Delta‐9‐tetrahydrocannabinol (THC), the main psychoactive cannabinoid in cannabis, may inhibit the cytochrome P450 enzyme CYP2C9. Consequently, cannabis use might infer a risk of drug‐drug interaction with substrates for this enzyme, which includes drugs known to have a narrow therapeutic window. In this study, we describe a case report of a 27‐year‐old man treated with warfarin due to mechanical heart valve replacement who presented with elevated international normalized ratio (INR) value (INR = 4.6) following recreational cannabis use. We conducted a review of the available literature, using the PubMed and EMBASE databases while following PRISMA guidelines. Following screening of 85 articles, three eligible articles were identified, including one in vitro study and two case reports. The in vitro study indicated that THC inhibits the CYP2C9‐mediated metabolism of warfarin. One case study reported of a man who on two occasions of increased marijuana use experienced INR values above 10 as well as bleeding. The other case study reported of a patient who initiated treatment with a liquid formulation of cannabidiol for the management of epilepsy, ultimately necessitating a 30% reduction in warfarin dose to maintain therapeutic INR values. The available, although sparse, data suggest that use of cannabinoids increases INR values in patients receiving warfarin. Until further data are available, we suggest patients receiving warfarin be warned against cannabis use.

In this systematic review, the current knowledge on all possible genetic factors that might influence the metabolism or clinical efficacy of tramadol has been collected and summarized. Only the effect of CYP2D6 polymorphisms on the metabolism of tramadol and the consequent effect on pain relief has been thoroughly studied and sufficiently established as clinically relevant.

Major depressive disorder is common among women in child-bearing age, and medical treatment is subject to substantial discussions and controversies. For Selective Serotonin reuptake inhibitors, SSRIs, a vast amount of data are available. For the newer antidepressant group of serotonin and noradrenaline reuptake inhibitors, SNRIs, significantly less data are available. Following the PRISMA guideline for systematic reviews, we performed a systematic search on the risk of major congenital malformations after first trimester in utero exposure to venlafaxine or duloxetine. We identified eight cohort studies reporting on the outcome upon in utero exposure to venlafaxine or duloxetine during the first trimester. The cumulated data for venlafaxine were 3186 exposed infants and 107 major malformations, resulting in a relative risk estimate and 95% confidence interval of 1.12 (0.92-1.35). The corresponding data for duloxetine were 668 infants and 16 major malformations, resulting in a relative risk estimate and 95% confidence interval of 0.80 (0.46-1.29). First-trimester in utero exposure to venlafaxine is not associated with an increased risk of major congenital malformations. The amount of data for duloxetine are significantly smaller but does not suggest a clinically important increased risk.Depression is common among women of child-bearing age. Approximately 20% of all women of child-bearing age will experience a depression during their life time, and 1% to 8% will use an antidepressant drug during pregnancy [1]. Untreated depression during pregnancy carries risk of severe consequences to the pregnant mother and her unborn child such as: epidural analgesia, caesarean section, intensive ward admission, preterm delivery, low birthweight, and disturbances in the child's neurocognitive and socio-emotional development [2]. Untreated depression during pregnancy increases the risk of post-partum depression 6-fold [3,4].The controversy of possible untoward foetal effects after in utero exposure to selective serotonin receptor inhibitors (SSRIs) has been ongoing for more than a decade. Data on more than 50,000 first-trimester SSRI-exposed newborn have accumulated, and it is accepted that first-trimester exposure to any antidepressant does not result in an overall increased risk of congenital malformations. The risk of cardiovascular malformations is still somewhat unclear, but if true, absolute risks are minor and may pertain to specific SSRIs, especially paroxetine and fluoxetine [5][6][7][8][9][10]. Comparatively, pregnancy data on the newer combined serotonin/noradrenaline receptor inhibitors (SNRI), venlafaxine and duloxetine, are scarce. A recent large Scandinavian study did not suggest an increased risk associated with venlafaxine [10], and a recent commentary concluded that the amount of information for duloxetine was too little [11].Current guidelines are vague and offer little decision support. The NICE guideline does not distinguish between the various types of antidepressants and offers no direct suggestio...

Intradermal injections of glutamate and capsaicin are attractive to use in human experimental pain models because hyperalgesia and allodynia mimic isolated aspects of clinical pain disorders. The aim of the present study was to investigate the reproducibility of these models. Twenty healthy male volunteers (mean age 24 years; range 18-38 years) received intradermal injections of glutamate and capsaicin in the volar forearm. Magnitudes of secondary pinprick hyperalgesia and brush-evoked allodynia were investigated using von Frey filaments (gauges 10, 15, 60 and 100 g) and brush strokes. Areas of secondary hyperalgesia and allodynia were quantified immediately after injection and after 15, 30 and 60 min. Two identical experiments separated by at least 7 days were performed. Reproducibility across and within volunteers (inter- and intra-individual variation, respectively) was assessed using intraclass correlation coefficient (ICC) and coefficient of variation (CV). Secondary pinprick hyperalgesia was observed as a marked increase in the visual analogue scale (VAS) response to von Frey gauges 60 and 100 g (P < 0.001) after glutamate injection. For capsaicin, secondary pinprick hyperalgesia was detected with all von Frey gauges (P < 0.001). Glutamate evoked reproducible VAS response to all von Frey gauges (ICC > 0.60) and brush strokes (ICC > 0.83). Capsaicin injection was reproducible for secondary hyperalgesia (ICC > 0.70) and allodynia (ICC > 0.71). Intra-individual variability was generally lower for the VAS response to von Frey and brush compared with areas of secondary hyperalgesia and allodynia. In conclusion, glutamate and capsaicin yield reproducible hyperalgesic and allodynic responses, and the present model is well suited for basic research, as well as for assessing the modulation of central phenomena.