Intrathecal injection of capsaicin can be used as a behavioural nociceptive test in mice.

Intrathecal injections in mice of substance P (SP), capsaicin and kainic acid elicited a behavioural response similar to that caused by noxious stimulation. Although the agents have different mechanisms of action, they showed a similar response, consisting of biting, scratching and licking the caudal parts of the body. Activation of adenosine receptors in the spinal cord with 5-N-ethylcarboxamide adenosine (NECA) had no effect on the response to substance P or to kainic acid, but reduced the response to capsaicin. It is concluded that different substances, injected intrathecally, can be used to differentiate between pre- and postsynaptic induced nociceptive behaviour, and that this assay may be valuable in assessing central antinociceptive effects of various drugs, especially those affecting systems modulated by substance P.

Noradrenaline depletion increases noradrenaline-induced antinociception in mice.

Mice were treated with N-2-chloroethyl-N-ethyl-2-bromobenzylamine hydrochloride (DSP4), which causes severe noradrenaline (NA) depletions in brain regions and the spinal cord, or vehicle i.p. They were tested 14 days later for antinociception induced by intrathecal injections of different doses of NA. A potentiation of the NA effect upon pain sensitivity was observed, with both an increase in the magnitude and duration of the antinociceptive responses. Upon biochemical analysis of spinal cords, it was found that DSP4-treated mice had a 80% depletion of NA, whereas dopamine and 5-hydroxytryptamine were unaffected. Radioligand binding of [3H]clonidine in membranes prepared from spinal cord, showed no differences in density of alpha 2-adrenoceptors, but the affinity had been increased, probably explaining the supersensitivity.

Efficacy of once-daily versus twice-daily administration of budesonide by Turbuhaler(R) in children with stable asthma.

We evaluated the efficacy of once-daily versus twice-daily treatment with budesonide, delivered by a Turbuhaler(R), in the management of children with stable asthma in a randomized, double-blind, parallel-group study involving 206 children (age 5-15 years). After a 2-week run-in period during which the children were maintained on their usual dose of budesonide (200 microg or 400 microg/day), patients were randomized to receive the same daily dose in either two daily administrations (morning and evening) or as a single dose in the morning over a period of 12 weeks. The primary efficacy variable was morning peak expiratory flow (PEF). The mean morning PEF during the run-in phase was 271 L/min in patients randomized to once-daily treatment and 264 L/min in those randomized to twice-daily treatment. The mean change from baseline to the last 2 weeks of the treatment period in the two groups was -0.3 L/min (95% confidence limits -6.6 to +6.0) and 2.5 L/min (-4.3 to +9.3). The estimated difference between the groups was -2.8 L/min, with 90% confidence limits of -10.4 + 4.5; these were close to the limits regarded as indicative of equivalence (-10 to +10), and hence the difference was not regarded as clinically relevant. Similarly, there were no significant differences between the groups in regard to secondary efficacy measures such as spirometric tests and symptom scores. Both treatments were well tolerated. We conclude that once-daily administration of budesonide by Turbuhaler(R) is as effective as twice-daily treatment in the management of stable asthma in children treated with inhaled steroids at doses of 200-400 microg/day.

(+)-8-OH-DPAT and 5-MeODMT induced analgesia is antagonised by noradrenaline depletion.

In experiments with both rats and mice the 5-HT agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and 5-methoxy-N,N-dimethyl-tryptamine (5-MeODMT) were shown to produce reliable analgesic effects after acute administration (1 mg/kg SC) in the tail-flick, hot-plate and shock-titration tests of nociception. Prior treatment with the noradrenaline neurotoxin, N-2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP4), systemically administered to both rats and mice abolished the analgesic effects of both the 5-HT agonist compounds in all the tests of nociception used. Intrathecal 6-hydroxydopamine (6-OHDA) treatment also abolished the analgesic effects of 8-OH-DPAT and 5-MeODMT; in the tail-flick test the analgesia induced by 8-OH-DPAT was reversed to an hyperalgesia. Biochemical analyses confirmed notable noradrenaline depletions in the spinal cord. It is concluded that an important interaction between presynaptic noradrenergic terminals and serotonergic receptor sites, possibly 5-HT1A, mediates spinal nociception processes.

Local anesthetics potentiate spinal morphine antinociception.

Some investigators have postulated a synergistic analgesic effect of local anesthetic agents and opiates when given intrathecally or epidurally, but little objective evidence has been presented to quantitate such an effect. A study was therefore undertaken to compare in mice the antinociceptive effects of intrathecal injections of mixtures of morphine with bupivacaine or lidocaine with the effects of these agents when administered alone. The antinociceptive effects (tail-flick and hotp-late tests) of morphine (0.1-1.6 micrograms) with either bupivacaine, 25 micrograms, or lidocaine, 200 micrograms, were significantly greater than the effects of morphine or the local anesthetics when administered alone. When morphine was administered with the local anesthetics, the intensity and the duration of antinociception were greater, although the time courses of the effects resembled that of morphine administered alone. An enhanced effect was also observed when combinations of local anesthetics and low doses of morphine were used that by themselves had no or little effect. The addition of morphine did not affect the motor block produced by the local anesthetics. The results indicate a potentiating effect of local anesthetics on spinal morphine antinociception, a finding that may have important clinical implications.

Complete blockade and attenuation of 5-hydroxytryptamine induced analgesia following NA depletion in rats and mice.

The effect of pretreatment with the noradrenaline neurotoxin, N-2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP4), upon the analgesia induced by various doses of 5-hydroxytryptamine (5-HT) was examined in rats and mice. DSP4 treatment (2 X 50 mg/kg, intraperitoneally) of rats caused a complete blockade of 5-HT induced analgesia in the tail-flick, hot-plate and shock titration tests. DSP4 treatment (1 X 50 mg/kg, intraperitoneally) of mice caused a partial blockade of 5-HT induced analgesia in the hot-plate test, but no significant blockade in the tail-flick test. These results are discussed with regard to serotonergic-noradrenergic interactions and the species discrepancy in nociceptive testing.

Efficacy of cumulative doses of salbutamol administered via Turbuhaler or Diskhaler in patients with reversible airway obstruction.

The study aimed to estimate the relative dose potency of salbutamol inhaled via Turbuhaler and Diskhaler. The 24 adult patients participating had chronic reversible airway obstruction. The study was of a double-blind, double-dummy, crossover, randomized design. Five doses of salbutamol Turbuhaler, 50, 50, 100, 200, and 400 microg, were given on one study day at intervals of 30 min. On another study day, five doses of salbutamol Diskhaler, 200, 200, 400, 800, and 1600 microg, were given with the same interval. The treatment days were separated by a washout period of at least 24 h. The inhalation technique was standardized and supervised. Efficacy variables were recorded before and after each study dose. The primary efficacy variable was forced expiratory volume in 1 s (FEV1). When parallel and linear cumulative dose-response curves were statistically compared on a logarithmic scale, the dose potency of salbutamol Turbuhaler vs salbutamol Diskhaler was 1.99 (95% confidence interval 1.52-2.54). This study indicates that only half the dose of salbutamol is required via Turbuhaler as via Diskhaler for the same bronchodilating effect.

Effects of formoterol and ipratropium bromide in COPD: a 3-month placebo-controlled study.

The aim of this study was to compare the effects of formoterol, ipratropium bromide and a placebo on walking distance, lung function, symptoms and quality of life (QoL) in chronic obstructive pulmonary disease (COPD) patients. A total of 183 patients (mean age 64 yrs, 86 female) with moderate-to-severe nonreversible COPD participated in this randomised, double-blind, parallel-group study. After a 2-week placebo run-in, patients were randomised to formoterol Turbuhaler 18 microg b.i.d. (delivered dose), ipratropium bromide 80 microg t.i.d. via a pressurised metered dose inhaler, or placebo for 12 weeks. Inhaled short-acting beta2-agonists were allowed as relief medication and inhaled glucocorticosteroids were allowed at a constant dose. The primary variable was walking distance in the shuttle walking test (SWT). Baseline mean SWT distance was 325 m, mean forced expiratory volume in one second (FEV1) was 40% predicted. Clinically significant improvements in SWT (>30 m) were seen in 41, 38 and 30% of formoterol, ipratropium and placebo patients, respectively (not significant). Mean increases from run-in were 19, 17 and 5 m in the formoterol, ipratropium and placebo groups, respectively. Both active treatments significantly improved FEV1, forced vital capacity, peak expiratory flow and daytime dyspnoea score compared with placebo. Formoterol reduced relief medication use compared with placebo. Neither active treatment improved QoL. Formoterol and ipratropium improved airway function and symptoms, without significant improvements in the shuttle walking test.