Submitted by Jim K on Sat, 2007-08-18 08:03

Some patients are prescribed Isoniazid (INH) in their CAP. I thought it would be helpful to have an extract from the patent materials which explains this "novel class of antichlamydial agents." INH has the potential for liver toxicity, so should always be used with regular blood tests for liver function.

Some things of note:

  • In vitro (in the test tube) INH is effective against both the replicating and cryptic stationary phase of Cpn but in vivo needs to be used along with other agents such as metronidazole and NAC.
  • It is effective also against mycobacterial infections, which can be a co-infection along with Cpn, causes similar inflammatory action in the body to Cpn infection, and is even more difficult to test for.
  • It is particularly effective in clearing immune cells, macrophages and monocytes, of Cpn helping to empower the immune system. It is also noted as particularly suitable to clear Cpn from human blood vessels.
  • It is not noted to what degree INH is effective in other tissues (e.g. nervous system tissue, crossing the BBB, etc). Readers, please post any references to these questions in the forums.
  • Niacin, a vitamin, is also effective (INH is a niacin derivative compound)


From patent 6,756,369 June 2004 (underlines added):

A unique class of antichlamydial agents that is effective against the replicating and cryptic stationary phases of Chlamydia (and possibly against some other stages of the cryptic phase) have been identified using the susceptibility tests described herein. This novel class of agents comprises ethambutol and isonicotinic acid congeners which include isoniazid (INH), isonicotinic acid (also known as niacin), nicotinic acid, pyrazinamide, ethionamide, and aconiazide; where INH is most preferred. Although these are currently considered effective only for mycobacterial infections, due in part to currently available [susceptability] susceptibility testing methodologies, it has been discovered that these agents, in combination with other antibiotics, are particularly effective against Chlamydia. It is believed that the isonicotinic acid congeners target the constitutive production of catalase and peroxidase, which is a characteristic of microorganisms, such as mycobacteria, that infect monocytes and macrophages. Chlamydia can also successfully infect monocytes and macrophages.

Using INH to eradicate Chlamydia from macrophages and monocytes subsequently assists these cells in their role of fighting infection. However, these agents appear to be less effective, in vitro, against the cryptic phase. Thus, ethambutol, INH and other isonicotinic acid congeners ideally should be used in combination with agents that target other phases of the chlamydial life cycle. These isonicotinic acid congeners are nevertheless excellent agents for the long term therapy of chronic/systemic chlamydial infection generally, and in particular to chlamydial infection of endothelial and smooth muscle cells in human blood vessels.

INH and its congeners can be used to clear infection from monocytes and/or macrophages. When monocytes and macrophages are infected by Chlamydia, they become debilitated and cannot properly or effectively fight infection. It is believed that, if the chlamydial infection, per se, is cleared from these cells, then the monocytes and macrophages can resume their critical roles fighting chlamydial or other infection(s). Thus, patient responsiveness to combination therapy can be optimized by the inclusion of isonicotinic acid congeners. Accordingly, one aspect of the invention provides a specific method for reempowering monocytes or macrophages that have been compromised by a Chlamydia infection and, in turn, comprise treating the infection in other sites. Such compromised macrophages or monocytes can be activated by treating the chlamydial infection by contacting the infected macrophages and/or monocytes with an antichlamydial agent.