AN INVESTIGATION OF THE DOSE PROPORTIONALITY OF DEFLAZACORT PHARMACOKINETICS

The dose proportionality of deflazacort was assessed following single-dose oral administration at doses of 3, 6, and 36 mg to 24 healthy young adult volunteers. The active metabolite of deflazacort (21-desacetyl deflazacort) was monitored in plasma using a sensitive, semi-microbore liquid chromatographic method. C_max averaged 10·4±5·0, 19·8±7·5, and 132·6±52·5 ng mL⁻¹ for the 3, 6, and 36 mg doses, respectively. AUC(0–∞) averaged 38·5±37·1, 64·9±20·8, and 411·7±148·5 ng h mL⁻¹ for the same three doses, respectively. Elimination half-life ranged from 1·9±0·5 h at the 6 mg dose to 2·4±1·5 h at the 36 mg dose. Regression analyses of dose versus C_max and AUC(0–∞) yielded intercepts which were not significantly different from zero (p>0·05) and slopes which were significant (p<0·05). Regression analysis of dose versus apparent oral clearance yielded a slope which was not significantly different from zero (p>0·05). These data indicate that deflazacort exhibits dose-proportional pharmacokinetics.     

Early‐life adversity,epigenetics, and visceral hypersensitivity

Abdominal pain is associated with many gastrointestinal dysfunctions, such as irritable bowel syndrome (IBS), functional dyspepsia, and inflammatory bowel disease (IBD). Visceral hypersensitivity is a key reason for development of abdominal pain that presents in these gastrointestinal disorders/diseases. The pathogenesis of visceral hypersensitivity is complex and still far from being fully understood. In animal studies, visceral hypersensitivity has been linked to several early‐life adverse (ELA) events. In humans, IBD, functional dyspepsia, and IBS can have adult onset, though the adverse events that lead to visceral hypersensitivity are largely uncharacterized. In this issue of the journal, Aguirre et al. report the interesting finding that epigenetics underlies the effects of ELA events on visceral hypersensitivity. This mini‐review examines models of ELA events leading to visceral hypersensitivity and the potential role of epigenetics, as reported by Aguirre et al. and others.     

Mast cell corticotropin-releasing factor subtype 2 suppresses mast cell degranulation and limits the severity of anaphylaxis and stress-induced intestinal permeability

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Studies on the possible role of pharmacokinetics in the development of tolerance to morphine in the rat.

1. The possible role of pharmacokinetics of morphine in the development of tolerance to the analgesic and hyperthermic effects of morphine was studied in the rat. 2. Male Sprague-Dawley rats were made tolerant to morphine by implanting 6 morphine pellets each containing 75 mg of morphine base for 7 days. The assessment of the degree of tolerance to morphine and pharmacokinetic parameters were done 72 hr after pellet removal. 3. Tolerance developed to both the analgesic and hyperthermic effects of morphine as evidenced by decreased responses to morphine in morphine pellet implanted rats compared with placebo pellet implanted rats. 4. The pharmacokinetic parameters, AUC0-->infinity, Cmax, t1/2, k, MRT, Vss and Clt were determined after injecting 5 and 10 mg/kg doses of morphine intravenously to placebo and morphine pellet implanted rats and using a highly sensitive and specific RIA method to quantitate serum levels of morphine. For a 5 mg/kg dose of morphine, the AUC0-->infinity and t1/2 in morphine pellet implanted rats were significantly higher than in placebo pellet implanted rats, but the k value was lower. The other pharmacokinetic parameters for morphine in the two treatment groups did not differ. For 10 mg/kg dose, the only change was an increase in the MRT in morphine tolerant rats when compared to nontolerant rats. 5. The results establish that the development of tolerance to the analgesic and hyperthermic effects of morphine is not related to pharmacokinetics of morphine in serum but may be related to modification of receptor systems in the central nervous system.     

Multiple opiate receptors of brain and spinal cord in opiate addiction.

1. Chronic administration of opiates to rodents results in the development of tolerance to their pharmacological effects. Physical dependence also develops and is shown by the appearance of abstinence syndrome. 2. Opiates produce their effects by acting on three types of opiate receptors, namely mu, delta and kappa. The qualitative and quantitative aspects of the tolerance-dependence and abstinence symptoms observed after chronic administration of agonists acting at mu-, delta- and kappa-opiate receptors appear to differ. 3. Tolerance-dependence on mu-opiate agonists, such as morphine, is associated with down-regulation of mu-opiate receptors in spinal cord and specific areas of the brain but delta- and kappa-opiate receptors are unchanged. During abstinence from mu-opiate agonists, brain and spinal cord mu-, delta- and kappa-opiate receptors are unaffected. 4. Chronic administration of kappa-opiate agonists, such as U-50,488H, results in the development of tolerance to its pharmacological effects and a mild degree of physical dependence. Such changes are associated not only with alterations of delta and kappa opiate receptors in brain and spinal cord, but also primarily with a down-regulation of kappa-opiate receptors in spinal cord and specific brain regions. mu-Opiate receptors are unaffected. 5. Chronic administration of delta-opiate agonists results in down-regulation of brain delta-opiate receptors. 6. It is concluded that tolerance-dependence on mu-, delta- and kappa-opiate receptors is associated with down-regulation of their own type of receptors in the spinal and supraspinal areas. Abstinence, on the other hand, does not alter brain and spinal cord opiate receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of Panax ginseng on the development of tolerance to the pharmacological actions of morphine in the rat.

1. The effect of intraperitoneal administration of Panax ginseng on the development of tolerance to the analgesic and hyperthermic actions of morphine was determined in male Sprague-Dawley rats. Rats were rendered tolerant to morphine to different degrees by the subcutaneous implantation of either four pellets of morphine over a 3-day period or six pellets over a 7-day period. Each pellet contained 75 mg of morphine free base. Rats serving as controls were implanted with placebo pellets. 2. Daily administration of ginseng extract (6.25-50.0 mg/kg) for 3 days inhibited the development of tolerance to the analgesic effect but not to the hyperthermic effect of morphine in the four pellet schedule. 3. In six pellet schedule, daily administration of ginseng extract (25 and 50 mg/kg) for 7 days also inhibited the development of tolerance to the analgesic effect of morphine, but the 100 mg/kg dose had no effect. On the other hand, in six pellet schedule, the administration of ginseng extract (50 and 100 mg/kg) once daily for 7 days inhibited the development of tolerance to the hyperthermic effect of morphine. 4. It is concluded that in appropriate doses, ginseng extract has inhibitory activity on the development of tolerance to the pharmacological actions of morphine.