According to notice
published on its official website, FDA has approved a new drug named pretomanid tablet in combination
with bedaquiline and linezolid
for the treatment of extensively drugs
resistant tuberculosis of lungs. FDA principle deputy commissioner Amy Abernethy, M.D., Ph.D stated that threat
of antimicrobial-resistant infection is key challenge faced as a public health
agency. This new treatment is claimed to be highly Potent than any other
treatment options available till date
Key features of New Regimen
# This combination contains a new drug
Pretomanid which is combined with bedaquiline (Approved in 2012 as combination therapy for multidrug resistant bacterial TB/MDR-TB) and linezolid (already marketed drug for
treatment of multidrug resistant including streptococcus and methicillin
resistant staphylococcus aureus) in tablet form.
# This combination is for limited adult
patient with extensively drug resistant treatment intolerant or nonresponsive
multidrug resistant
# Before approval, clinical trial was
conducted in 109 patients with extensive drug resistant, treatment intolerance
and non-responsive multi drug resistant TB of lung. All the efficacy and safety
data were assessed and found to be satisfactory according to regulatory
requirements with typical success rate of 95 %. (whereas the previously
available treatment has only 34% in XDR and 55 % in MDR TB)
# Duration of treatment for this new
drug combination is total of 6 months, much shorter than the available one (18
-24 months).
# Adverse drugs reaction profile is
also considerable weighing risk-benefit ratio. Demonstrated reactions were
peripheral neuropathy, hyperamylasaemia, mild hepatic enzyme elevation,
hypoglycaemia, anaemia and general gastrointestinal upset.
Approval was taken from a special regulatory
guidance under FDA called ‘limited
population pathway for antibacterial and antifungal drugs’ by providing priority review and orphan drug designation which provides special incentives to encourage
the development of drugs for rare disease.
Why new drug is appreciable over existing one?
According
to WHO, in spite of availability of treatment and aggressive TB eradication
programmes worldwide, by the end of 2016, the estimated number of new cases of MDR TB was
4,90,000 from 123 WHO member states countries and the reliable data
suggested about 6.2% of those are XDR-TB. The real scenario might be more
intimidating than data suggested, because most of countries with
low-socioeconomic status do not have proper detection facility.
This new treatment will be more fortunate for the
countries like India which accounts for more than 9,000 XDR TB cases, second
highest after Russia throughout the world.
Long
duration of treatment and high side effect profile is One big reason of failure
of previously available treatment. Behind Mere success rate of bedaquiline
treatment, Patient withdrawal was the major reason. Practitioners stated, “retention of patient throughout
the duration is more challenging than anything else.”
Behind high
patient withdrawal rate, excessive side effect profile is major contributing
factors. As of now, the available evidences suggest that this new treatment is
going to fill this gap.
What actually XDR and MDR TB means?
When two
most powerful anti-TB drugs isoniazid and Rifampicin are resistant during
treatment, that is referred as MDR TB and along with these two drugs if
resistance to any of fluoroquinolone (ciprofloxacin, levofloxacin, moxifloxacin
etc.) and at least one of three injectable second line anti tubercular drugs
(amikacin, capreomycin and kanamycin), such condition is referred as
extensively drug resistance
(XDR-TB). Both MDR and XDR TB
takes longer duration of treatment than drug susceptive TB with low success
rate and high mortality.
Sources of
development of such TB is mainly because of improper treatment of susceptible
TB. Condition might have resulted from faulty prescription or improper regimen
of prescribed treatment. On other side people with MDR and XDR TB can transmit
the resistant disease pathogen.
Total of 19
XDR Tb cases were reported in Nepal in 2017; number is much higher for MDR. This
available new treatment may be an golden opportunity to “stop TB in Our lifetime”.
Thank You !!!
References:
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