Shelf life is one of the important property of a drug for safety and quality. The shelf life of Picralima nitida (herbal drug) and three orthodox drugs (glibenclamide, ciprofloxacin, and pefloxacin) has been investigated. The stability study was done using UV spectrometry method. Their shelf life was determined by accelerated stability studies on the basis of first-order degradation kinetics and t10% (the time required to degrade 10% of a drug at 27°C). The stability was studied at temperatures of 45°C, 60°C and 70°C during the course of one month at one-week interval (1, 2, 3 and 4 weeks). The initial concentration of 5, 2.5, 25 and 100 mg/ml was used for Picralima nitida, glibenclamide, ciprofloxacin, and pefloxacin, respectively in the study. Influence of storage time and temperature on the drug samples were investigated. The half-life was also evaluated. All experiments were carried out in the year 2012. The concentrations of the drug samples were found to decrease with increase in storage time and temperature. The shelf life of ciprofloxacin, pefloxacin, and glibenclamide were found to be 535.18, 298.17 and 134.31 weeks, respectively. The half-life of ciprofloxacin, pefloxacin and glibenclamide were also found to be 3553.85, 1980 and 891.89 weeks, respectively. The shelf life and half-life of Picralima nitida could not be determined using UV spectrometry technique because of the presence of complex metabolites, which results in the irregular increase in absorbance and instability. Storage time and temperature was found to have a great influence on the concentration of the drug substances.