How does isoniazid work on dogs? - briefly
Isoniazid works by inhibiting mycolic acid synthesis in bacterial cells, which are essential for their survival and growth. This medication specifically targets Mycobacterium tuberculosis, effectively treating canine tuberculosis in dogs.
How does isoniazid work on dogs? - in detail
Isoniazid, also known as INH, is an antibiotic commonly used in veterinary medicine for the treatment of canine tuberculosis and other mycobacterial infections. Its mechanism of action involves several steps that make it highly effective against these pathogens.
Firstly, isoniazid is a prodrug, meaning it requires activation within the bacterial cell to exert its antimicrobial effects. Once inside the Mycobacterium cell, isoniazid undergoes catalytic activation by the enzyme KatG, also known as mycothiol-dependent catalase-peroxidase. This activation process converts isoniazid into an active form that can interfere with essential bacterial processes.
The primary target of activated isoniazid is the mycolic acid synthesis pathway in the bacterial cell wall. Mycolic acids are long-chain fatty acids unique to the cell walls of mycobacteria, including those that cause tuberculosis. Isoniazid inhibits the enzyme InhA (enoyl-ACP reductase), which is crucial for the synthesis of mycolic acids. By blocking this enzyme, isoniazid prevents the formation of a functional cell wall, leading to bacterial cell death.
In addition to its direct inhibitory effect on InhA, isoniazid also interferes with other essential metabolic processes in Mycobacterium cells. It can disrupt the electron transport chain, affecting the bacteria's ability to generate energy efficiently. This secondary effect contributes to the overall antimicrobial activity of isoniazid, further impairing the bacterial cell's viability and growth.
It is important to note that while isoniazid is effective against mycobacteria, it has limited activity against other types of bacteria. This specificity is due to the unique activation process required for isoniazid to become active and the presence of InhA as a target enzyme in Mycobacterium species but not in most other bacterial pathogens.
In summary, isoniazid works on dogs by being activated within the mycobacterial cell, inhibiting the synthesis of mycolic acids essential for the bacterial cell wall, and disrupting energy metabolism. These combined effects make isoniazid a potent antibiotic for treating canine tuberculosis and other mycobacterial infections.