Background: Rifabutin (RFN) is bactericidal antibiotic with a very broad
spectrum of activity against gram positive & gram negative organisms including
Pseudomonas aeruginosa and specifically Mycobacterium tuberculosis. RFN inhibits
DNA dependent RNA polymerase activity in susceptible cells. In the instant
work, the therapeutic characteristics of RFN were intended for diagnostic rationale
by labeling it with 99mTc (Technetium-99m).
Objective: The 99mTc labeled RFN (99mTc-RFN) was investigated for labeling capacity,
steadiness in saline & serum, in vitro Mycobacterium tuberculosis (MBT) uptake
& distribution in MBT stained animal model rats.
Method: It was found that 99mTc-RFN prepared by mixing 2 mg of RFN, 2.5 mCi sodium
pertechnetate, 150 μg stannous chloride at pH 5.4 gave highest yield after 30
minutes and was intact above 90 % after 240 min at room temperature in saline.
Result: The 99mTc-RFN showed a stable profile in serum at 37 °C and impurities appeared
up 16 h was 15.20 %. The maximum in vitro MBT uptake observed in live
strain was 71.75 ± 0.75 %. The premier uptake observed in the MBT infected site
(target site) was 14.15 ± 0.00 %, in animal model rat.
Conclusion: Higher labeling capacity, steadiness in saline & serum, higher MBT uptake,
maximum uptake in the MBT infected sites and precise imaging posed 99mTc-
RFN as an alternate radio-drug for tuberculosis scintigraphy.