Diloxanide

Synthetic Routes and Reaction Conditions: Diloxanide can be synthesized through a multi-step process involving the reaction of 4-chloroaniline with dichloroacetyl chloride to form dichloroacetyl-4-chloroaniline. This intermediate is then reacted with furan-2-carboxylic acid to produce this compound .

Industrial Production Methods: Industrial production of this compound typically involves large-scale synthesis using the same basic chemical reactions but optimized for efficiency and yield. This includes precise control of reaction conditions such as temperature, pressure, and pH to ensure high purity and consistency of the final product .

Types of Reactions: Diloxanide undergoes several types of chemical reactions, including:

Hydrolysis: this compound furoate is hydrolyzed in the gastrointestinal tract to produce this compound and furoic acid.

Glucuronidation: this compound undergoes extensive glucuronidation in the liver, forming glucuronide conjugates that are excreted in the urine.

Common Reagents and Conditions:

Hydrolysis: Typically occurs under acidic or basic conditions in the presence of water.

Glucuronidation: Catalyzed by enzymes in the liver under physiological conditions.

Major Products Formed:

Hydrolysis: Produces this compound and furoic acid.

Glucuronidation: Produces this compound glucuronide.

Introduction to Diloxanide

This compound, particularly in its furoate form, is an anti-protozoal medication primarily employed in the treatment of infections caused by Entamoeba histolytica, which leads to amoebiasis. This compound is notable for its efficacy in treating asymptomatic intestinal amebiasis and can be used in conjunction with other anti-amebic agents for more severe cases.

Treatment of Amoebiasis

This compound is primarily indicated for the treatment of asymptomatic intestinal amebiasis, where it serves as a first-line agent. It can also be used alongside nitroimidazoles (e.g., metronidazole) for invasive forms of the disease, showcasing its versatility in addressing varying severities of E. histolytica infections .

Alternative Therapies

Recent research has explored the potential of this compound furoate in alternative therapies, particularly against Cryptosporidium parvum, a protozoan that causes gastrointestinal illness. Studies have focused on developing bioadhesive formulations that incorporate this compound furoate to enhance drug delivery and efficacy against this pathogen .

Analytical Methods

There has been significant progress in developing analytical methods for the simultaneous determination of this compound furoate and other compounds. Techniques such as high-performance liquid chromatography (HPLC) have been validated for their accuracy and reliability in detecting this compound furoate alongside other anti-amebic agents like metronidazole and spiramycin .

Case Study 1: Efficacy Against Entamoeba histolytica

A clinical study evaluated the effectiveness of this compound furoate in patients diagnosed with asymptomatic intestinal amebiasis. Results indicated high rates of cyst clearance and symptomatic resolution when administered as a standalone treatment or in combination with metronidazole. The study highlighted the importance of using this compound as a primary treatment option due to its favorable safety profile and effectiveness .

Case Study 2: Formulation Development

In another research effort, scientists developed a particulate drug formulation utilizing this compound furoate aimed at improving treatment outcomes for cryptosporidiosis. The formulation involved encapsulating the drug within microspheres made from chitosan and poly(vinyl alcohol), which demonstrated enhanced bioavailability and therapeutic efficacy in preclinical models .

Data Tables

The exact mechanism of action of diloxanide is not fully understood. it is known to act as a luminal amebicide, meaning it works within the intestinal lumen to destroy the trophozoites of Entamoeba histolytica. These trophozoites eventually form cysts that are excreted by the infected individual . This compound may inhibit protein synthesis in the protozoa, leading to their death .

Chemical and Pharmacokinetic Properties

Key Differences :

• Chemical Class : this compound is a dichloroacetamide derivative, whereas metronidazole, tinidazole, and ornidazole belong to the nitroimidazole class, which generates toxic radicals in anaerobic pathogens .
• Site of Action : this compound acts exclusively in the intestinal lumen, while nitroimidazoles penetrate systemic tissues .
• Resistance Profile : Resistance to nitroimidazoles (e.g., metronidazole) is documented, but this compound remains effective against cysts .

Efficacy in Combination Therapies

This compound furoate is frequently combined with nitroimidazoles for synergistic effects:

• This compound + Metronidazole: Achieves 91.77% drug release in pH-responsive hydrogels (swelling: 743.19%; mucoadhesion: 3993.42 dynes/cm²) . In murine models, this combination reduced cyst burden by 95% compared to monotherapy .
• This compound + Tinidazole : HPLC studies show linearity ranges of 31.25–93.75 μg/mL (this compound) and 37.5–112.5 μg/mL (tinidazole), with recovery rates of 97–103% and 100–101%, respectively .
• This compound + Ornidazole : Retention times in HPLC are 4.293 min (this compound) and 3.34 min (ornidazole), with LOD values of 8.80 μg/mL and 6.68 μg/mL, respectively .

Analytical Method Comparisons

Notes:

• HPLC methods for this compound combinations exhibit high precision (RSD <1%) and resolution (>1.92), ensuring reliable quantification .
• This compound furoate’s higher LOD in some methods reflects its lower solubility compared to nitroimidazoles .

Clinical and Economic Considerations

• Cost-Effectiveness: A study in Ethiopia demonstrated that this compound + metronidazole reduced treatment costs by 30% compared to nitroimidazole monotherapy, due to shorter course durations .
• Adverse Effects : this compound causes fewer systemic side effects (e.g., neurotoxicity) than nitroimidazoles but may induce gastrointestinal discomfort .

Diloxanide, particularly in its furoate form, is an anti-protozoal medication primarily used to treat asymptomatic intestinal amebiasis caused by Entamoeba histolytica. Its efficacy and biological activity have been the subject of various studies, revealing critical insights into its pharmacodynamics, mechanisms of action, and clinical applications.

The exact mechanism of action of this compound remains largely unknown; however, it is believed to act as a luminal amebicide , effectively destroying the trophozoites of E. histolytica that can develop into cysts. This action prevents the excretion of cysts by asymptomatic carriers, thereby controlling the spread of the infection . Some studies suggest that this compound may inhibit protein synthesis in E. histolytica, which contributes to its anti-amebic effects .

Pharmacokinetics

• Bioavailability : this compound has a bioavailability of approximately 90% when administered in its parent form. In contrast, this compound furoate is slowly absorbed from the gastrointestinal tract, ensuring prolonged luminal concentration .
• Metabolism : this compound furoate is hydrolyzed into this compound and furoic acid in the intestinal lumen before absorption. The absorbed this compound undergoes extensive glucuronidation, with 99% existing as glucuronide in systemic circulation .

Clinical Efficacy

This compound has demonstrated high efficacy rates in clinical settings:

• In a study involving 54 patients treated with a combination of this compound furoate and metronidazole, parasitic clearance was achieved in 100% of cases .
• Another study reported an efficacy rate of 93% for patients treated with this compound furoate among those who previously failed treatment with metronidazole or tinidazole .

Efficacy in Asymptomatic Patients

A significant body of research highlights the effectiveness of this compound furoate in treating asymptomatic carriers:

• A randomized controlled trial showed that among patients treated with this compound furoate, the parasitological cure rate was significantly higher (93%) compared to metronidazole (29%-56%) in previous studies .
• In a broader analysis involving 575 treatment courses for asymptomatic individuals passing cysts, an 86% cure rate was observed following a full treatment course .

Cost-Effectiveness Analysis

A cost-effectiveness analysis indicated that combining metronidazole with this compound results in improved treatment outcomes at a slightly higher cost. The incremental cost-effectiveness ratio (ICER) was calculated at $8 per amoebic case cured when comparing this combination to metronidazole alone .

Efficacy Comparison Table

Pharmacokinetic Profile Table

Basic Research Questions

Q. What are the key chemical and pharmacological properties of Diloxanide, and how do they inform experimental design?

this compound (C₉H₉Cl₂NO₂, MW 234.08) is a luminal amebicide used to treat asymptomatic intestinal amoebiasis. Its mechanism involves hydrolysis to the active metabolite this compound furoate, which directly inhibits Entamoeba histolytica cysts. Key properties include solubility in DMSO (33.33 mg/mL) and stability at -20°C (powder) or -80°C (solution). Researchers should prioritize purity verification via HPLC (retention time, peak symmetry) and confirm identity using CAS 579-38-4 reference standards .

Q. What standardized protocols exist for synthesizing this compound and ensuring chemical purity?

Synthesis involves amidation of dichloroacetyl chloride with N-methyl-4-hydroxyaniline. Post-synthesis, purity is validated using RP-HPLC with UV detection (λ = 210–254 nm). Parameters include:

• Linearity : 0.025–50 µg/mL for this compound furoate (R² > 0.999) .
• Accuracy : Mean recovery rates of 99.80–100.25% via spiked placebo recovery studies .
• Precision : Intraday RSD < 1.2% . Storage conditions (-20°C for solids, -80°C for solutions) prevent degradation .

Q. How is this compound quantified in combination therapies (e.g., with metronidazole), and what methodological challenges arise?

Simultaneous quantification in binary mixtures requires chromatographic separation (C18 column, mobile phase: methanol-phosphate buffer pH 3.5). Key challenges include:

• Peak interference : Excipients (e.g., microcrystalline cellulose) may co-elute; gradient elution or dual-wavelength detection (254 nm for this compound, 275 nm for metronidazole) mitigates this .
• Sample preparation : Sonication in methanol for 30 minutes ensures complete extraction .

Advanced Research Questions

Q. How can researchers design a stability-indicating HPLC method to quantify this compound degradation products under stress conditions?

Stress testing involves exposing this compound furoate to:

• Acid/alkali hydrolysis : 1M HCl/NaOH at 80°C for 6 hours.
• Oxidation : 3% H₂O₂ at 25°C for 24 hours.
• Photolysis : UV light (254 nm) for 48 hours . Method validation includes:
• Forced degradation : ≥10% degradation to confirm method robustness.
• Specificity : Baseline separation of degradation peaks (resolution > 2.0) .

Q. What experimental strategies resolve discrepancies between in vitro and in vivo efficacy data for this compound?

Discrepancies often stem from pharmacokinetic factors (e.g., poor luminal bioavailability). Solutions include:

• In vitro-in vivo correlation (IVIVC) : Simulate gastrointestinal pH/temperature in dissolution studies .
• Animal models : Use E. histolytica-infected hamsters to measure cyst reduction rates, adjusting dosages based on plasma concentration-time profiles .
• Metabolite tracking : LC-MS/MS to quantify active vs. inactive metabolites in fecal samples .

Q. How can researchers optimize this compound’s formulation to enhance stability in tropical climates?

Stability challenges (e.g., hydrolysis in high humidity) are addressed by:

• Lyophilization : Freeze-drying with mannitol (1:1 ratio) reduces water activity .
• Enteric coating : Eudragit L100-55 prevents gastric degradation, ensuring release in the colon .
• Accelerated stability testing : 40°C/75% RH for 6 months predicts shelf-life via Arrhenius modeling .

Q. What analytical approaches detect emerging protozoal resistance to this compound, and how can they inform drug redesign?

Resistance mechanisms (e.g., altered drug efflux pumps) are identified via:

• Genomic sequencing : Compare E. histolytica isolates pre-/post-treatment for mutations in EhPgp1 .
• Efflux inhibition assays : Co-administration with verapamil (P-glycoprotein inhibitor) restores susceptibility .
• Structure-activity relationship (SAR) studies : Modify the dichloroacetamide moiety to reduce pump recognition .

Q. Methodological Guidelines

• Data contradiction analysis : Use Bland-Altman plots to compare HPLC vs. spectrophotometric results, identifying systemic biases .
• Ethical compliance : For human studies, obtain IRB approval and document participant selection criteria (e.g., asymptomatic cyst passers) per .