[e-drug] Formulation of Ethambutol with other anti-TB drugs

e-drug
1

E-DRUG: Formulation of Ethambutol with other anti-TB drugs
------------------------------------------------------

Dear Colleagues,

I have recently became aware that the combination formulations of Anti- Tuberculosis Drugs (ATDs) will have all the other three ( rifampicin, pyrazinamide and isoniazid) and ethambutol formulated separately. There are also claims that ethambutol interacts with pyrazinamide. I would like to know if there are any reasons for separately formulating ethambutol and what is the clinical siginificance of such interaction if any. I would like any one who has information to assist me. I am looking forward to a very fruitful discussion. Thank you.

Gauda Timothy Mahlatsi
School of Pharmacy
Faculty of Health Sciences
P/Bag X680
Pretoria, 0001
Tshwane University of Technology
"Gauda Mahlatsi" <mahlatsigt@TUT.AC.ZA>

2

E-DRUG: Formulation of Ethambutol with other anti-TB drugs (2)
--------------------------------------------------------

Dear Gauda,

The literature says that Ethambutol HCl provides acidic environment and it
accelerates the chemical interaction between rifampicin and isoniazid
resulting in generation of related substance known and isonicotinyl
hydrazone. Thus normally the fixed dose combination of these 4 TB drugs are
difficult to stabilise.

Hope this will resolve your Qs.

Thanks,

Rakesh Chaurasia
Pharmacist-Regulatory Affairs
Macleods Pharmaceuticals Ltd.
Mumbai-India
"Rakesh Chaurasia" <rakeshchaurasia@macleodspharma.com>