A simple high-performance liquid chromatographic method was developed for the simultaneous determination of the therapeutic levels of acyclovir and ganciclovir in human plasma. After precipitation of plasma proteins with 6% perchloric acid, acyclovir and ganciclovir were simultaneously determined by reversed-phase chromatography with spectophotometric detection at 254 nm. The peak heights for acyclovir and ganciclovir were linearly related to their concentrations ranging from 0.063 to 2.080 micro g/mL. The recovery was 100.48-102.84% for acyclovir and 99.26-103.07% for ganciclovir. The intra- and inter-day relative standard deviation values were in the range 0.186-8.703% for acyclovir and 0.137-6.424% for ganciclovir. The detection limits for both compounds were 0.01 micro g/mL determined as the signal-to-noise ratio of 3. The present method is applicable to therapeutic monitoring during antiviral medication.

Two CER experiments were conducted with'licking'as the criterion response. In Experiment I, rats' (N=12) number of tongue laps in a drinking box was signiffcantly suppressed by the presentation of a CS which had been paired with electric shock previously. This suppression was not observed in the control group of 11 Ss. In Experiment II, the effect of US intensity upon CER was tested with 11 Ss using a within-subject design. The CS's of two modalities were reinforced with electric shock of two intensities in a balanced design. The Ss' drinking response was significantly more suppressed by the presentation of a CS which had been paired with stronger shock than of that with weaker shock. The results were discussed mainly from a methodological point of view.