Comparison of pharmacokinetic and pharmacodynamic profiles of aspirin following oral gavage and diet dosing in rats
ABSTRACT Aspirin is one of the oldest drugs and has been purported to have multiple beneficial effects, including prevention of cardiovascular disease and cancer, in addition to its original indication for treatment of inflammation, fever and pain. In cancer chemoprevention studies using animal models, two methods of aspirin administration have been employed: oral gavage and diet. The untested assumption was that exposure and the resultant pharmacological effects are similar for these two administration methods when dosing is normalized on the basis of mg/kg body weight/day. This study examined and compared time-dependent plasma and colon mucosal concentrations of aspirin metabolite salicylate (aspirin concentrations were below level of quantification), plasma thromboxane B(2) concentrations, and colon mucosal prostaglandin E(2) concentration following these two different dosing paradigms in rats. Diet dosing yielded relatively constant plasma and colon salicylate concentration vs. time profiles. On the other hand, oral gavage dosing led to a rapid peak followed by a fast decline in salicylate concentration in both plasma and colon. Nevertheless, the exposure as measured by the area under plasma or colon concentration-time curve of salicylate was linearly related to dose irrespective of the dosing method. Linear relationships were also observed between colon and plasma salicylate areas under the curve and between colon prostaglandin E(2) and plasma thromboxane B(2) areas under the curve. Therefore, more easily accessible plasma salicylate and thromboxane B(2) concentrations were representative of the salicylate exposure and prostaglandin E(2) pharmacodynamic biomarker in the target colon, respectively.
- SourceAvailable from: Robert Chapin
[Show abstract] [Hide abstract]
- "concentration of salicylic acid after administration of a single gavage dose (embryo concentration was three times higher); assumes that 100% of teratogenic maternal aspirin dose is converted to salicylic acid, supported by pharmacokinetics in male rats at dose levels of aspirin that were teratogenic in pregnant rats Kimmel et al. (1971); Gupta et al. (2003); Kapetanovic et al. (2009) "
ABSTRACT: Validation of alternative assays requires comparison of the responses to toxicants in the alternative assay with in vivo responses. Chemicals have been classified as "positive" or "negative" in vivo, despite the fact that developmental toxicity is conditional on magnitude of exposure. We developed a list of positive and negative developmental exposures, with exposure defined by toxicokinetic data, specifically maternal plasma Cmax . We selected a series of 20 chemicals that caused developmental toxicity and for which there were appropriate toxicokinetic data. Where possible, we used the same chemical for both positive and negative exposures, the positive being the Cmax at a dose level that produced significant teratogenicity or embryolethality, the negative being the Cmax at a dose level not causing developmental toxicity. It was not possible to find toxicokinetic data at the no-effect level for all positive compounds, and the negative exposure list contains Cmax values for some compounds that do not have developmental toxicity up to the highest dose level tested. This exposure-based reference list represents a fundamentally different approach to the evaluation of alternative tests and is proposed as a step toward application of alternative tests in quantitative risk assessment. © 2014 Wiley Periodicals, Inc.Birth Defects Research Part B Developmental and Reproductive Toxicology 12/2014; 101(6). DOI:10.1002/bdrb.21132 · 1.17 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: This article reviews the major findings of research related to pharmacological pain therapies used in treating acute and chronic pain, it compares advantages and disadvantages of certain drugs used mainly in pain management (for example, opioids and non steroidal anti-inflammatory drugs), and others that have a secondary use in pain management (for example, skeletal muscle relaxants, antidepressants, and anticonvulsants) and their intended indications. Our goal is to present accurate up-to-date applicable data on these pharmacological choices.Neurosciences 07/2011; 16(3):203-12. · 0.39 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The role of platelets in hemostasis is well known, but few papers have reported their role in pain and edema induced by inflammatory agents. To evaluate the role of circulating platelets in the local injury induced by two diverse inflammatory agents, Bothrops jararaca venom (Bjv) and carrageenan. Rats were (i) rendered thrombocytopenic by administration of polyclonal anti-rat platelet IgG (ARPI) or busulfan, or (ii) treated with platelet inhibitors (aspirin or clopidogrel). Edema formation, local hemorrhage and the pain threshold were assessed after intraplantar injection of Bjv or carrageenan in rat hind paws. Additionally, whole platelets or platelet releasate were tested whether they directly induced hyperalgesia. Platelet counts were markedly diminished in rats administered with either ARPI (± 88%) or busulfan (± 96%). Previous treatment with ARPI or busulfan slightly reduced edema induced by Bjv or carrageenan. Injection of Bjv, but not of carrageenan, induced a statistically significance increase in hemorrhage in the hind paws of thrombocytopenic rats. Remarkably, hyperalgesia evoked by Bjv or carrageenan was completely blocked in animals treated with ARPI or busulfan, or pre-treated with aspirin or clopidogrel. On the other hand, intraplantar administration of whole platelets or platelet releasate evoked hyperalgesia, which was inhibited by pre-incubation with alkaline phosphatase. Thrombocytopenia or inhibition of platelet function drastically reduced hyperalgesia induced by injection of carrageenan or Bjv; moreover, platelets per se secrete phosphorylated compounds involved in pain mediation. Thus, blood platelets are crucial cells involved in the pain genesis, and their role therein has been underestimated.Journal of Thrombosis and Haemostasis 07/2011; 9(10):2057-66. DOI:10.1111/j.1538-7836.2011.04449.x · 5.55 Impact Factor