Search results for "Pharmacokinetic"
showing 10 items of 474 documents
Adverse drug reactions in the oral cavity
2012
Several drugs may have a number of adverse reactions (ADRs) involving the oro-facial region. The dose of the drug and the time required for the reaction to take place are relevant parameters; nonetheless, ADRs mechanisms are not always known and ADRs are not always predictable since aspects other than drug pharmacodynamics and/or pharmacokinetics, as well as various interacting variables contribute to the final outcome. All tissues and many functions of the oral cavity can be affected. In particular, salivary function is fre- quently involved and hypo-salivation is the main manifestation; several mucosal lesions with different morphology (ulcerations, vesiculo- bullous lesions, white lesion…
Biowaiver Monographs for Immediate Release Solid Oral Dosage Forms: Metformin Hydrochloride.
2021
Abstract Data are examined regarding possible waiver of in vivo bioequivalence testing (i.e. biowaiver) for approval of metformin hydrochloride (metformin) immediate-release solid oral dosage forms. Data include metformin's Biopharmaceutics Classification System (BCS) properties, including potential excipient interactions. Metformin is a prototypical transporter-mediated drug and is highly soluble, but only 50% of an orally administered dose is absorbed from the gut. Therefore, metformin is a BCS Class III substance. A BCS-based approval approach for major changes to marketed products and new generics is admissible if test and reference dosage forms have the identical active pharmaceutical …
Use of ICS/LABA (extra-fine and non-extra-fine) in elderly asthmatics.
2016
Age represents an exclusion criterion in randomized clinical trials designed to test the efficacy and safety of inhaled drugs in asthma. As a consequence, data on efficacy and safety of inhaled corticosteroid (ICS) and long-acting β2 agonist (LABA) combinations in elderly asthmatics are scanty. Older age is associated with an increased proportion of comorbid conditions; in addition, all organ functions undergo a process of senescence, thus reducing their ability to metabolize the agents. Overall, these age-associated conditions may variably, and often unpredictably, affect the metabolism and excretion of respiratory drugs. However, pharmacological treatment of asthma does not follow specifi…
The Biopharmaceutics Classification System: Subclasses for in vivo predictive dissolution (IPD) methodology and IVIVC
2013
The Biopharmaceutics Classification System (BCS) has found widespread utility in drug discovery, product development and drug product regulatory sciences. The classification scheme captures the two most significant factors influencing oral drug absorption; solubility and intestinal permeability and it has proven to be a very useful and a widely accepted starting point for drug product development and drug product regulation. The mechanistic base of the BCS approach has, no doubt, contributed to its wide spread acceptance and utility. Nevertheless, underneath the simplicity of BCS are many detailed complexities, both in vitro and in vivo which must be evaluated and investigated for any given…
Microseparation techniques for the study of the enantioselectivity of drug-plasma protein binding.
2009
Stereoselectivity in protein binding can have a significant effect on the pharmacokinetic and pharmacodynamic properties of chiral drugs. The investigation of enantioselectivity of drugs in their binding with human plasma proteins and the identification of the molecular mechanisms involved in the stereodiscrimination by the proteins represent a great challenge for clinical pharmacology. In this review, the separation techniques used for enantioselective protein binding experiments are described and compared. An overview of studies on enantiomer–protein interactions, enantiomer–enantiomer interactions as well as chiral drug–drug interactions, including allosteric effects, is presented. The c…
Induction of Drug Transporters Alters Disposition of Risperidone - A Study in Mice
2010
Pharmacokinetic interactions, e.g. modulation of drug transporters like P-glycoprotein at the blood-brain barrier, can be a reason for treatment non-response. This study focuses on the influence of induction of drug transporters on the disposition of the antipsychotic drugs risperidone and 9-hydroxyrisperidone. Brain and serum concentrations of risperidone and its active metabolite 9-hydroxyrisperidone, which are known P-glycoprotein substrates, were measured after drug transporter induction with rifampicin, dexamethasone or 5-pregnene-3beta-ol-20-on-16alpha-carbonitrile using high performance liquid chromatography. Disposition of risperidone and 9-hydroxyrisperidone was dramatically decrea…
Interactions and Monitoring of Antipsychotic Drugs
2012
As a consequence of individualized antipsychotic pharmacotherapy, many patients need more than a single drug, since they do not respond sufficiently to monotherapy. Other patients suffer from comorbid diseases and therefore require additional drugs from other pharmacological classes. Drug combinations, however, can give rise to pharmacokinetic and/or pharmacodynamic drug–drug interactions. Evaluation of pharmacokinetic interactions with antipsychotic drugs must consider substrate, inhibitor, and inducer properties for the cytochrome P450 (CYP) isoenzymes of all combined drugs. For consideration of pharmacodynamic interactions, special attention must be given to effects on dopamine D2, hista…
Pharmacokinetic rationale for switching from donepezil to galantamine.
2001
Galantamine, the most recently approved acetylcholinesterase inhibitor (AChEI) for use in the United States, has allosteric modulating activity at nicotinic receptors and inhibits acetylcholinesterase. This dual mechanism of action may make galantamine an attractive option for patients with Alzheimer's disease who have not benefited from their current therapy; thus, methods for switching patients from donepezil or rivastigmine to galantamine are needed. Protocols for switching patients from one AChEI to another must consider both the time required for washout of the first drug and the rate of dose escalation of the second drug. Both issues depend on the pharmacodynamics, pharmacokinetics, a…
Relevancia clínica de la selectividad de los inhibidores del cotransportador sodio-glucosa tipo 2
2016
Selectivity is the property of a drug to preferentially bind to a biological structure. Most drugs can bind and stimulate or inhibit more than one system. Therefore, it is important that they are selective for the intended site and that the doses used do not have effects on other sites, which could provoke adverse reactions. Selectivity is assessed through in vitro experiments on organs or isolated cells. If the aim is to compare drugs, the experiment should be conducted in the same tissue and with the same design. Even so, the results cannot be directly extrapolated to clinical practice due to the influence of pharmacokinetic properties, which allow an adequate dose of the drug to reach th…
Minimum effective dose for antidepressants - an obligatory requirement for antidepressant drug evaluation?
1996
Extensive clinical trials are required for registration and approval of new antidepressants in most countries including the requirement that a minimal effective dose should be determined. The rationale for this requirement is to avoid the use of unnecessarily high doses. The implication is that for every antidepressant, a dose exists that serves as a threshold, below which all doses are not effective or are clearly less effective in treating a major depressive episode. Dose titration and fixed dose studies are used to determine the minimal effective dose, but both strategies have limitations and often do not allow definite establishment of a clear-cut minimal effective dose. The effort of e…