Comparison of opioid rotation on pain, symptoms, and daily opioid dose in a supportive care clinic.

Background: Opioid rotation (OR) is used to decrease patients' cancer-related pain and mitigate opioid-induced adverse effects. There is limited evidence regarding its effect on symptoms and morphine equivalent daily dose (MEDD). The objective of this study was to investigate the effects of OR on pain scores, Edmonton Symptom Assessment Score (ESAS), and MEDD in patients with cancer.

Manipulating Pharmacodynamic Efficacy with Agonist + Antagonist Mixtures: In Vitro and In Vivo Studies with Opioids and Cannabinoids.

Pharmacodynamic efficacy of drugs to activate their receptors is a key determinant of drug effects, and intermediate-efficacy agonists are often useful clinically because they retain sufficient efficacy to produce therapeutically desirable effects while minimizing undesirable effects. Molecular mechanisms of efficacy are not well understood, so rational drug design to control efficacy is not yet possible; however, receptor theory predicts that fixed-proportion mixtures of an agonist and antagonist for a given receptor can be adjusted to precisely control net efficacy of the mixture in activating that receptor. Moreover, the agonist proportion required to produce different effects provides a quantitative scale for comparing efficacy requirements across those effects.

Effects of repeated treatment with monoamine-transporter-inhibitor antidepressants on pain-related depression of intracranial self-stimulation in rats.

Rationale: Synaptic neurotransmission with dopamine (DA), norepinephrine (NE), and serotonin (5-HT) is terminated primarily by reuptake into presynaptic terminals via the DA, NE, and 5-HT transporters (DAT/NET/SERT, respectively). Monoamine transporter inhibitors constitute one class of drugs used to treat both depression and pain, and therapeutic effects by these compounds often require repeated treatment for days or weeks.

Objectives: The present study compared antinociceptive effects produced by repeated treatment with monoamine transporter inhibitors in a preclinical assay of pain-related depression of positively reinforced operant responding.

Comparison of chemotherapy effects on mechanical sensitivity and food-maintained operant responding in male and female rats.

Chemotherapies of varying classes often cause neuropathy and debilitating chemotherapy-induced neuropathic pain sufficient to limit treatment and reduce quality of life for many patients battling cancer. There are currently no effective preventive or alleviative treatments for chemotherapy-induced neuropathic pain. Preclinical models have been developed to test candidate chemotherapy-induced neuropathic pain treatments; however, studies using these models rarely provide direct comparisons of effects of different chemotherapies or assess the degree to which chemotherapies produce clinically relevant signs of pain-depressed behavior.

Lack of paclitaxel effects on intracranial self-stimulation in male and female rats: comparison to mechanical sensitivity.

Paclitaxel is a cancer chemotherapy with adverse effects that include peripheral neuropathy, neuropathic pain, and depression of behavior and mood. In rodents, hypersensitive paw-withdrawal reflexes from mechanical stimuli serve as one common measure of paclitaxel-induced pain-related behavior. This study tested the hypothesis that paclitaxel would also depress rates of positively reinforced operant responding as a measure of pain-related behavioral depression.