Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tramadol, a centrally acting analgesic, consists of two enantiomers, both of which contribute to analgesic activity via different mechanisms. (+) Tramadol and the metabolite (+) -O- desmethyl-tramadol (M1) are agonists of the mu opioid receptor. (+) Tramadol also stimulates presinaptic release of serotonin and inhibits serotonin reuptake whereas (-) tramadol inhibits norepinephrine reuptake. Thus tramadol enhances inhibitory effects on pain transmission both by opioid and monoaminergic mechanisms. The complementary and synergistic actions of the two enantiomers improve the analgesic efficacy and tolerability profile of the racemate. Following oral administration the bioavailability of tramadol is high and with new slow release preparations twice daily administration enables effective pain control. The recommended maximum daily dose of tramadol is 400 mg/day. Tramadol is characterised by low plasma protein binding and quite extensive tissue distribution. Elimination is primarily by the hepatic route (metabolism by CYP2D6) and partly by the renal route. It is effective in different types of moderate-to-severe acute and chronic pain, including neuropathic pain, low back pain, osteoarthritis pain and breakthrough pain. It also causes fewer opioid-type adverse effects, e.g. nausea, drowsiness, vomiting, dry mouth and constipation. Although trials in literature demonstrate immune-stimulating effects of tramadol, there are also trials suggesting immunesuppressive effects that are lesser than morphine. Owing to its pharmacological properties, tramadol is more appropriate than NSAIDs for patients suffering from gastrointestinal and renal problems. Besides its proven clinical efficacy tramadol is a safe drug as respiratory depression, cardiovascular side effects, drug abuse and dependence are of minor clinical relevance, unlike some other opioids.
 ...
PMID:[An atypical opioid analgesic: tramadol]. 1678 63

Based on a medicinal-chemistry-guided approach, three novel series of druglike cycloalkyl-annelated pyrazoles were synthesized and display high affinity (pKi>8) for the sigma1 receptor. Structure-affinity relationships were established, and the different scaffolds were optimized with respect to sigma1 binding and selectivity versus the sigma2 receptor and the hERG channel, resulting in selective compounds that have Ki values (for sigma1) in the subnanomolar range. Selected compounds were screened for cytochrome P450 inhibition (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4), metabolic stability (rat and human liver microsomes), and cell-membrane permeability (Caco-2). They showed favorable in vitro ADME properties as well as favorable calculated druglike and experimental physicochemical properties. Furthermore, compounds 7 f and 17 a, for example, displayed high selectivity (affinity) for the sigma1 receptor against a wide range of other receptors (>60). With these valuable tool compounds in hand, we are further exploring the role of the sigma1 receptor in relevant animal models corresponding to such medicinal indications as drug abuse, pain, depression, anxiety, and psychosis.
 ...
PMID:A medicinal-chemistry-guided approach to selective and druglike sigma 1 ligands. 1689 45

Kava (Piper methysticum), used for relaxation and pain relief, has been one of the leading dietary supplements and several reports linking hepatic functional disturbances and liver failure to kava have resulted in a ban on sales in Europe and Canada and the issuance of warnings by the US FDA. The National Toxicology Program conducted 14-week rat studies to characterize the toxicology of kava exposure in Fischer 344 rats [National Toxicity Program. 90 day gavage toxicity studies of KAVA KAVA EXTRACT in Fischer rats and B6C3F1 mice. Research Triangle Park, NC; 2005a; National Toxicity Program. Testing status of agents at NTP (KAVA KAVA EXTRACT M990058). Research Triangle Park, NC; 2005b. (http://ntp.niehs.nih.gov/index.cfm?objectid=071516E-C6E1-7AAA-C90C751E23D14C1B)]. Groups of 10 male and 10 female rats were administered kava extract by gavage at 0, 0.125, 0.25, 0.5, 1.0, and 2.0 g/kg/day. Increased gamma-glutamyl-transpeptidase (GGT) activities were observed in the 2.0 g/kg males and 1.0 and 2.0 g/kg females, as well as increased serum cholesterol levels in males and females at 0.5 g/kg and higher. Increases in incidence and severity of hepatocellular hypertrophy (HP) were noted in males at 1.0 g/kg and females at 0.5 g/kg and higher, as well as increased liver weights. Immunohistochemical analyses of the expression of cytochrome-P450 (CYP) enzymes in liver of the control and 1.0- and 2.0-g/kg-treated groups indicated decreased expression of CYP2D1 (human CYP2D6 homolog) in 2.0 g/kg females and increased expression of CYP1A2, 2B1, and 3A1 in 1.0 and 2.0 g/kg groups of both sexes. The no observed adverse effect levels were decided as 0.25 g/kg in both genders, based on neurotoxic effects, increases in GGT, cholesterol, liver weight, and HP and decreases in body weight. Kava-induced hepatic functional changes in the F344 rat might be relevant to human clinical cases of hepatotoxicity following exposure.
 ...
PMID:Immunohistochemical analysis of expressions of hepatic cytochrome P450 in F344 rats following oral treatment with kava extract. 1705 82

Tramadol (Ultram, Ortho-McNeil Pharmaceutical, Inc., Raritan, NJ) is considered a Step 2 analgesic under the World Health Organization's guidelines for the treatment of patients with cancer pain. It is a centrally acting analgesic that has affinity for opioid receptors and influences the action of norepinephrine and serotonin at the synapse. This dual mechanism of analgesia makes it unique among Step 2 agents. It is metabolized by CYP2D6, which increases the potentialfor drug interactions. Unlike other opioids, it does not cause respiratory depression. Tramadol has been studied in cancer pain and neuropathic pain. It compares well with low-dose morphine as an analgesic. The purpose of this review is to critically examine the pharmacodynamics, pharmacology, drug interactions, and adverse effects of the drug, and, based on the data presented, discuss the drug's role in cancer care.
 ...
PMID:Tramadol: does it have a role in cancer pain management? 1731 16

We present a case of a 29 months old previously healthy child who experienced apnea resulting in brain injury following a dose of acetaminophen and codeine 2 days after an uneventful anesthetic for tonsillectomy. A genetic polymorphism leading to ultra-rapid metabolism of codeine into morphine resulted in narcosis and apnea. This paper discusses the use of codeine for pain relief, obstructive sleep apnea, the alteration of the CYP2D6 gene and the resulting effect on drug metabolism.
 ...
PMID:Apnea in a child after oral codeine: a genetic variant - an ultra-rapid metabolizer. 1861

Genomic variations influencing response to pharmacotherapy of pain are under investigation. Candidate genes such as (opioid)-receptors, transporters and other molecules important for pharmacotherapy are discussed. Drug metabolising enzymes represent a further major target of ongoing research in order to identify associations between an individual's genetic profile and drug response (pharmacogenetics). Polymorphisms of the cytochrome P450 enzymes influence analgesic efficacy of codeine, tramadol and tricyclic antidepressants (CYP2D6). Blood levels of some NSAIDs are dependent on CYP2C9 activity, whereas opioid-receptor polymorphisms are discussed for differences in opioid mediated analgesia and side effects. Pharmacogenetics as a diagnostic tool has the potential to improve patient therapy and care, and it is hoped that pharmacogenetics will individualise drug treatment to a greater extent in the near future.
 ...
PMID:The pharmacogenetics of analgesia. 1792 80

We describe the case of a patient with significant adverse effects from posttraumatic analgesic therapy with opioid analgesics who was found by microarray analysis to have a CYP2D6 genotype predictive of a poor metabolizer phenotype. In addition to her poor tolerance and limited response to opioid analgesics, she developed further discomfort when the antiemetic promethazine was administered to treat her gastrointestinal adverse effects. In our discussion we review the literature about the clinical impact of CYP450 2D6 polymorphisms in treatment with the commonly used opioid analgesics codeine, oxycodone, hydrocodone, hydromorphone, and morphine, as well as the antiemetic promethazine. The case we present, as well as the literature we review, demonstrates the clinical utility of CYP2D6 genotyping in patients with adverse effects from analgesia therapy.
Pain Pract 2007 Dec
PMID:Complicated pain management in a CYP450 2D6 poor metabolizer. 1850 81

The analgesic drug tramadol is bioactivated by CYP2D6 to the opioid receptor agonist O-desmethyltramadol. Case reports indicated that carriers of the CYP2D6 gene duplication may be at high risk for opioid adverse events. However, the effects of the CYP2D6 duplication on kinetics and dynamics of tramadol have not been systematically studied. Pharmacokinetics and effects were monitored after a single dose of 100 mg racemic tramadol in 11 carriers of a CYP2D6 gene duplication allele (ultrarapid metabolizer [UM]) and compared with 11 carriers of 2 active CYP2D6 genes (extensive metabolizer [EM]). Pharmacodynamics was measured by cold pressure test, pupillometry, and standardized adverse event recording. The maximum plasma concentrations of the active metabolite (+)R,R-O-desmethyltramadol were significantly higher in the UM group compared with the EM group (P = 0.005; t test) with a mean difference of 14 ng/mL (95% confidence limit of difference, 2-26 ng/mL). Median (+)R,R-tramadol area under the curve was 786 and 587 mug.h.L in EMs and UMs, and the corresponding median (+)R,R-O-desmethyltramadol area under the curve was 416 and 448 mug.h.L (P = 0.005, t test). There was an increased pain threshold and pain tolerance and a stronger miosis after tramadol in UMs compared with EMs. Almost 50% of the UM group experienced nausea compared with only 9% of the EM group. In conclusion, pharmacokinetic differences between EMs and UMs were smaller than expected; nevertheless, UMs were more sensitive to tramadol than EMs. Therefore, tramadol may frequently cause adverse effects in southern European and Northern African populations with a high proportion of UMs.
 ...
PMID:Effects of the CYP2D6 gene duplication on the pharmacokinetics and pharmacodynamics of tramadol. 1820 46

We report a case of life-threatening intoxication and a controlled re-exposure study to dextromethorphan. A 60-year-old man developed postsurgical neuropathic cervical pain treated by hydromorphone, gabapentin, clonazepam, and amitriptyline. He received a dextromethorphan preparation for a catarrhal syndrome. Two days later, he was admitted into an emergency department in a profound coma. Thirty-six hours later, after withdrawal of all drugs, the situation normalized. A genotyping for UDP-glucuronyltransferase 1A1 and CYP2D6 was followed by a re-exposure study. During the three days, vital parameters and side effects of drugs were prospectively recorded. The second day, dextromethorphan was introduced. No significant impairment in parameters nor influence on analgesic efficacy were noted. Dextromethorphan concentrations suggested an accumulation without reaching any steady state. Somnolence was noted for plasma concentrations around 100ng/mL. The CYP2D6*4 variant leading to a poor metabolizer phenotype was found. Moreover, this phenotype was potentially aggravated by amitriptyline intake. This study allowed the identification and the confirmation of the cause of the coma. In conclusion, it is probably wise to recommend avoiding dextromethorphan in patients taking tricyclic antidepressants or another inhibitor of CYP2D6. Drug-drug interactions are probably underdiagnosed and underreported, and drugs considered as safe may induce serious complications.
J Pain Symptom Manage 2008 Jul
PMID:Life-threatening dextromethorphan intoxication associated with interaction with amitriptyline in a poor CYP2D6 metabolizer: a single case re-exposure study. 1835 83

In this work we propose a mathematical model for the kinetics of tramadol, a synthetic opioid commonly used for treating moderate to severe pain. This novel theoretical framework could result in an objective criterion on how to adjust the assigned dose, depending on the genetic polymorphisms of CYP2D6. The model describes the coupled dynamics of tramadol and the metabolite O-desmethyltramadol. The effect of diffusion of the drug in the blood is here accounted for and we further hypothesize the existence of a time delay in the process of chemical translation from tramadol into metabolites. The system of coupled differential equations is solved numerically and the free parameters adjusted so to interpolate the experimental time series for the intravenous injection setting. Theoretical curves are shown to reproduce correctly the experimental profiles obtained from clinical trials. This enables in turn to extract an estimate of the metabolization rate. A difference in metabolization rate between CYP2D6 poor and extensive metabolizers is also found, and the stereoselectivity in the O-demethylation of tramadol highlighted. Our results allow one to quantify the dose of (+)-tramadol (resp. (-)-tramadol) administered to poor or extensive metabolizers, if the same effect is sought. The latter is here quantified through the blood concentration of (+)-metabolites (resp. (-)-metabolites).
 ...
PMID:Modelling the pharmacokinetics of tramadol: on the difference between CYP2D6 extensive and poor metabolizers. 1864 Jan 30


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>