Feb. 17, 2010 Researchers at the Council for Scientific and Industrial Research (CSIR) are one step closer to providing tuberculosis (TB) sufferers with a once-a-week medicinal regime rather than their current daily doses.
A preclinical efficacy study demonstrated that TB drugs given once a week over a four-week period were just as effective as daily doses of the drug over the same period when the CSIR teams drug delivery technology is used.
The biggest problem with the current therapeutic regimen for TB is that the drugs should be taken once a day for a period of six to nine months in order to be effective. Also, according to the World Health Organization (WHO) Direct Observed Treatment shortcourse DOTs programme, the drugs need to be taken in the presence of a healthcare practitioner, says Dr Boitumelo Semete, senior researcher in the drug delivery programme at the CSIR.
Due to logistics, cost and other considerations, this is problematic for South African patients, especially in rural areas. As these drugs furthermore have a number of nasty side effects, many patients never complete their treatment course. This slims down their chances of recovery quite significantly, says Semete.
She explains that to improve patient compliance with TB treatment, the CSIR team is developing a way that will ensure that the antibiotic drugs are released and taken up in the affected cells over a longer period of time, using nanoparticles. This means that patients will only have to take the drugs once a week instead of daily and the associated side-effects will be less. It is also hoped that, due to more effective delivery and improved bioavailability of the drug, the total treatment period will be significantly reduced.
The preclinical efficacy study just completed is strong confirmation of the potential of the drug delivery technology. While there is still a long road ahead before we can take our technology to human clinical trials and eventually make the treatment available to patients, we have just reached a significant milestone along the way, she says.
The CSIR team, under leadership of Dr Hulda Swai, is developing a polymeric anti-TB nanodrug delivery system. Four different types of TB drugs are encapsulated in nano-sized polymeric particles. The drug will still be taken orally, but the particles will end up in systemic circulation in the body for a longer period instead of being eliminated by the body too quickly. This enables a sustained release into the body over longer periods with a gradual uptake of the antibiotics into the cells.
This methodology not only reduces the amount of drugs needed to effectively treat the disease, but also the associated side-effects and costs due to a lesser frequency of drugs taken.
To demonstrate the feasibility of this technology, the team encapsulated anti-TB drugs into polymeric nanoparticles of an average size on 250nm. An efficacy study was then conducted at the University of Cape Town. In this study, mice infected with TB were treated with the current anti-TB drug formulation once every day for four weeks as per standard regimen. A control group of TB-infected mice were treated with a once-a-week
dose of the nanoencapsulated anti-TB drugs over the same four-week
period. The encapsulated drugs resulted in the same reduction in bacterial burden as the conventional therapy.
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