Draft:Halquinol

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Halquinol

Clinical data
Other names	Chlorhydroxyquinoline
Identifiers
IUPAC name Mixture of: 5-Chloro-8-hydroxyquinoline 7-Chloro-8-hydroxyquinoline 5,7-Dichloro-8-hydroxyquinoline
CAS Number	8067-69-4
PubChem CID	24690
UNII	Z7Z4BX535U

Halquinol is a synthetic mixture of chlorinated hydroxyquinoline derivatives used primarily as an antimicrobial feed additive in veterinary medicine, particularly in swine and poultry, where it helps promote growth and is indicated for the treatment and prevention of intestinal infections caused by pathogens such as Escherichia coli and Salmonella. Its broad-spectrum antimicrobial activity is attributed to its ability to inhibit cellular respiration enzymes of target organisms, conferring antibacterial, antifungal, and antiprotozoal properties, while distinguishing it mechanistically from traditional quinolone antibiotics. Halquinol is approved in multiple countries for veterinary use, with dosing regimens and withdrawal periods tailored to local regulatory requirements, and is generally considered safe with no significant adverse effects noted at recommended concentrations.^[1]

The compound, typically formulated as Halquinol 60 (containing 60% active ingredient), serves as a growth promoter and intestinal health modifier in commercial animal husbandry operations.

Structure and properties

Halquinol belongs to the 8-hydroxyquinoline family of compounds, characterized by its antimicrobial properties against a broad spectrum of microorganisms. The compound exhibits both bacteriostatic and fungistatic activities, making it particularly effective in maintaining intestinal microbiological balance in livestock.

The standard commercial formulation contains 60% active halquinol, typically presented as a fine, free-flowing powder with moisture content maintained below 5% to prevent caking and ensure consistent mixing properties in feed manufacturing processes.

Halquinol is a mixture of chlorinated derivatives of quinolin-8-ol, with its major chemical constituents being 5,7-dichloro-8-hydroxyquinoline (chloroxine) (57–74%), 5-chloro-8-hydroxyquinoline (23–40%), and 7-chloro-8-hydroxyquinoline (0–4%).^[1]: 5

Development

The use of quinoline derivatives in veterinary medicine dates back to the mid-20th century, when researchers began investigating alternatives to traditional antibiotics for growth promotion in livestock. Halquinol emerged as a preferred compound due to its selective antimicrobial activity and reduced tendency to contribute to antibiotic resistance development.

The compound gained widespread acceptance in Asian and European markets during the 1970s and 1980s, particularly in regions with intensive poultry production systems where maintaining gut health became increasingly critical for economic viability.

Mechanism of action

Unlike broad-spectrum antibiotics that indiscriminately eliminate both beneficial and pathogenic microorganisms, halquinol operates through a selective mechanism that preserves intestinal microflora balance. The compound interferes with cellular respiration processes in pathogenic bacteria while allowing beneficial microbes to maintain their ecological niche within the gastrointestinal tract.

This selective activity results in improved nutrient absorption, enhanced immune function, and reduced incidence of digestive disorders without the negative consequences typically associated with antibiotic growth promoters.

Applications in animal husbandry

Poultry production

In commercial poultry operations, halquinol serves multiple functions:

Growth Enhancement: Birds receiving halquinol supplementation typically demonstrate accelerated growth rates, often reaching market weight 3-4 days earlier than non-supplemented controls. This improvement directly translates to reduced housing costs and improved production efficiency.

Feed Conversion Improvement: Studies consistently report 8-12 point improvements in feed conversion ratios, representing significant economic advantages given that feed costs comprise 60-70% of total production expenses in modern poultry operations.

Intestinal Health Management: The compound reduces the incidence of wet litter conditions, digestive upsets, and bacterial enteritis, contributing to overall flock health and welfare.

Heat Stress Mitigation: Research indicates that halquinol supplementation helps maintain growth performance during periods of thermal stress, particularly relevant in tropical and subtropical production environments.

Swine production

While primarily associated with poultry applications, halquinol has found limited use in swine production, particularly in starter feeds for young pigs where intestinal health establishment is critical for subsequent performance.

Aquaculture applications

Some research has explored halquinol's potential in aquaculture settings, though commercial adoption remains limited compared to terrestrial livestock applications.

Regulatory status

The regulatory status of halquinol varies significantly across different jurisdictions. The compound remains approved for use in many Asian countries, including India, where it is widely utilized in commercial poultry production. However, regulatory frameworks in some regions have imposed restrictions or prohibitions on its use, particularly in markets with stringent antibiotic reduction policies.

The Food and Agriculture Organization (FAO) Knowledge Repository] contains extensive documentation regarding the evaluation and appropriate use of feed additives in sustainable livestock production systems.^[1]

Commercial production

Manufacturing standards

Commercial halquinol production typically adheres to stringent quality control standards, including:

• ISO 9001:2015 quality management systems
• ISO 22000:2018 food safety management protocols
• Good Manufacturing Practice (GMP) compliance
• Hazard Analysis and Critical Control Points (HACCP) implementation

Quality specifications

High-quality halquinol formulations maintain active ingredient concentrations within ±2% of declared levels, significantly exceeding standard industry tolerances. Products typically feature:

• 24-month shelf life under appropriate storage conditions
• Moisture content below 5% to prevent degradation
• Consistent particle size distribution for optimal mixing characteristics
• Comprehensive microbiological safety testing

Major producers

India has emerged as a significant producer of halquinol, with companies like Kanad dry chemicals, Mayur Dyes and chemicals, Dr. Katre Premix Lab , establishing themselves as major suppliers in the domestic and export markets. The country's competitive manufacturing costs and established pharmaceutical infrastructure have contributed to its prominence in the global halquinol market.

Research

Extensive field trials and controlled studies have documented halquinol's efficacy across various production systems. Key research findings include:

Growth performance

Multiple studies conducted under commercial conditions have consistently demonstrated significant improvements in:

• Average daily weight gain
• Feed conversion efficiency
• Overall flock uniformity
• Reduced mortality rates

Intestinal health

Microscopic examination of intestinal tissue from halquinol-supplemented birds reveals:

• Enhanced villus height and crypt depth ratios
• Improved intestinal barrier function
• Balanced microbial populations
• Reduced inflammatory markers

Economic impact

Cost-benefit analyses from various production systems indicate positive return on investment, with typical payback periods of 2-3 weeks in broiler production cycles.

Alternatives and sustainability

As the global livestock industry increasingly emphasizes sustainable production practices and reduced reliance on antimicrobial compounds, halquinol occupies a unique position. Its selective mechanism of action and reduced resistance potential make it a viable transitional technology for producers moving away from conventional antibiotic growth promoters.

Alternative approaches under investigation include:

• Organic acids and their salts
• Essential oils and plant extracts
• Probiotics and prebiotics
• Enzyme supplementation
• Immunomodulating compounds

Market

The global halquinol market is concentrated primarily in Asia, with India, China, and Southeast Asian countries representing the largest consumption regions. Market dynamics are influenced by:

• Regulatory changes regarding antibiotic use in animal production
• Consumer preferences for antibiotic-free products
• Economic pressures on livestock production efficiency
• Disease pressure and biosecurity challenges

Pricing

Halquinol pricing varies considerably based on quality specifications, volume requirements, and regional market conditions. Premium formulations from established manufacturers typically command higher prices but offer superior consistency and technical support.

Distribution

The compound is distributed through various channels including:

• Direct manufacturer sales to large integrators
• Regional distributors serving mid-scale operations
• Feed mills incorporating halquinol into commercial feeds
• Veterinary supply chains for smaller producers

Safety considerations

Withdrawal periods

Most regulatory frameworks require specific withdrawal periods before slaughter to ensure negligible residue levels in meat products. These periods vary by jurisdiction but typically range from 3-7 days for poultry.

Handling precautions

Standard occupational safety measures are recommended during handling, including:

• Appropriate personal protective equipment
• Dust control measures during mixing operations
• Proper storage to maintain product stability
• Worker training on safe handling procedures

Environmental impact

Limited environmental persistence and biodegradability characteristics contribute to halquinol's relatively favorable environmental profile compared to some alternative antimicrobial compounds.

References

1. Hall AL, Chicoine A, Boison J, et al. (Prepared by the meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA), 85th Meeting 2017) (2019). Halquinol: Residue Monograph. WHO Food Additives Series. Geneva: World Health Organization and Food and Agriculture Organization of the United Nations. ISBN 978-92-4-166076-1.

Further reading

• de Lourdes Bastos M, Bories G, Brantom P, Galobart J, Gropp J, Marcon F, Pizzo F, Villa RE, Vettori MV (July 2021). EFSA review of Maximum Residue Limits for halquinol in pig tissues as set by JECFA (Report). European Food Safety Authority (EFSA). doi:10.2903/sp.efsa.2021.EN-6692.

External links

• Dr. Katre Premix Lab - Halquinol 60 Product Information