Abstract: 
Chloroquine Phosphate (CP), indicated for the treatment of infections caused by some sensitive strains of malarial protozoa is not a drug candidate feasible to be administered via oral route in unconsciousness state and nausea with vomiting symptoms. Parenteral administration is associated with numerous toxic effects. This obviates an alternative dosage form. Rectal delivery of this drug is a good substitute to parenteral administration. Conventional dosage forms like suppositories can cause patient discomfort and may reach end of the colon; causing the drug to undergo first-pass effect. In the present work, Rectal Chloroquine– Poloxamer gel systems composed of Poloxamer and bioadhesive polymers such as Polyvinyl pyrrolidone K30, Carbopol 934P and Polycarbophil were developed and evaluated. The physicochemical properties such as physical appearance, clarity, gelation temperature, gel strength, rheological studies and mucoadhesive force of various formulations were investigated. The gelation temperature for the formulations varied between 32.4 – 36.5°C, the mucoadhesive force was found to be in the range of 37.34 – 321.05 dynes/cm² x 10² and rheological investigation revealed distinct shear thinning behaviour. Polycarbophil and Carbopol 934 P showed higher mucoadhesive strength, retardation in drug release from Pluronic F – 127 gels and significantly reduced the gelation temperature by about 6°C. The drug release was found to be matrix diffusion controlled and the release mechanism was found to be Fickian. These results prove that Pluronic F – 127 liquid suppositories containing either Carbopol 934 P or Polycarbophil are suitable alternative formulations to the conventional suppositories for being physically safe, convenient, and effective rectal dosage forms to deliver anti-malarial drugs.

Keywords: Rectal Drug Delivery, Malaria, Liquid Suppositories, Chloroquine Phosphate, Gelation Temperature, Mucoadhesive Force, Thermosensitive In Situ Gels.