S-Ketamine oral thin film-Part 2: Population pharmacodynamics of S-ketamine, S-norketamine and S-hydroxynorketamine.

Ketamine is a versatile drug used for many indications and is administered via various routes. Here, we report on the pharmacodynamics of sublingual and buccal fast-dissolving oral-thin-films that contain 50 mg of S-ketamine in a population of healthy male and female volunteers. Twenty volunteers received one or two 50 mg S-ketamine oral thin films in a crossover design, placed for 10 min sublingually (n = 15) or buccally (n = 5). The following measurements were made for 6 h following the film placement: antinociception using three distinct pain assay; electrical, pressure, and heat pain, and drug high on an 11-point visual analog scale. Blood samples were obtained for the measurement of plasma S-ketamine, S-norketamine, and S-hydroxynorketamine concentrations. A population pharmacodynamic analysis was performed in NONMEM to construct a pharmacodynamic model of S-ketamine and its metabolites. P-values < 0.01 were considered significant. The sublingual and buccal 50 and 100 mg S-ketamine oral thin films were antinociceptive and produced drug high with effects lasting 2-6 h, although a clear dose-response relationship for antinociception could not be established. The effects were solely related to the parent compound with no contribution from S-norketamine or S-hydroxynorketamine. S-ketamine potency was lower for antinociception (C50 ranging from 1.2 to 1.7 nmol/mL) than for drug high (C50 0.3 nmol/ml). The onset/offset of effect as defined by the blood-effect-site equilibration half-life did not differ among endpoints and ranged from 0 to 5 min. In conclusion, the 50-mg S-ketamine oral thin film was safe and produced long-term antinociception in all three nociceptive assays with side effects inherent to the use of ketamine. The study was registered at the trial register of the Dutch Cochrane Center (www.trialregister.nl) under identifier NL9267 and the European Union Drug Regulating Authorities Clinical Trials (EudraCT) database under number 2020-005185-33.

S-Ketamine Oral Thin Film-Part 1: Population Pharmacokinetics of S-Ketamine, S-Norketamine and S-Hydroxynorketamine.

Ketamine is administered predominantly via the intravenous route for the various indications, including anesthesia, pain relief and treatment of depression. Here we report on the pharmacokinetics of sublingual and buccal fast-dissolving oral-thin-films that contain 50 mg of S-ketamine in a population of healthy male and female volunteers. Twenty volunteers received one or two oral thin films on separate occasions in a randomized crossover design. The oral thin films were placed sublingually (n = 15) or buccally (n = 5) and left to dissolve for 10 min in the mouth during which the subjects were not allowed to swallow. For 6 subsequent hours, pharmacokinetic blood samples were obtained after which 20 mg S-ketamine was infused intravenously and blood sampling continued for another 2-hours. A population pharmacokinetic analysis was performed in NONMEM pharmacokinetic model of S-ketamine and its metabolites S-norketamine and S-hydroxynorketamine; p < 0.01 were considered significant. S-ketamine bioavailability was 26 ± 1% (estimate ± standard error of the estimate) with a 20% lower bioavailability of the 100 mg oral thin film relative to the 50 mg film, although this difference did not reach the level of significance. Due to the large first pass-effect, 80% of S-ketamine was metabolized into S-norketamine leading to high plasma levels of S-norketamine following the oral thin film application with 56% of S-ketamine finally metabolized into S-hydroxynorketamine. No differences in pharmacokinetics were observed for the sublingual and buccal administration routes. The S-ketamine oral thin film is a safe and practical alternative to intravenous S-ketamine administration that results in relatively high plasma levels of S-ketamine and its two metabolites.

Reflectance infrared spectroscopy for in-line monitoring of nicotine during a coating process for an oral thin film.

A process analytical method using reflectance infrared spectrometry was developed for the in-line monitoring of the amount of the active pharmaceutical ingredient (API) nicotine during a coating process for an oral thin film (OTF). In-line measurements were made using a reflectance infrared (RI) sensor positioned after the last drying zone of the coating line. Real-time spectra from the coating process were used for modelling the nicotine content. Partial least squares (PLS1) calibration models with different data pre-treatments were generated. The calibration model with the most comparable standard error of calibration (SEC) and the standard error of cross validation (SECV) was selected for an external validation run on the production coating line with an independent laminate. Good correlations could be obtained between values estimated from the reflectance infrared data and the reference HPLC test method, respectively. With in-line measurements it was possible to allow real-time adjustments during the production process to keep product specifications within predefined limits hence avoiding loss of material and batch.

Acute experimental endotoxemia induces visceral hypersensitivity and altered pain evaluation in healthy humans.

Growing evidence suggests that systemic immune activation plays a role in the pathophysiology of pain in functional bowel disorders. By implementing a randomized crossover study with an injection of endotoxin or saline, we aimed to test the hypothesis that endotoxin-induced systemic inflammation increases visceral pain sensitivity in humans. Eleven healthy men (mean ± standard error of the mean age 26.6 ± 1.1 years) received an intravenous injection of either lipopolysaccharide (LPS; 0.4 ng/kg) or saline on 2 otherwise identical study days. Blood samples were collected 15 min before and 1, 2, 3, 4, and 6h after injection to characterize changes in immune parameters including proinflammatory cytokines. Rectal sensory and pain thresholds and subjective pain ratings were assessed with barostat rectal distensions 2h after injection. LPS administration induced an acute inflammatory response indicated by transient increases in tumor necrosis factor alpha, interleukin 6, and body temperature (all P<.001). The LPS-induced immune activation increased sensitivity to rectal distensions as reflected by significantly decreased visceral sensory and pain thresholds (both P<.05) compared to saline control. Visceral stimuli were rated as more unpleasant (P<.05) and inducing increased urge to defecate (P<.01). Pain thresholds correlated with interleukin 6 at +1h (r=0.60, P<.05) and +3h (r=0.67, P<.05) within the LPS condition. This report is novel in that it demonstrates that a transient systemic immune activation results in decreased visceral sensory and pain thresholds and altered subjective pain ratings. Our results support the relevance of inflammatory processes in the pathophysiology of visceral hyperalgesia and underscore the need for studies to further elucidate immune-to-brain communication pathways in gastrointestinal disorders.

Single-trial conditioning in a human taste-endotoxin paradigm induces conditioned odor aversion but not cytokine responses.

Immunological responses to bacterial endotoxin can be behaviorally conditioned in rodents. However, it is unclear whether an acute systemic inflammatory response can be behaviorally conditioned in humans. Thus, in a double-blind placebo-controlled study, 20 healthy, male subjects received either a single injection of lipopolysaccharide (LPS) or saline together with a novel tasting beverage (conditioned stimulus, CS). Five days later, all subjects received a saline injection and were re-exposed to the CS. Blood was drawn prior to as well as 0.5, 1.5, 3, 4, 6, and 24 h after LPS administration or CS re-exposure. Endotoxin administration led to transient increases in plasma concentrations of interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α and to a significant rise in body temperature. Sole presentation of the CS during evocation did induce neither alterations in body temperature nor changes in plasma cytokine levels. However, subjects in the experimental group rated the smell of the CS significantly more aversive compared to the control group. Employing endotoxin as a US in a single trial taste-immune conditioning paradigm in humans shows a behaviorally conditioned smell aversion but no learned alterations in cytokine levels.

Dose-dependent effects of endotoxin on neurobehavioral functions in humans.

Clinical and experimental evidence document that inflammation and increased peripheral cytokine levels are associated with depression-like symptoms and neuropsychological disturbances in humans. However, it remains unclear whether and to what extent cognitive functions like memory and attention are affected by and related to the dose of the inflammatory stimulus. Thus, in a cross-over, double-blind, experimental approach, healthy male volunteers were administered with either placebo or bacterial lipopolysaccharide (LPS) at doses of 0.4 (n = 18) or 0.8 ng/kg of body weight (n = 16). Pro- and anti-inflammatory cytokines, norephinephrine and cortisol concentrations were analyzed before and 1, 1.75, 3, 4, 6, and 24 h after injection. In addition, changes in mood and anxiety levels were determined together with working memory (n-back task) and long term memory performance (recall of emotional and neutral pictures of the International Affective Picture System). Endotoxin administration caused a profound transient physiological response with dose-related elevations in body temperature and heart rate, increases in plasma interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α and IL-1 receptor antagonist (IL-1ra), salivary and plasma cortisol, and plasma norepinephrine. These changes were accompanied by dose-related decreased mood and increased anxiety levels. LPS administration did not affect accuracy in working memory performance but improved reaction time in the high-dose LPS condition compared to the control conditon. In contrast, long-term memory performance was impaired selectively for emotional stimuli after administration of the lower but not of the higher dose of LPS. These data suggest the existence of at least two counter-acting mechanisms, one promoting and one inhibiting cognitive performance during acute systemic inflammation.

Dehydroepiandrosterone modulates survival and immune functions during sepsis depending on the way of drug administration.

BACKGROUND: Administration of dehydroepiandrosterone (DHEA) has been demonstrated to improve survival and cellular immune functions during systemic inflammation. Although there is evidence that the route of drug application may profoundly affect the DHEA-induced effects the impact of this parameter remains to be established. MATERIALS AND METHODS: Male NMRI mice were subjected to sham-operation (laparotomy) or sepsis (cecal ligation and puncture). Animals received saline or DHEA (20 mg/kg/day) given either subcutaneously, intravenously, or intraperitoneally. Termination of animals was performed 48 hrs after induction of sepsis in order to monitor splenocyte proliferation ((3)H-thymidine incorporation assay), splenocyte apoptosis (Annexin V binding capacity), and cytokine release (IL-1ß and IL-6, ELISA). RESULTS: Subcutaneous DHEA administration improved the survival rate of septic mice 48 hrs after induction of CLP (75% vs. 47%). This effect was paralleled by a restoration of splenocyte proliferation, a decreased cellular apoptosis rate of splenocytes, and an attenuation of pro-inflammatory cytokine release. In contrast, no significant effects on the survival rate or cellular immune functions were observed following intravenous or intraperitoneal DHEA administration. CONCLUSIONS: Subcutaneous administration of DHEA induced an increased survival rate and improved cellular immune functions in septic mice. In contrast, no comparable effects were noticed following intravenous or intraperitoneal administration of DHEA.

Dehydroepiandrosterone during sepsis: does the timing of administration influence the effectiveness.

BACKGROUND: Administration of dehydroepiandrosterone (DHEA) has been demonstrated to improve survival and cellular immune functions during systemic inflammation. Although there is evidence that the time point of drug application may profoundly affect the DHEA-induced effects the impact of this parameter remains to be established. METHODS: Male NMRI mice were subjected to sham-operation (laparotomy) or sepsis (cecal ligation and puncture). Animals received saline or DHEA (20 mg/kg/d) given subcutaneously either 1 h before or 8 h after induction of CLP. Termination of animals was performed 48 h after induction of sepsis in order to monitor splenocyte proliferation ((3)H-thymidine incorporation assay), splenocyte apoptosis (annexin V binding capacity), and cytokine release (IL-1ß and IL-6, enzyme-linked immunoassay (ELISA). RESULTS: DHEA administration improved the survival rate of septic mice 48 h after induction of CLP independent of the time point of application (44% versus 75% pretreatment groups; 47% versus 78% treatment groups). This effect was paralleled by a restoration of splenocyte proliferation, a decreased cellular apoptosis rate of splenocytes, and a modulation of pro-inflammatory cytokine release. CONCLUSIONS: Administration of DHEA either given before or after the development of clinical apparent septic symptoms reliably improves survival and cellular immune functions in a murine model of sepsis.