Atherosclerotic cardiovascular disease is a major problem despite the availability of drugs that influence major risk factors. New treatments are needed, and there is growing interest in therapies that may have multiple actions. Thyroid hormone modulates several cardiovascular risk factors and delays atherosclerosis progression in humans. However, use of thyroid hormone is limited by side effects, especially in the heart. To overcome this limitation, pharmacologically selective thyromimetics that mimic metabolic effects of thyroid hormone and bypass side effects are under development. In animal models, such thyromimetics have been shown to stimulate cholesterol elimination through LDL and HDL pathways and decrease body weight without eliciting side effects. We report here studies on a selective thyromimetic [KB2115; (3-[[3,5-dibromo-4-[4-hydroxy-3-(1-methylethyl)-phenoxy]-phenyl]-amino]-3-oxopropanoic acid)] in hu-mans. In moderately overweight and hypercholesterolemic subjects KB2115 was found to be safe and well tolerated and elicited up to a 40% lowering of total and LDL cholesterol after 14 days of treatment. Bile acid synthesis was stimulated without evidence of increased cholesterol production, indicating that KB2115 induced net cholesterol excretion. KB2115 did not provoke detectable effects on the heart, suggesting that the pharmacological selectivity observed in animal models translates to humans. Thus, selective thyromimetics deserve further study as agents to treat dyslipidemia and other risk factors for atherosclerosis.

In this 12-week trial, the thyroid hormone analogue eprotirome was associated with decreases in levels of atherogenic lipoproteins in patients receiving treatment with statins. (ClinicalTrials.gov number, NCT00593047.)

Involvement of the NMDA receptor system in the transmission of nociceptive information, including the development of central sensitization and a wind-up phenomenon, has increased interest in NMDA-receptor antagonists as antinociceptive drugs. This case report describes the use of an NMDA receptor antagonist 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) in a carefully selected patient with severe and intractable neurogenic pain in her left leg. The pain syndrome had components of a continuous deep pain, an allodynia, and a wind-up-like component, including afterdischarge and spread of painful sensations outside the territory of the injured nerve. After intrathecal (i.t.) administration of 200 nmol of CPP the continuous deep pain component and allodynia were unchanged, but the following 'wind-up' phenomenon with afterdischarge and spread of the pain sensation in the left half of the body was completely abolished. Another 500 nmol of CPP administered over 2 h did not improve pain relief. Pain thresholds for heat and cold stimulation, measured with a Marstock thermostimulator, did not change. There was no effect on blood pressure, heart rate, sensitivity, reflexes, coordination or motor performance. Psychotomimetic ketamine-like side effects developed 4 h after the last injection of CPP and were probably due to rostral spread of CPP. These early experiences with i.t. administration of NMDA-receptor antagonists to humans indicate that the NMDA-receptor system plays an important role in neurogenic pain and that antagonizing this system may be a useful way to obtain better pain control although psychotomimetic side effects due to rostral spread may be a problem.

Plasma concentrations, maximum regional brain concentrations, and specific regional binding in the brain after administration of 0, 0.1, and 0.2 mg/kg doses of (S)-ketamine were measured in a randomized, double-blind, crossover study in five volunteers and were related to induced effects such as analgesia, amnesia, and mood changes. Specific binding in the brain was assessed by simultaneous administration of (S)-[N-methyl-11C]ketamine quantified by positron emission tomography. High radioactivities in the brain corresponded to regional distribution of N-methyl-D-aspartate receptor complexes. A significant and dose-dependent reduction of binding was measured as a result of displacement of (S)-[N-methyl-11C]ketamine. Memory impairment and psychotomimetic effects were related to dose, plasma concentration 4 minutes after administration, and decreased regional binding of (S)-ketamine in the brain and were consistently seen at plasma and maximum regional brain (S)-ketamine concentrations higher than 70 and 500 ng/ml, respectively. The magnitude of specific binding of (S)-ketamine, measured with positron emission tomography, can be related directly to drug effects.

Statins effectively reduce levels of serum cholesterol and lower the risk of cardiovascular disease, but have limited effectiveness if stringent goals for serum low-density lipoprotein (LDL) cholesterol levels are not met or adverse effects develop, requiring a dose reduction or drug discontinuation. Previous studies have shown that thyroid hormone and some of its metabolites reduce levels of serum LDL cholesterol and have potentially favorable actions on other lipoproteins. The studies were discontinued because of reports of adverse effects on heart and bone, and possible deaths. In a recent report, eprotirome, a thyromimetic compound with minimal uptake in nonhepatic-tissues, was shown to reduce levels of serum total and LDL cholesterol and apolipoprotein B without apparent side effects in patients not receiving statin therapy.This randomized, placebo-controlled, double-blind, multicenter trial investigated the safety and efficacy of eprotirome in lowering the level of serum LDL cholesterol in patients with hypercholesterolemia who already were receiving simvastatin or atorvastatin. The aim of the study was to determine whether adding eprotirome to statin therapy would provide additional lipid-lowering actions without producing adverse extrahepatic thyromimetic effects. Patients were randomly assigned to receive daily oral doses of 25, 50, or 100 mcg of eprotirome or a placebo for 12 weeks. The primary study outcome was changes in serum LDL cholesterol. The potential adverse thyromimetic effects on the heart, bone, and pituitary were examined. Treatment of patients for 12 weeks already receiving statins with either placebo or eprotirome at a dose of 25, 50, or 100 g reduced the mean level of serum LDL cholesterol from 141 mg per deciliter (3.6 mmol per liter) at baseline to 127, 113, 99, and 94 mg per deciliter (3.3, 2.9, 2.6, and 2.4 mmol per liter), respectively; this represented a mean reduction from baseline of 7%, 22%, 28%, and 32%, respectively. Similar reductions were found in the secondary study outcomes, which included serum levels of apolipoprotein B, triglycerides, and Lp(a) lipoprotein. No evidence of adverse effects of eprotirome on the heart, bone, or pituitary was noted. Although reductions in serum levels of thyroxine occurred in some patients who received eprotirome, there were no changes in levels of thyrotropin or triiodothyronine.These findings demonstrate that the addition of eprotirome to statin therapy produces substantial further reductions in serum LDL cholesterol, non-high-density lipoprotein cholesterol, and apolipoprotein B. The drug appears to have an excellent safety profile.

Deep tissue pain can be related to reduced muscle blood flow, which comprises the metabolic demand under muscle work. The tissues and receptors involved in nociception after ischaemic muscle contractions are not known. The concentration of adenosine is increased after ischaemic contractions and might act as an algesic substance. In 15 subjects, adenosine, hypertonic saline (algesic), and isotonic mannitol (placebo) were infused into the tibialis anterior muscle and compared with the pain caused by ischaemic contractions. The muscle pain intensity (visual analogue scale; VAS), distribution, and quality were assessed. Pressure pain thresholds were recorded to assess the deep tissue sensitivity. Adenosine did not induce more pain than the placebo. The maximal VAS score after hypertonic saline and ischaemic contractions was higher compared with adenosine/placebo infusions. The duration and area of pain were significantly increased after hypertonic saline infusions compared with ischaemic contractions. Higher scores on the McGill pain questionnaire were given to the "stabbing", "burning", "heavy", and "exhausting" word categories after ischaemic contractions, and "cramping" was rated higher during hypertonic saline-induced muscle pain compared with ischaemic contractions. During hypertonic saline infusions, the pressure pain threshold was decreased compared with before and immediately after the pain had vanished. The present study shows that pharmacological levels of adenosine in skeletal muscle did not induce pain. Excitation of muscle nociceptors by hypertonic saline evoked hyperalgesia, larger areas of pain, and a different quality of pain compared with ischaemic contractions, suggesting that the pain after ischaemic contractions is mediated by other populations of nociceptors in muscle and/or other tissues than excited by hypertonic saline.

Understanding of the complex pharmacology of the spinal cord may lead to rational advances in pain treatment. It appears that a number of specific neurochemical mechanisms exist, by which spinally administered receptor selective agents may modify nociceptive transmission. Spinal administration of pure competitive N-methyl-D-aspartate (NMDA) antagonists affects only hyperpathic pain components, i.e. with signs of central sensitization, and most probably has a very limited role in postoperative pain treatment. On the other hand, it is well established that the non-competitive NMDA-antagonist ketamine gives good postoperative analgesia, probably by cerebral mechanisms also affecting other sensory modalities. Pure adenosine A1-receptor agonism at the spinal level mainly affects sensory allodynia to vibration, and is probably no alternative for postoperative pain treatment. In contrast, i.v. infusions of the non-selective A1/A2-receptor agonist adenosine given during a surgical procedure seem to decrease postoperative pain and requirements for postoperative analgesia. This apparent contradiction must be analysed further. Several drugs commonly used to treat postoperative pain, such as opioids, NSAIDs, ketamine and paracetamol, are linked to nitric oxide (NO) in their mechanism of action. The biosynthesis of NO in the central nervous system (CNS) is tonically involved in the nociceptive processing.

). Reductions in serum levels of LDL cholesterol, apolipoprotein B, triglycerides and lipoprotein(a) in hypercholesterolaemic patients treated with the liver-selective thyroid hormone receptor agonist eprotirome. J Intern Med 2015; 277: 331-342.Background. Liver-selective thyromimetic agents could provide a new approach for treating dyslipidaemia.