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    Pharmacological Reviews 04/1999; 51(1):83-133. · 22.35 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the rate of absorption and relative bioavailability of caffeine from a Stay Alert chewing gum and capsule formulation. This was a double blind, parallel, randomized, seven treatment study. The treatment groups were: 50, 100, and 200 mg gum, 50, 100, and 200 mg capsule, and a placebo. Subjects consisted of 84 (n=12 per group); healthy, non-smoking, males who had abstained from caffeine ingestion for at least 20 h prior to dosing and were randomly assigned to the treatment groups. Blood samples were collected pre-dose and at 5, 15, 25, 35, 45, 55, 65, 90 min and 2, 3, 4, 6, 8, 12, 16 and 29 h post administration. Plasma caffeine levels were analyzed by a validated UV-HPLC method. Mean Tmax for the gum groups ranged from 44.2 to 80.4 min as compared with 84.0-120.0 min for the capsule groups. The Tmax, for the pooled data was significantly lower (P<0.05) for the gum groups as compared with the capsule groups. Differences in Tmax were significant for the 200 mg capsule versus 200 mg gum (P<0.05). The mean ka values for the gum group ranged from 3.21 to 3.96 h-1 and for the capsule groups ranged from 1.29 to 2.36 h-1. Relative bioavailability of the gum formulation after the 50, 100 and 200 mg dose was 64, 74 and 77%, respectively. When normalized to the total drug released from the gum (85%), the relative bioavailability of the 50, 100 and 200 mg dose were 75, 87, and 90%, respectively. No statistical differences were found for Cmax and AUCinf for comparisons of the gum and capsule formulations at each dose. Within each dose level, there were no significant formulation related differences in Cmax. No significant differences were observed in the elimination of caffeine after the gum or capsule. The results suggest that the rate of drug absorption from the gum formulation was significantly faster and may indicate absorption via the buccal mucosa. In addition, for the 100 and 200 mg groups, the gum and capsule formulations provide near comparable amounts of caffeine to the systemic circulation. These findings suggest that there may be an earlier onset of pharmacological effects of caffeine delivered as the gum formulation, which is advantageous in situations where the rapid reversal of alertness and performance deficits resulting from sleep loss is desirable.
    International Journal of Pharmaceutics 04/2002; 234(1-2):159-67. · 3.99 Impact Factor
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    ABSTRACT: Guaraná is considered an ideal crop for supplementing the incomes of small peasant farmers in the Amazon basin. A fast-growing perennial, guaraná can be planted in the midst of manioc crops, allowing the formation of extensive orchards in the place of regenerating scrub once the manioc has been harvested. Traditional forms of guaraná agriculture practised by the Saterê-Mawé Indians compare favourably with the plantation system favoured by government agronomists. Indigenous techniques of hand-processing guaraná are also shown to produce better quality in the finished product than those practices adopted by industrial concerns. A detailed comparison of two systems of production show the Indians' implicit concern to avoid oxidization of the phenolic compounds in the seed, since this leads to the guaraná becoming dark in colour, bitter in taste, and irritating to the gastrointestinal tract. The short-term medicinal effects of guaraná are commonly thought to result from a high content of caffeine and associated alkaloids, as well as from considerable amounts of tannin. Future research may well show that various saponins also play an important part in the drug's pharmacology, particularly with regard to its long-term influence as a general tonic and prophylactic.
    Journal of Ethnopharmacology 12/1982; 6(3):311-38. · 2.94 Impact Factor

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