Abstract
BackgroundCationic bilayers based on the inexpensive synthetic lipid dioctadecyldimethylammonium bromide (DODAB) have been useful as carriers for drug delivery, immunoadjuvants for vaccines and active antimicrobial agents.MethodsRifampicin (RIF) or isoniazid (ISO) interacted with DODAB bilayer fragments (BF) or large vesicles (LV). Dispersions were evaluated by dynamic light-scattering for zeta-average diameter (Dz) and zeta-potential (ζ) analysis; dialysis for determination of drug entrapment efficiency; plating and CFU counting for determination of cell viability of Mycobacterium smegmatis or tuberculosis, minimal bactericidal concentration (MBC) and synergism index for DODAB/drug combinations.ResultsDODAB alone killed micobacteria over a range of micromolar concentrations. RIF aggregates in water solution were solubilised by DODAB BF. RIF was incorporated in DODAB bilayers at high percentiles in contrast to the leaky behavior of ISO. Combination DODAB/RIF yielded MBCs of 2/2 and 4/0.007 μg/mL against Mycobacterium smegmatis or Mycobacterium tuberculosis, respectively. Synergism indexes equal to 0.5 or 1.0, indicated synergism against the former and independent action, against the latter species.ConclusionsIn vitro, DODAB acted effectively both as micobactericidal agent and carrier for rifampicin. The novel assemblies at reduced doses may become valuable against tuberculosis.
Highlights
Cationic bilayers based on the inexpensive synthetic lipid dioctadecyldimethylammonium bromide (DODAB) have been useful as carriers for drug delivery, immunoadjuvants for vaccines and active antimicrobial agents
Thereafter, aliquots of RIF solution, DODAB large vesicles (LV)/RIF or DODAB bilayer fragments (BF)/RIF before and after dialysis were added of ethanol (50%) in order to solubilize the DODAB bilayers
The insertion of RIF in the DODAB bilayer was supported by zetapotential decrease and could be understood from the favourable electrostatic attraction between the partially anionic RIF and the cationic bilayer which subsequently drove the hydrophobic effect
Summary
Cationic bilayers based on the inexpensive synthetic lipid dioctadecyldimethylammonium bromide (DODAB) have been useful as carriers for drug delivery, immunoadjuvants for vaccines and active antimicrobial agents. Tuberculosis (TB) is a curable infectious disease affecting mostly the lungs which is caused by Mycobacterium tuberculosis. Control of TB remains a serious challenge for public health due to the emergence of mutated strains presenting resistance to at least the two major anti-tuberculosis drugs, isoniazid and rifampicin [2]. Treatment of multidrug resistant TB requires prolonged and expensive chemotherapy using highly toxic, second-line drugs [2]. Resistance to these second line drugs develops and the disease becomes untreatable [2].
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