Degradation in acidic conditions
OP was observed to be degraded to about 75% in acidic conditions, when treated with 0.1N HCL for 1 hr at room temperature (≈25ºC). The degradation rate constant and half life for OP in 0.1N HCL were 0.005149 % min-1 and 134.6 min,respectively. The drug was following linear and one-phase
degradation pattern in the case of 0.1N HCL. The degradation rate constant and half life for OP in 1.0N HCL were 0.03610 % min-1 and 19.20 min, respectively. The degradation pattern was ambiguous in the case of 1.0N HCL as drug had shown fast degradation at the initial time points (from 20 to 30 minute) followed by plateau phase as shown in the Figure 3a.