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Renal (RIP) and hepatic (HIP) impairments are prevalent conditions in cancer patients. They can cause changes in gastric emptying time, albumin levels, hematocrit, glomerular filtration rate, hepatic functional volume, blood flow rates, and metabolic activity that can modify drug pharmacokinetics. Performing clinical studies in such populations has ethical and practical issues. Using predictive physiologically‐based pharmacokinetic (PBPK) models in the evaluation of the PK of alectinib, ruxolitinib, and panobinostat exposures in the presence of cancer, RIP, and HIP can help in using optimal doses with lower toxicity in these populations. Verified PBPK models were customized under scrutiny to account for the pathophysiological changes induced in these diseases. The PBPK model‐predicted plasma exposures in patients with different health conditions within average 2‐fold error. The PBPK model predicted an area under the curve ratio (AUCR) of 1, and 1.8, for ruxolitinib and panobinostat, respectively, in the presence of severe RIP. On the other hand, the severe HIP was associated with AUCR of 1.4, 2.9, and 1.8 for alectinib, ruxolitinib, and panobinostat, respectively, in agreement with the observed AUCR. Moreover, the PBPK model predicted that alectinib therapeutic cerebrospinal fluid levels are achieved in patients with non‐small cell lung cancer, moderate HIP, and severe HIP at 1‐, 1.5‐, and 1.8‐fold that of healthy subjects. The customized PBPK models showed promising ethical alternatives for simulating clinical studies in patients with cancer, RIP, and HIP. More work is needed to quantify other pathophysiological changes induced by simultaneous affliction by cancer and RIP or HIP.

Chronic pain is a persistent and debilitating health problem. Although the use of analgesics such as opioids is useful in mitigating pain, their prolonged use is associated with unwanted effects including abuse liability. This study assesses the antinociceptive effect of combining subtherapeutic doses of two opioids (morphine or tramadol) with the synthetic cannabinoid CP55940 (2-[(1R,2R,5R)-5-hydroxy-2-(3-hydroxypropyl)cyclohexyl]-5-(2-methyloctan -2-yl)phenol). It also evaluates the associated adverse effects of these drugs and combinations. Adult male rats were injected with intraplantar complete Freund’s adjuvant (CFA) to produce mechanical allodyia. Antinociceptive effect of morphine, tramadol, the synthetic cannabinoid CP55940, or their combinations was evaluated three to nine days post-CFA injections. Intracranial self-stimulation (ICSS) was utilized to evaluate the abuse liability of these drugs or their combinations. All drugs alone produced a dose-dependent antinociceptive effect. Morphine produced minimal effect on ICSS, but both tramadol and CP55940 produced dose-dependent depression of ICSS. Morphine at a dose of 0.32 mg/kg enhanced the antinociceptive effects of CP55940, in that, CP55940 produced antinociception at a lower dose (0.1 mg/kg) when compared to the vehicle. The aforementioned combinations did not change CP55940-induced depression of ICSS. On the other hand, tramadol failed to enhance the antinociceptive effect of CP55940. Our data suggest that combining CP55940 with morphine, but not tramadol, shows a better antinociceptive profile with no additional risk of abuse liability, which represents a potential pain management approach.

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Chronic pain is considered a growing healthcare problem becoming a major cause of global burden. Prolonged use of the currently used analgesics such opioids is associated with adverse effects; urging the need for safer alternatives. Cannabinoids are a group of compounds structurally related to Δ9‐tetrahydrocannabinol (Δ9‐THC). Both cannabinoids and opioids produce antinociception in different chronic pain animal models. However, therapeutic doses of these drugs may be accompanied by undesirable side effects, such as abuse liability and decrease locomotion in animals. The aim of this study was to assess the outcomes of combining range of doses of opioids and cannabinoids that are sufficient to produce antinociception without producing unwanted side effects. Inflammatory pain was induced by intra‐plantar injection of Complete Freund's Adjuvant (CFA) into the left hindpaw of adult male Sprague Dawley rats. Von Frey filaments were applied to the mid‐plantar aspect of the left hind paw using the “up‐down” method to determine the CFA‐induced mechanical allodynia. Antinociceptive effect of morphine (0.32, 1 and 3.2 mg/kg; i.p), the synthetic cannabinoid CP55940 (0.032, 0.1 and 0.32 mg/kg; s.c.), their combinations, or their vehicles was evaluated 3–9 day post‐CFA administration. Intracranial self‐stimulation (ICSS) test was utilized to evaluate the abuse liability of these drugs or their combinations. Morphine produced significant antinociceptive effects at 1 and 3.2 mg/kg, but not at the lowest dose of 0.32 mg/kg with minimal changes in ICSS. CP55940 showed significant antinociceptive effects only at the highest administered dose (0.32 mg/kg), while producing depression in ICSS at 0.1 and 0.32 mg/kg. The sub‐theraputic dose of morphine (0.32 mg/kg) was co‐administered with the different doses of CP55940 (0.032, 0.1 and 0.32 mg/kg). 0.32 mg/kg morphine enhanced the antinocicpetive effects of CP55940, such that CP55940 produced antinociception at lower dose (0.1 mg/kg) compared to vehicle. However, in ICSS test, the aforementioned combinations did not change CP55940‐induced depression of ICSS. In conclusion morphine and CP55940 produce analgesic effects at lower doses if combined together with no additional risk of abuse liability side effects, which may be useful in clinical practice.Support or Funding InformationScientific Research Support Fund (MPH/1/29/2016)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.