Use of CYP2D6 substrates and inhibitors during pain management with analgesic opioids: Drug-drug interactions that lead to lack of analgesic effectiveness.

BACKGROUND: Several opioids have pharmacogenetic and drug-drug interactions which may compromise their analgesic effectiveness, but are not routinely implemented into supportive pain management. We hypothesized that CYP2D6 phenotypes and concomitant use of CYP2D6 substrates or inhibitors would correlate with opioid analgesic outcomes. MATERIALS AND METHODS: An observational cross-sectional study was conducted with 263 adult chronic non cancer pain (CNCP) patients from a real-world pain unit under long-term CYP2D6-related opioid treatment (tramadol, hydromorphone, tapentadol or oxycodone). Metabolizer phenotype (ultrarapid [UM], normal [NM], intermediate [IM] or poor [PM]) was determined by the CYP2D6 genotype. The socio-demographic (sex, age, employment status), clinical (pain intensity and relief, neuropathic component, quality of life, disability, anxiety and depression), pharmacological (opioid doses and concomitant pharmacotherapy) and safety (adverse events) variables were recorded. RESULTS: The whole population (66 % female, 65 (14) years old, 70 % retired and 63 % attended for low back pain) were classified as PM (5 %), IM (32 %), NM (56 %) and UM (6 %). Multiple linear and logistic regressions showed higher pain intensity and neuropathic component at younger ages when using any CYP2D6 substrate (p = 0.022) or inhibitor (p = 0.030) drug, respectively, with poorer pain relief when CYP2D6 inhibitors (p=0.030) were present. CONCLUSION: The concomitant use of CYP2D6 substrates or inhibitors during opioid therapy for CNCP may result in lack of analgesic effectiveness. This aspect could be relevant for pharmacological decision making during CNCP management.

Farmacogenética y respuesta analgésica: hacia una medicina personalizada con análisis de las diferencias por sexo / Pharmacogenetics in analgesic response: towards a sex-differences personalized medicine

El dolor crónico supone una epidemia silenciosa que afecta a 1 de cada 5 personas adultas en Europa. Este hecho convive con el abuso que realizan algunos pacientes de los medicamentos analgésicos, circunstancia que está limitando su prescripción en el dolor crónico no oncológico. El reto sería poder seleccionar las personas que, a priori, tendrían una mejor respuesta analgésica en base a una serie de condicionamientos intrínsecos. La presente revisión analiza las diferencias en base al sexo y a la presencia de ciertas variantes en los genes que codifican el receptor opioide mu (OPRM1), la enzima metabolizadora del citocromo CYP2D6 y la catecol-O-metiltransferasa (COMT) que degrada catecolaminas. El objetivo es suministrar potenciales elementos explicativos que puedan orientar al profesional clínico en la selección de una analgesia más personalizada.(AU)

Chronic pain is a silent epidemic, affecting 1 in 5 adults in Europe. This fact coexists with the abuse of analgesic drugs by some patients, a circumstance that is limiting their prescription in chronic non-cancer pain. The challenge would be to be able to select the people who, a priori, would have a better analgesic response based on a series of intrinsic conditions. This review analyzes the differences based on sex and the presence of certain variants in the genes that encode the mu opioid receptor (OPRM1), the cytochrome metabolizing enzyme CYP2D6 and the catechol-O-methyltransferase (COMT) that degrades catecholamines. The objective is to provide potentially explanatory elements that can guide the clinical professional in the selection of a more personalized analgesia.(AU)

Sleep in autism: A biomolecular approach to aetiology and treatment.

People with autism spectrum disorder (ASD) commonly experience other comorbidities. Studies indicate that between 50% and 83% of individuals with ASD have sleep problems or disorders. The most commonly reported sleep problems are: (a) insomnia symptoms including the inability to get to sleep or stay asleep; and (b) circadian rhythm sleep-wake disorders, defined as a misalignment between the timing of endogenous circadian rhythms and the external environment. The circadian system provides timing information for the sleep-wake cycle that is regulated by the interaction of an endogenous processes (circadian - Process C, and homeostatic - Process S) and synchronizing agents (neurohormones and neurotransmitters), which produce somnogenic activity. A clinical priority in ASD is understanding the cause of these sleep problems in order to improve treatment outcomes. This review approaches sleep in autism from several perspectives: Sleep-wake mechanisms and problems, and brain areas and molecules controlling sleep (e.g., GABA and melatonin) and wake maintenance (e.g., serotonin, acetylcholine and glutamate). Specifically, this review examines how altered sleep structure could be related to neurobiological alterations or genetic mutations and the implications this may have for potential pharmacological treatments in individuals with ASD.

Human pharmacology of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) after repeated doses taken 2 h apart.

BACKGROUND: 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is one of the most abused recreational drugs. Its usual pattern of misuse includes repeated doses taken over a short time period that could influence MDMA pharmacology and toxicity. OBJECTIVE: This study aims to evaluate the pharmacokinetics and pharmacologically induced effects of two MDMA consecutive doses separated by 2 h. METHODS: A randomized, double-blind, crossover, and placebo-controlled trial included ten male volunteers participating in two experimental sessions. MDMA was administered as a single 100-mg dose or as a repeated dose (50 mg followed by 100 mg, administered at 2 h apart). Outcome variables included pharmacokinetics, physiological, subjective, and psychomotor effects. RESULTS: Following the repeated doses, plasma concentrations of MDMA were higher than those expected by simple dose accumulation (+16.2 % AUC; +12.8 % C (max)), but those of HMMA and HMA were significantly lower (-29.8 % AUC; -38.2 % C (max)). After the second dose, physiological effects, psychomotor performance, and subjective effects were lower than expected especially for euphoria and stimulation. MDMA-induced increases in diastolic and systolic arterial pressure and body temperature were in the range of those expected following MDMA concentrations. CONCLUSIONS: MDMA pharmacokinetics and metabolic disposition following two doses separated by 2 h show that the contribution of the first dose to the MDMA-induced mechanism-based metabolic inhibition was already apparent. The concentrations of MDMA after the second dose were slightly higher than expected. The effects on blood pressure and temperature after the second administration were slightly higher than those following the first, but for heart rate and subjective variables these were lower than expected considering the MDMA concentrations achieved, suggesting a possible tolerance phenomenon.

[Bioethics limitation of therapeutic effort in pediatrics]. / Limitación bioética del esfuerzo terapéutico en pediatría.

Given that the demand of society has shifted to seek maximum efficiency, maximum help based on the patient autonomy respect and awareness of its necessity, the limitation of therapeutic effort is one of the decisions more complex. Therefore, it should be an institutional objective to know the limitations of practice, assess and encourage improvement and in doubtful cases, resort to Assistive Bioethics Committees to advise on the development of clinical protocols in cases which the professional or the therapeutic team is faced with an ethical dilemma.

Ketanserin potentiates morphine-induced antinociception mediated by kappa-receptor activation.

How can we treat patients with reduced morphine doses without loosing the pain killing effect or morphine antinociceptive effects (MAE)? To address this question, we hypothesized that serotonin (5-HT2) receptor antagonism could enhance MAE mediated by kappa-opioid receptors. We pretreated mice with ketanserin, a 5-HT2 receptor antagonist, and measured the morphine dose required to observe analgesia. The morphine dose effective in 50% of animals (ED(50)) was reduced from 4.7 to 1.3mg/kg, and the morphine dose effective in 100% of animals (ED(max)) from 13.7 to 2.5mg/kg. Ketanserin has a similar enhancer effect when morphine, which has a dual role via mu and kappa receptors, was substituted by the antinociceptive spiradoline, a selective κ-opioid agonist. At a morphine dose of 3.5mg/kg, 30% of the mice showed antinociceptive behaviour, rising to 100% when ketanserin was co-administered and then reduced to 20% in the presence of nor-binaltorphimine, a kappa-opioid receptor antagonist. Our data strongly suggests a serotonergic inhibition of the kappa-opioid component of MAE and the possibility that this serotonergic inhibition could be reversed through 5-HT2 receptor antagonism.

The existence of a relationship between increased serum alanine aminotransferase levels detected in premarketing clinical trials and postmarketing published hepatotoxicity case reports.

BACKGROUND: Drug-induced liver injury (DILI) profile in most drugs' available information is based on both the incidence of alanine aminotansferase (ALT) elevations in clinical trials and published case reports. AIM: To assess the relationship between ALT elevations in clinical trials and the number of published case reports in the postmarketing setting. METHODS: Hepatotoxic drugs were identified from product labelling and classified in high-medium risk (Black Box Warning or Precautions section) or low risk (a statement in the Adverse Reactions section). Incidence of ALT elevations (> or = 3 x ULN) for drug (I(D)) and placebo (I(C)) treated patients in premarketing clinical trials and DILI published case reports were retrieved from product labelling and MEDLINE. RESULTS: The median I(C) was 10/1000. The high-medium-risk drugs' median I(D) was significantly higher compared with low-risk drugs (17/1000 vs. 10/1000; P = 0.046). Chi-squared test, absolute difference and odds ratio comparing I(D) and I(C) identified 35%, 51% and 77% of high-medium-risk drugs respectively. Less number of case reports were associated with low- than high-medium-risk drugs (1 vs. 7; P = 0.001). A high odds ratio in clinical trials (I(D) vs. I(C)) was the strongest predictor of published DILI case reports. CONCLUSION: A relationship between increased ALT incidence in premarketing clinical trials and postmarketing published case reports exists.

Pharmacogenetic relevance of the CYP2C9*3 allele in a tenoxicam bioequivalence study performed on Spaniards.

We performed a study to quantify CYP2C9 and CYP2C8 alleles influence on the variability observed in tenoxicam pharmacokinetic (PK) and implication in a bioequivalence study design performed on Spaniards. Eighteen healthy volunteers were included in an open, randomized, crossover, phase I bioequivalence study. Significant increases were found in CYP2C9*3 alleles vs. *1 and *2 in AUC(0-infinity) (median (min-max)): 256 (230-516) vs. 150 (100-268) and 169 (124-197) microg h/mL (p<0.01) and half-life time (t1/2) 102 (79-36) vs. 56 (45-94) and 64 (60-80)h (p<0.01). Non-significant differences were observed in C(max) 1.9 (1.8-2.9) vs. 2.4 (1.7-3.4), 2.5 (1.6-2.9) microg/mL or in according to CYP2C8 alleles presence. CYP2C9*3 allele is associated to a longer elimination time of tenoxicam. PK parameters calculated in bioequivalence studies (AUC(0-infinity), t1/2) may be influenced by the presence of CYP2C9*3 allele resulting in a high variability. Thus, bioequivalence studies of tenoxicam formulations should be designed considering genotype profile.

Efficacy and tolerance of metamizole versus morphine for acute pancreatitis pain.

BACKGROUND/AIMS: Morphine has been contraindicated for pain treatment in acute pancreatitis because of its presumed opioid-induced sphincter of Oddi dysfunction. However, scientific evidence supporting a deleterious influence on the clinical course is absent. This pilot study was undertaken to evaluate the efficacy and adverse events of metamizole versus morphine in acute pancreatitis. METHODS: 16 patients with acute pancreatitis were randomized to receive 10 mg/4 h s.c. (n = 8) morphine or 2 g/8 h i.v. (n = 8) metamizole. Pain scores were recorded every 4 h during 48 h after admission by a Visual Analogue Scale. Pethidine was additionally administered as a rescue therapy. RESULTS: 75% of patients achieved pain relief in the metamizole group versus 37.5% in the morphine group within 24 h of hospitalization (6/8 vs. 3/8; p: n.s.). The mean time to achieve pain relief was shorter in the metamizole group (10 +/- 6.6 vs. 17 +/- 18.3 h; p: n.s.). At the end of the study, 75% of patients achieved pain relief in the metamizole group versus 50% in the morphine group. Three patients in each group needed pethidine: 2 out of 3 achieved pain control in the metamizole group vs. 0 out of 3 in the morphine group. CONCLUSIONS: Intravenous metamizole shows a non-significant association with a quicker pain relief than morphine s.c. in acute pancreatitis. A larger randomized controlled trial should be desirable to confirm this result. and IAP.

Repeated doses administration of MDMA in humans: pharmacological effects and pharmacokinetics.

RATIONALE: 3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") is increasingly used by young people for its euphoric and empathic effects. MDMA presents non-linear pharmacokinetics, probably by inhibition of cytochrome P450 isoform 2D6. Users are known to often take more than one dose per session. This practice could have serious implications for the toxicity of MDMA. OBJECTIVE: To evaluate the pharmacological effects and pharmacokinetics of MDMA following the administration of two repeated doses of MDMA (24 h apart). METHODS: A randomised, double-blind, cross-over, placebo controlled trial was conducted in nine healthy male subjects. Variables included physiological, psychomotor performance, subjective effects, endocrine response and pharmacokinetics. MDMA 100 mg or placebo was administered in two successive doses separated by an interval of 24 h. RESULTS: MDMA produced the prototypical effects of the drug. Following a second dose, plasma concentrations of MDMA increased (AUC 77% and Cmax 29%) in comparison with the first. The increase is greater than those expected by simple accumulation and indicates metabolic inhibition. The pharmacological effects after the second dose were slightly higher than those observed after the first in the majority of variables including blood pressure, heart rate, most subjective effects and cortisol concentrations. The effects were similar in the case of pupil diameter, esophoria and prolactin. CONCLUSIONS: Pharmacological effects after the second administration were higher than those following the first but lower than expected. A disproportionate increase in plasma concentrations in MDMA and MDA was observed most likely due to metabolic inhibition. This inhibition lasts at least 24 h. Further experiments need to be conducted to evaluate its duration.