified as a Quinolone Antimicrobial. This medicine is not naturally derived; its structure is created in a laboratory, establishing it as a synthetic compound. Norfloxacin's distinct chemical structure, which includes specific fluorine and piperazine moieties, enhances its potency compared to older quinolone drugs.

Composition, Forms, and General Purpose

Rexacin is a single active ingredient product, typically administered orally as a film-coated tablet, a form commonly used for systemic therapy, but it is also prepared as eye drops for localized ophthalmic use. This dual-form availability distinguishes it as a versatile anti-infective agent. The general purpose of this medication is to act as a bactericidal agent, confirming that its role is to actively kill the bacterial pathogens causing an infection. The specific mechanism, which involves Norfloxacin blocking bacterial enzymes essential for DNA replication, is noted for its effectiveness against a wide variety of aerobic bacteria. This established property means the drug is used to help the body reduce the bacterial burden, for instance, during the clearance of common bacterial infections in the genitourinary tract.

What side effects are possible with Rexacin?

Possible Side Effects and Safety Information

The safety profile of Norfloxacin (Rexacin), a fluoroquinolone antimicrobial, is officially documented based on regulatory categorization of adverse reactions and systemic constraints. Adverse effects are classified by the organ systems involved and their frequency of occurrence, as defined in official regulatory documents.

Category Examples of Adverse Reactions
Common (1% to <10%) Nausea, headache, dizziness, abdominal pain, increases in liver enzymes (ALT, AST).
Uncommon (0.1% to <1%) Insomnia, anxiety, depression, blurred vision, palpitation, crystalluria.
System-Organ Classes Gastrointestinal, Nervous System, Musculoskeletal, Psychiatric, Cardiac, and Skin disorders.

Serious adverse reactions are documented and concern multiple body systems. These include potentially disabling and irreversible effects such as tendon rupture (often the Achilles tendon) and peripheral neuropathy (nerve damage), which can manifest shortly after treatment initiation or be delayed by months after cessation. Other serious risks noted in regulatory documents include aortic aneurysm and dissection, hepatic failure, and seizures.

Safety constraints apply to specific populations. The risk of tendon injury is officially increased in older adults and in patients with renal impairment. The drug is contraindicated in individuals with a history of hypersensitivity to any quinolone or prior tendon issues related to this drug class. Co-administration with corticosteroids is officially noted to increase the risk of tendon injury.

Overdose and Emergency Response

Rexacin Overdose and When to Seek Help

Official regulatory information describes specific manifestations and required emergency actions in the event of Norfloxacin (Rexacin) overdose. Due to the potential for severe outcomes, any suspected overdose requires immediate medical attention.


Feature Official Regulatory Statement
Documented Manifestations Documented signs include gastrointestinal haemorrhage, vomiting, diarrhoea, dizziness, tinnitus, and convulsions (seizures).
Severe Outcomes Significant poisoning can lead to serious complications such as acute renal failure and liver damage (hepatic injury).
Required Emergency Action Contact emergency services is mandated for a potentially life-threatening ingestion dose. Seek immediate medical attention.

Management and Monitoring

Management is constrained by the fact that no specific antidote is known, thus relying on symptomatic and supportive treatment. For a potentially life-threatening overdose, regulatory documents state that gastric decontamination, such as gastric lavage, may be considered, along with the use of activated charcoal. Close monitoring is required for any episode of significant poisoning due to the risk of severe systemic injury. No differential overdose manifestations based on patient population are specifically documented in the official management section.

Therapeutic Uses of Rexacin

Rexacin is commonly used to help manage bacterial infections or for prophylaxis. It is generally applied in contexts where short-term symptomatic assistance is needed to support the clearance of the active infection, which contributes to improved comfort and stability.


Therapeutic Use Domains

This medication is a therapeutic option used across domains that involve acute or disruptive symptom patterns within the urinary system and gastrointestinal tract. It is commonly used to manage conditions presenting with acute episodes of cystitis and more systemic infections like pyelonephritis, as well as persistent conditions such as bacterial prostatitis. It is also applied in specialized clinical settings for the management of certain bacterial sexually transmitted infections or for prophylaxis (prevention) of recurrent urinary tract infections.

Rexacin plays a role in managing symptom clusters that interfere with daily comfort, such as the pain and urgency related to inflammatory states in the urinary tract. This use supports the patient during difficult episodes by easing distress and contributes to easing the overall symptom load.

Quick Fact: Relief for Urinary Discomfort The medication is frequently used to manage symptoms related to lower urinary tract infections, including painful urination and the urgent, frequent need to use the restroom.

Eligibility and Restrictions for Use

Rexacin is restricted to use in adults for officially labeled indications. Regulatory documents define several populations for whom the medicine is either contraindicated or requires explicit caution.

Contraindicated Populations

Use is strictly prohibited for any individual with a history of hypersensitivity or allergic reaction to Norfloxacin or any other medicine in the fluoroquinolone class of antimicrobials. The medicine is also contraindicated for patients with a documented history of tendinitis or tendon rupture associated with fluoroquinolone use, and for those with a known history of Myasthenia Gravis.

Age and Physiological Restrictions

Rexacin is not established or contraindicated for use in children and growing adolescents (under 18 years of age). It is also not recommended for use during pregnancy or in women who are breastfeeding. Special caution is required for older adults, patients with pre-existing CNS disorders (such as epilepsy), and those with risk factors for QTc prolongation. Furthermore, patients with severe renal impairment require a restricted, altered use regimen.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Rexacin's interaction profile is officially characterized by its effect on certain metabolic pathways, its ability to bind with specific substances, and various pharmacodynamic potentiations, as documented by regulatory agencies.

Documented Pharmacokinetic Restrictions

Interaction Type Interacting Substance/Class Official Interaction Outcome Regulatory Restriction
Metabolic (CYP1A2 Inhibition) Tizanidine Increased Tizanidine plasma levels Contraindicated
Metabolic (CYP1A2 Inhibition) Theophylline, Caffeine Increased plasma levels; reduced clearance Use with caution; Monitor levels
Chelation (Reduced Absorption) Antacids, Iron/Zinc Supplements Reduced Norfloxacin oral absorption Must be separated by 2 hours
Food/Dietary Milk, Liquid Dairy, General Meals Decreased Norfloxacin absorption Must be separated by 1 to 2 hours

Pharmacodynamic Effects and Cautions

Co-administration with Oral Anticoagulants (e.g., Warfarin) may enhance their effects, requiring the monitoring of Prothrombin Time (INR). Using Rexacin with certain Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) may increase the risk of Central Nervous System (CNS) stimulation. Additionally, co-administration with oral anti-diabetes agents (e.g., Glyburide) may lead to hypoglycemia, a risk officially noted to be more frequent in the elderly population. Co-use with agents known to prolong the QTc interval requires caution due to the risk of additive cardiac effects. Nitrofurantoin co-administration is not recommended due to official in vitro reports of antagonism.

Mechanism of Action

Rexacin (Norfloxacin) is a synthetic antibacterial agent whose mechanism involves the direct and irreversible disruption of the core molecular machinery responsible for maintaining the bacterial genome, resulting in a bactericidal activity.

Targeted Inhibition of Bacterial DNA Enzymes

This mechanism is initiated by Norfloxacin specifically binding to two essential bacterial enzymes, DNA Gyrase and DNA Topoisomerase IV. By stabilizing the complex formed between the enzyme and cleaved DNA, the drug acts as an inhibitor, preventing the necessary re-ligation step and ensuring that the bacterial genome cannot be properly repaired or maintained.

Disruption of Genetic Replication and Cell Division

The molecular failure at the enzyme level leads to the functional disruption of two key processes: DNA replication and chromosome separation. This promotes the accumulation of numerous double-stranded DNA breaks that exceed the capacity of bacterial repair systems, leading to cell death. The potency of this bactericidal mechanism can be biologically constrained by bacterial defense systems, such as mutations in target enzymes (gyrA and parC) or the overexpression of bacterial efflux pumps, which actively expel the drug, lowering the concentration available at the intracellular target sites.

Dosage and Administration Information

How Rexacin is Used: Administration Principles

Rexacin (Norfloxacin) is administered based on parameters that define the route, dose, frequency, and relationship to food. The primary route for systemic therapy is oral administration using the 400 mg film-coated tablet, which is also available in an ophthalmic form for localized use.


Standard Dosing and Frequency

The standard systemic dosing regimen is 400 mg taken twice daily (every 12 hours) for most infections. The total daily dosage must not exceed 800 mg. The duration of use is specific to the condition, ranging from a single 800 mg dose for acute uncomplicated gonorrhea to an extended period of 28 to 42 days for chronic bacterial prostatitis.


Administration Conditions

To optimize absorption, Rexacin must be taken on an empty stomach: at least one hour before a meal or two hours after eating or consuming milk or dairy products. The tablet should be swallowed whole with a full glass of water, and patients are generally advised to drink fluids liberally throughout the course.

Furthermore, the medicine must be taken separately from mineral-containing products. Doses should be separated by at least two hours before or after taking products containing iron, zinc, magnesium, or aluminum (such as antacids or mineral supplements), as these cations can interfere with drug absorption.


Population Adjustments

Dose modification is required for patients with severe kidney impairment. For those with a creatinine clearance (CrCl) of le 30 mL/min/1.73 m^2, the recommended dose is reduced to 400 mg once daily. No specific dose adjustment is required for older adults if their kidney function is normal.

Recent Clinical Evidence

Research evidence / Overview of studies for Rexacin

Rexacin (Norfloxacin) was evaluated in studies of several bacterial conditions, primarily those affecting the urinary and gastrointestinal systems. The evidence base consists mainly of clinical trials and comprehensive scientific reviews that research examined symptom patterns in patients receiving the study treatment and the status of bacterial clearance in patients. This overview summarizes the structure of that research as reported by official regulatory bodies and scientific literature.


Evidence for Urinary Tract Infections (UTI) and Pyelonephritis

The core research for Rexacin was studied in the context of urinary tract infections, including acute cystitis and pyelonephritis. The primary evidence came from short-term randomized controlled trials (RCTs). These studies explored outcomes related to physical discomfort, such as changes in painful or frequent urination, and lab tests to evaluate bacterial clearance. The research considered by regulators included comparative trials that measured non-inferiority against other agents.

Studies reported measurements of bacterial elimination that was observed in a majority of the studied patients within short-term follow-up periods. Research highlights changes measured that described a change in the acute symptoms reported by patients. However, long-term effects are not fully established beyond the initial six months, and evidence requires ongoing evaluation due to concerns that results may not apply equally everywhere given increasing bacterial resistance.


Research on Chronic Bacterial Prostatitis

The research structure for chronic bacterial prostatitis involves specific study designs, primarily consisting of observational studies where comparative evidence is lacking from large, placebo-controlled trials. These studies examined the rate of bacterial clearance from the prostate gland and patient-reported outcomes describing perceived discomfort. Research reports that high rates of bacterial clearance were challenging to document in studies of this condition, and study protocols involved longer observation intervals. The limited information for long-term outcomes means characterizing the sustained success rate or recurrence risk remains difficult.

Frequently Asked Questions (FAQ)

Common questions about Rexacin (FAQ)


Q: How quickly does Rexacin typically start working?

Pharmacological studies described in the official product information indicate that the highest concentration of the active ingredient in the bloodstream is generally reached about one hour after a dose. While the drug starts its activity quickly, the full clinical effect depends on maintaining the treatment for the prescribed duration.


Q: What should I do if I miss a dose of Rexacin?

Official instructions advise that if less than six hours remain before the next scheduled dose, the missed dose should not be taken. Treatment should be continued with the next scheduled dose. Regulatory documents indicate that double doses should not be taken to compensate for a missed dose.


Q: How long can a person usually take Rexacin for?

The length of time Rexacin is taken is determined by the specific type of bacterial infection being treated. This duration can range from a single dose for some acute infections to longer courses, such as up to 42 days for chronic bacterial prostatitis. Treatment is generally kept as brief as possible.


Q: Does Rexacin cause fatigue or drowsiness?

Regulatory safety documents include drowsiness and fatigue among the reported undesirable effects. The potential for these effects suggests caution may be warranted when performing activities that require concentration.


Q: Are there any specific warnings about Rexacin and the heart?

Official warnings note a risk of QTc interval prolongation, which is a change in the electrical activity of the heart. This risk is primarily a concern when Rexacin is used alongside other medications that can also affect the QTc interval. Specific consideration is advised in these situations.


Q: Does Rexacin have a generic version available?

Yes. The active ingredient in Rexacin is Norfloxacin, which is the generic name for the substance. This generic substance is widely described in regulatory texts and may be marketed under various brand names, or as Norfloxacin, depending on the region.


Q: What happens if I suddenly stop taking Rexacin?

Official instructions define the specific duration of therapy. Completing the full duration of therapy is described as important for therapeutic success and to help prevent the development of drug-resistant bacteria. Regulatory documents do not specifically describe withdrawal or cessation symptoms.


Q: Can Rexacin be crushed or chewed?

The official administration instructions require the tablet to be swallowed whole with a full glass of water. It is explicitly noted that the tablets must not be split, crushed, or chewed, as this can interfere with how the medicine is absorbed by the body.


Q: Does Rexacin work immediately, or does it take time to build up?

Studies show that the drug starts working right away, with peak concentrations reached in about one hour. Its bactericidal (bacteria-killing) effect is prompt, but the full resolution of an infection depends on completing the prescribed duration.


Q: Is it necessary to have routine blood tests while taking Rexacin?

While there is no general requirement for mandatory routine blood testing for all patients, official safety documents note that laboratory tests may be necessary. This is especially true to monitor specific side effects like elevated liver enzymes or when the drug is used with certain interacting medications.


Q: Are there any long-term effects associated with taking Rexacin?

Regulatory boxed warnings note that this class of medicine has been associated with serious, potentially prolonged, and disabling adverse reactions. These reactions, such as peripheral neuropathy (nerve damage) or tendon rupture, can be irreversible and may manifest months after discontinuing the drug.


Q: Can Rexacin affect the results of lab tests?

Official safety documents indicate that Rexacin can interfere with certain lab measurements. Specifically, it has been reported to increase values such as liver enzymes (ALT, AST), as well as BUN and serum creatinine levels. Patients taking certain blood thinners require close monitoring of their Prothrombin Time (INR).


Q: Can Rexacin be taken with antacids?

Antacids containing minerals like aluminum or magnesium are instructed to be taken separately from Rexacin. Regulatory instructions mandate a separation period of at least two hours before or two hours after a dose to prevent the antacid from drastically reducing Rexacin's absorption into the bloodstream.


Q: Is it normal to feel a change in mood while on Rexacin?

Official safety information lists potential psychiatric adverse effects, including anxiety, depression, and confusion. Regulatory documents caution that these or more severe effects, like psychotic reactions, have been reported in some patients.


Q: Is it true that Rexacin can cause dizziness?

Yes, according to official regulatory safety documents, dizziness is listed as a common adverse reaction associated with Rexacin use.


Q: Can Rexacin be used by people with liver disease?

The drug has been associated with severe liver problems, including rare fatal cases of hepatic failure. Regulatory documents note that patients who develop signs of liver disease, such as yellowing of the skin or dark urine, should have their clinical status reviewed.


Q: What if I'm taking multiple medications; does Rexacin interact with many of them?

The official interaction profile of Rexacin is complex. It is documented to interact with multiple medication classes, including certain blood thinners, anti-inflammatory drugs, and anti-diabetes agents. Due to the potential for these effects, the use of multiple medications together warrants specific consideration.


Q: Is Rexacin a common cause of dry mouth?

Official safety documents indicate that dry mouth has been reported as an adverse reaction, though it is categorized as a very rare occurrence.


Q: Can Rexacin make you more sensitive to the sun?

Yes, official safety documents list photosensitivity (increased sensitivity to light) and phototoxicity reactions as possible adverse effects. This means that exposure to the sun or UV light may lead to a skin reaction.


Q: Does Rexacin affect blood sugar levels?

Official adverse event sections report that this drug has been associated with changes in blood sugar. Both abnormally low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) have been documented in patients.


Q: Are there any dietary changes recommended when taking Rexacin?

Official administration instructions state that the medicine should be taken on an empty stomach, separated from food, milk, and dairy products. Regulatory guidance also emphasizes drinking sufficient fluids during the course of treatment.

How should Rexacin be stored and disposed of?

The official storage and disposal guidelines for Rexacin (Norfloxacin) are defined by regulatory agencies to ensure product stability and safety.

Storage Conditions

Rexacin must be stored at controlled room temperature, typically between 20 C to 25 C. The product must be protected from moisture, heat, and direct light; therefore, the container should be kept tightly closed in the original packaging. It is an explicit requirement to keep the medication out of the sight and reach of children.

Handling and Disposal

The medicine should not be frozen.

Expired or unused Rexacin should be disposed of via an official drug take-back program when available. If a program is not accessible, the product may be disposed of in household trash by mixing it with an unappealing substance and sealing the mixture in a container, following specific regulatory procedures.

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

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