Acetaminophen, a common antipyretic-analgesic OTC drug is often administered orally anytime of the day with water or beverages irrespective of possible interactions. Zobo drink, is a sweetened water extract of the dried calyx of Hibiscus Sabdariffa. This work is designed to investigate the effect of zobo drink on an oral dose of acetaminophen. Six healthy male volunteers, ages 28.50 +/- 1.76 years, weighing 62.67 +/- 1.67kg participated in the study. The study was carried out in two phases. In the first phases an oral dose of acetaminophen (1g) was administered to the volunteers and in the second phases, zobo drink was ingested by the volunteers 1.30 h prior the administration of acetaminophen (1g). Acetaminophen concentration in plasma was determined using a validated spectrophotometric method. Pharmacokinetic values obtained were found to be in similar ranges as those previously reported. The absorption parameters t1/2a, Ka, Tmax, Cmax and AUC0-alpha showed no statistically significant changes (p>0.05) after the administration of zobo. There were however statistically significant changes (p<0.05) in Kbeta and t1/2beta of acetaminophen when administered after the zobo drink. This also resulted in 11.69% increase in ClT.

Analysis of quinine in plasma and whole blood samples dried on filter paper is described. Sample preparation involves liquid extraction of plasma and whole blood from the filter paper and subsequent solid-phase extraction using C8 Bond Elut cartridges. A reverse-phase liquid chromatography system with UV detection and fluorescence detection was used. The analytical characteristics of the method are reported, with a quantification limit of 0.1 microg mL(-1) and within an assay coefficient of variation of 5.6-8.4% in plasma and 6.5-12% in whole blood. Representative chromatograms are shown as a function of time for samples from human subjects after ingestion of a single 400-mg dose of quinine sulphate. Quinidine, dihydroquinine and metabolites are well separated from quinine with a resolution of above 1 (Rs>1).

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Acetaminophen is a common antipyretic-analgesic drug usually administered orally any time of the day. It was however claimed by Belanger et al, (1985) to have a longer elimination half-life (t1/2 beta) in rats when administered by 2100 h, than at 0700 h. This work is designed to investigate this claim in man and to study the circadian changes in acetaminophen pharmacokinetics at three dosing times; 0730 h, 1300 h and 2100 h. Seven healthy male volunteers, age 26.28 +/- 3.01 years, weighing 65.00 +/- 2.2 kg, were administered with 1000 mg oral acetaminophen at the three circadian time after a period of fast of not less than 4 h. The pharmacokinetic values obtained, though varied, are found to be in similar ranges with previously reported values. The absorption parameters ka and mean Tmax were significantly altered with dosing at 0730 h and 2100 h while the mean t1/2 alpha and ka were also significantly changed. There was a significant difference (P < 0.05) between the Tmax values obtained at 2100 h and that of 0730 h, while the 34.9% increase at dosing time 1300 h over 0730 h dosing times is not statistically significant (P > 0.05). Cmax was found to be 22.31 +/- 4.24 mcg/ml for 0730 h dosing time, while a decrease of 9.64 and 11.7% over this value was recorded for dosing time 1300 h and 2100 h respectively. The changes are however not statistically significant (P > 0.05). AUCo-a at 0730 h did not show any significant change when compared with values obtained at 1300 h and 2100 h, but there was a significant difference between the values obtained at 1300 h and 2100 h. Elimination half-life, t1/2 beta was found to be 1.68 +/- 0.67 h at 0730 h. There was an increase of 13.1% and 20.83% over this value at 1300 h and 2100 h. These increases were not statistically significant (p > 0.05). Although there are similar increases in t1/2 beta at the 1300 h and 2100 h dosing time as reported by Belanger et al 1985, the increases were not statistically significant in man.

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