Nova Microbiology Testing

In-Vitro Susceptibility of Antimalarial Drugs

Nova is an FDA, GLP Specialty Microbiology Laboratory serving the Drug Development Industry. Nova specializes in in-vitro susceptibility testing of antimalarial drugs.

At Nova our mission is to deliver value to our customers through Good Laboratory Practices (GLP), regulatory compliance and laboratory data management. We minimize risk for our customers and help them ensure the delivery of their products to market efficiently, cost effectively, and safely.

Minimal Inhibitory Concentration (MIC) - 3H Hypoxanthine Uptake (3HHU) Method

3H hypoxanthine uptake method is a standardized model (wherein 3H hypoxanthine is used (which is taken up by parasite for purine salvage and DNA synthesis) to determine the level of Plasmodium falciparum growth inhibition. Radiolabelled hypoxanthine uptake by the parasite is an indicator of its growth and multiplication. Parasites are cultured in the presence of different concentration of test compounds in media containing reduced concentration of hypoxanthine, after which 3H hypoxanthine is added for an additional incubation period before cell harvesting and measurement of radioactivity by a 1205 Betaplate reader. Mean counts per minute (cpm) are generally in the range of 20,000-60,000, with the acceptable minimum of 10,000.

Percent reductions are used to plot percentage inhibition of growth as a function of drug concentration. Inhibitory concentrations are determined by linear regression analyses on the linear segments of the dose response curve.

Minimal Inhibitory Concentration (MIC) - Giemsa Stained Slide (GSS) Method

Parasites are incubated with test compound and then parasitemia of control and treated groups are compared by counting Giemsa stained parasites by light microscopy. In this method, parasites are incubated in a 5% suspension of erythrocytes with an initial parasite density of 1-2% at 37°C. A sealed incubation chamber, continuously gassed with a mixture of 2% O2, 8% CO2, 90% N2 is used. Increase in the proportion of infected erythrocytes is assessed at the end of a 72 hour incubation period in control samples and at various concentrations of each drug. This method relies on a morphological criterion of response and reports a single concentration as the end point i.e. concentration of a drug in the first sample showing complete inhibition of growth. This measurement is known as the Minimum Inhibitory Concentration (MIC) method which is suitable for determining parasite susceptibility to a compound.

Nova's protocol for in-vitro susceptatility testing of antimalarial drugs uses criteria required by the United States Food and Drug Association for certain applications.

For more information or a quotation for testing contact Tamara Trow at 936-756-5333 x109 or ttrow@novatx.com