Cumulative Dose-response Study Research Articles

Sertraline effects on cerebrospinal fluid monoamines and species-typical socioemotional behavior of female cynomolgus monkeys

Although widely prescribed, little is known about the effects of selective serotonin reuptake inhibitors (SSRIs) on social behavior and cerebrospinal fluid (CSF) monoamines in female primates. The objective of this study was to determine the effects of sertraline on agonistic and affiliative behavior. Twenty-one adult female cynomolgus monkeys were housed in small, stable social groups, trained to participate in oral dosing, and began a 5-week cumulative dose-response study. Serial doses of 0, 5, 10, 15, and 20 mg/kg of sertraline were administered orally for 1 week each. Behavior was recorded daily during 10-min observations before and 4 h after dosing. On the seventh day of dosing, circulating sertraline/desmethylsertraline and CSF monoamines/metabolites were determined 4 h after the last dose. At 20 mg/kg, circulating sertraline/desmethylsertraline was in the therapeutic range. CSF 5-hydroxyindole acetic acid decreased by 33 % (p < 0.05). Overall aggression, submission, locomotion, and time alone decreased, whereas affiliative behaviors (body contact, grooming) increased (all p values <0.05). Effects of sertraline on aggression and submission were social status-dependent, reducing aggression in dominants and submission in subordinates. A clinically relevant oral dose of sertraline resulted in CSF metabolite changes similar to those observed in patients and altered the socioemotional behavior of female monkeys. Changes in CSF 5-HT and dopamine are novel observations that may be sex-specific. The robust effects of sertraline on aggression and affiliation may explain the efficacy of SSRIs on a range of human behavioral pathologies that share the characteristics of increased aggression and decreased sociality.

Bronchodilatory effects of NVA237, a once daily long-acting muscarinic antagonist, in COPD patients

NVA237 is a novel, once daily inhaled long-acting muscarinic antagonist administered via a dry powder inhaler. This study aimed to assess the 24-h bronchodilatory effect following 14 days of treatment with inhaled NVA237 in patients with mild, moderate or severe COPD. This was a randomized, double-blind, placebo-controlled, two-period, crossover, multicenter study. A total of 33 patients (≥ 40 years; smoking history of ≥ 10 pack-years) were randomized to receive NVA237 50 μg once daily followed by placebo or placebo followed by NVA237 50 μg for 14 days. Treatment periods were separated by a 7-14 day washout period. The primary variable was the mean forced expiratory volume in 1 s (FEV(1)) derived from the area under the curve (AUC) between 0 and 24 h post-dose on Day 14. The 24-h FEV(1) profiles showed a consistent bronchodilator effect for NVA237 versus placebo on Day 14. Least square (LS) mean difference in FEV(1) AUC(0-24 h) values between NVA237 and placebo was 163 mL (P < 0.001). There were significant increases in mean FEV(1) AUC(0-12 h) (LS mean difference 165 mL, P = 0.001) and FEV(1) AUC(12-24 h) (161 mL, P < 0.001) versus placebo. NVA237 significantly improved peak FEV(1) (by 208 mL, P < 0.001) and trough FEV(1) (by 154 mL, P = 0.003) versus placebo on Day 14. NVA237 was well tolerated; all adverse events were mild or moderate in intensity and not related to study drug. NVA237 50 μg once daily was well tolerated and showed significant and sustained 24-h bronchodilation in patients with COPD.

Sustained 24-h efficacy of NVA237, a once-daily long-acting muscarinic antagonist, in COPD patients

NVA237 is a once-daily inhaled long-acting muscarinic antagonist in development for the treatment of COPD. This randomized, double-blind, placebo-controlled, four-period, incomplete block crossover study, with open-label active comparator (tiotropium), assessed the efficacy and safety of NVA237. Patients (>or=40 years; smoking history >or=10 pack-years) with stable moderate-to-severe COPD (post-bronchodilator FEV(1) >or= 30% and <80% predicted, FEV(1)/FVC < 0.7) received NVA237 12.5, 25, 50 or 100 microg, placebo, or tiotropium 18 microg once-daily for 7 days. The primary endpoint was mean trough (23-24 h post-dose) FEV(1) on Day 7. Secondary endpoints included mean trough FEV(1) on Day 1, and FEV(1) and FVC at individual time points post-dose on Days 1 and 7. 83 patients (mean age 64.4 years; male 83.1%; mean COPD duration 6.7 years; mean post-bronchodilator FEV(1) 1.5 L/52.7% predicted) were randomized; 78 completed. Mean trough FEV(1) on Day 7 and Day 1 was significantly higher with all active treatments versus placebo (p < 0.05). NVA237 50 microg, 100 microg and tiotropium showed clinically relevant improvements versus placebo on Day 7 (differences of 131, 142 and 127 mL, respectively; p < 0.0001) and 1 (differences of 121, 135 and 112 mL, respectively; p < 0.0001). On Day 1, but not Day 7, FEV(1) was significantly higher (p < 0.05) with NVA237 50 and 100 microg versus tiotropium from 5 min up to 2 and 4 h post-dose, respectively. All doses of NVA237 and tiotropium were well tolerated. NVA237 once-daily was effective and well tolerated versus placebo, and demonstrated rapid and sustained 24-h bronchodilation. (ClinicalTrials.gov Identifier: NCT00501852).

Effect of extracellular calcium on the additive effect of theophylline on the cardiac response to catecholamine

At diff erent extracellular calcium concentrations, the positive inotropic eff ect of isoproterenol and isoproterenol in combination with theophylline, a phosphodiesterase inhibitor have been evaluated in the isolated frog heart and the isolated guinea pig left atria to investigate whether extracellular calcium produces any eff ect on the additive eff ect of the theophylline on the cardiac response to catecholamine. Cumulative dose response study of isoproterenol and isoproterenol in presence of theophylline at diff erent extracellular calcium concentration was performed. Th e study revealed an increase in additive eff ect of theophylline on the cardiac response to catecholamine with increase in extracellular calcium concentration, but increase in extracellular calcium concentration decreased the myocardial responsiveness to additive eff ect of theophylline and isoproterenol combination. Th e mechanism of positive inotropic eff ect of isoproterenol and in combination with theophylline involves increase in intracellular CAMP by diff erent pathways and extracellular calcium produces positive inotropic eff ect by initiating the interaction between the contractile proteins actin and myosin.The study revealed that an increase in the concentration of extracellular calcium increased the additive eff ect of theophylline and isoproterenol combination, but a decrease in the myocardial responsiveness was observed. Key words: Additive eff ect, cAMP, isoproterenol, positive inotropic eff ect, theophylline and calcium

Effects of 5-hydroxytryptamine on Rocuronium-induced Neuromuscular Blockade in a Rat Phrenic Nerve-hemidiaphragm Preparation

Background: The 5-hydroxytryptamine 3 receptor (5-HT3R) is a member of a superfamily of ligand-gated ion channels which has structural similarities and common evolutionary origin to those of the nicotinic acetylcholine receptor (nAChR). 5-hydroxytryptamine (5-HT) and muscle relaxants may have cross reaction. Rocuronium is a non-depolarizing neuromuscular blocking agent which has a rapid onset. The aim of this study was to examined the effects of 5-HT on rocuronium-induced neuromuscular blockade in a rat phrenic nerve-hemidiaphragm preparation. Methods: Institutional approval was obtained for the experimental procedure. Fifty male Sprague-Dawley rats (150－200 g) were divided into 5 groups; the control, and 0.1, 1, 10, and 20μg/ml of 5-HT. The animals were injected with phentobarbital at 40 mg/kg into the peritoneal cavity. The hemidiaphragm with the phrenic nerve was dissected and then mounted in a bath containing 100 ml Krebs solution at room temperature. The phrenic nerve was stimulated at the supramaximal intensity using a Grass® S88 stimulator via an SIU5 isolation unit. The twitch height was measured and recorded using a precalibrated Grass® FT88 force displacement transducer and recorded with a Grass® 79 polygraph, respectively. In the cumulative dose-response study, the rocuronium 100μg/dl and each dose of 5-HT were administered simultaneously administered, with additional 50μg/dl incremental doses of rocuronium were added to obtain grteater than 95% neuromuscular twitch inhibition. The ED5, ED50, ED90, and ED95 of rocuronium in each group were calculated using a probit model. Results: The ED50, ED90, and ED95 of rocuronium were significantly reduced in 5-HT 20μg/ml group (P ＜ 0.05), but no differences were observed with the other 5-HT groups compared to the control groups. Conclusions: 5-HT at 20μg/ml enhanced the neuromuscular blockade of rocuronium.

Effect of Intravenous Sildenafil on Pulmonary Hemodynamics and Gas Exchange in the Presence and Absence of Acute Lung Injury in Piglets

Sildenafil is becoming increasingly popular for the treatment of pulmonary hypertension. However, there are potential concerns regarding its effects on oxygenation and systemic hemodynamics that could theoretically reduce its utility in the neonatal population. We performed a prospective cumulative dose-response study of increasing doses of i.v. sildenafil (0.4, 1, and 3 mg/kg) on hemodynamics and oxygenation in 32 anesthetized piglets, of which 17 had meconium-induced pulmonary hypertension and lung injury, and 15 did not. Sildenafil caused a reduction in mean pulmonary artery pressure and pulmonary vascular resistance (PVR) at all doses, in non-lung-injured animals. There was no difference in pulmonary hemodynamics between doses. Oxygenation index [OI = mean airway pressure (cm H2O) * FiO2 * 100/PaO2 (mm Hg)] did not reach critical levels at any dose. In lung-injured animals, sildenafil also reduced mean pulmonary artery pressure and PVR by 30%. Again, this effect was achieved at the lowest dose, without subsequent changes at higher doses. However, in lung-injured animals, sildenafil produced a dose-related increase in oxygenation index. Sildenafil reduced the systemic vascular resistance (SVR) at the lowest dose in lung-injured animals, but this occurred only at higher doses in non-lung-injured animals. In conclusion, sildenafil is a potent pulmonary vasodilator. However, it should be administered with caution in the presence of lung injury because of a dose-related increase in oxygenation index and concomitant systemic vasodilatation.

Eosinophilic bronchitis in asthma: A model for establishing dose-response and relative potency of inhaled corticosteroids

Newer generations and formulations of inhaled corticosteroids have necessitated the development of a clinically relevant model to compare their clinical potency. We evaluated whether sputum eosinophil counts could demonstrate a dose-response to inhaled corticosteroids, and compared the response with other inflammatory markers. Fourteen steroid-naive patients with asthma with an initial sputum eosinophilia of > or = 2.5% entered a 6-week sequential, placebo-controlled, patient-blinded, cumulative dose-response study. After 7 days of placebo, they received incremental doses of fluticasone propionate (FP), 50, 100, 200, and 400 microg/d, each for 7 days. Measurements were made of sputum and blood eosinophils, exhaled nitric oxide, spirometry, airway responsiveness to methacholine (methacholine PC20), and symptom scores before and after each dose. Sputum eosinophils and exhaled nitric oxide were extremely sensitive to the effects of FP, and exhibited significant dose-dependent reductions of 99.4% and 99.8 parts per billion, respectively, where each variable was expressed per 100 microg/d FP. This compared with a 0.5 doubling dose increase of airway responsiveness to methacholine and a 0.3 decrease in symptom scores. Airway responsiveness to methacholine was the only variable that increased throughout the study. These results suggest that the model of eosinophilic bronchitis could be used to compare the effect of cumulative doses of an inhaled corticosteroid delivered by different types of delivery systems or preparations using a relatively small number of patients. Future clinical studies based on this model will allow clinicians to make informed decisions regarding the relative potencies of different inhaled corticosteroids.

Synthesis and bronchodilator activity of new quinazolin derivative

Taking lead from a naturally occurring quinazolin vasicine, a number of compounds were developed and evaluated for bronchodilator and anti-allergic activities. One of these compounds was 2,4-diethoxy-6,7,8,9,10,12-hexahydroazepino[2,1-b]quinazolin-12-one, hereinafter named 95-4, exhibited marked bronchodilator activity evaluated on contracted trachea or constricted tracheo-bronchial tree. On intestinal smooth muscle too it showed relaxant effect. Tracheal relaxant effect was not found to be mediated through β-adrenoceptors. Cumulative dose–response study with acetylcholine and histamine indicated for its non-specific direct effect on smooth muscles. 95-4 was found to be more potent than theophylline and less to that of salbutamol on dose basis. Tested by a number of experimental models, it was found devoid of anti-allergic activity. It was also found to be free from any adverse effect. 95-4 due to its marked bronchial muscle relaxant effect can find use in conditions associated with spasm of bronchial muscles.

Effects of Ondansetron and Granisetron on Rocuronium-induced Neuromuscular Blockade in a Rat Phrenic Nerve-hemidiaphragm Preparation

Background: Both ondansetron and granisetron exert their antiemetic effects via a blockade of the 5-hydroxytryptamine 3 receptor (). Because the is a member of a superfamily of ligand-gated ion channels and has structural similarities to the nicotinic acetylcholine receptor (nAChR), a antagonist may also inhibit the nAChR. This study examined the effects of antagonists, ondansetron and granisetron, on rocuronium-induced neuromuscular blockade in vitro. Methods: Rat phrenic nerve-hemidiaphragm preparations were isolated and allocated randomly into seven groups (control, 1, 10, 100/ml of ondansetron, 0.1, 1, 10/ml of granisetron). Two studies were carried out using single twitch responses. In the cumulative dose-response study, rocuronium 1/ml and each doses of ondansetron or granisetron were administered simultaneously, and incremental 0.5/ml doses of rocuronium were added to obtain more than 95% neuromuscular twitch inhibition. , , , and of rocuronium in each group were calculated using a logistic model. In the partial curarization study, the twitch heights were measured after administering ondansetron or granisetron (10 minutes after administering 3/ml rocuronium) and were measured 10 minutes later. The 2 twitch heights were then compared. Results: In the cumulative dose-response study, ondansetron 100/ml and granisetron 10/ml significantly reduced the of rocuronium (P ＜ 0.05). There were no intergroup differences in the partial curarization study. Conclusions: High concentration of ondansetron and granisetron enhanced the neuromuscular blockade of rocuronium. Granisetron enhanced the neuromuscular blockade of rocuronium more potently than ondansetron.

Role of sulfite additives in wine induced asthma: single dose and cumulative dose studies

BACKGROUNDWine appears to be a significant trigger for asthma. Although sulfite additives have been implicated as a major cause of wine induced asthma, direct evidence is limited. Two studies were...

Improved delivery of ipratropium bromide using Respimat®(a new soft mist inhaler) compared with a conventional metered dose inhaler: cumulative dose response study in patients with COPD

Respimat®(RMT) is a reusable, propellant-free, soft mist inhaler (SMI), a novel device for inhalation therapy. We conducted a three-period cross-over study to evaluate the safety and efficacy of cumulative doses of ipratropium bromide inhaled from RMT (Two dose levels) or from a pressurized metered dose inhaler (MDI), in 36 patients with chronic obstructive pulmonary disease (COPD). The bronchodilator effect of ipratropium bromide was greater when administered via RMT (10 or 20 μ g per puff, given double-blind within device, to total doses of 160 or 320 μ g) than via MDI (20 μ g per puff, total dose 320 μ g). The bronchodilator effects of the 160 and 320 μ g doses delivered via RMT were similar. Cumulative ipratropium bromide doses of 320 μ g given via MDI or RMT and 160μ g given via RMT produced similar safety profiles. Between 45 min after the first drug inhalation and 45 min after the final dose, greater bronchodilatory effect was obtained from half the cumulative dose of ipratropium (RMT 10 μ g per puff) when compared with the MDI (20 μ g per puff). Therefore, ipratropium bromide delivered by RMT is as safe as, and can be more effective than, the MDI on acute administration in patients with COPD.

Concepts of establishing clinical bioequivalence of chlorofluorocarbon and hydrofluoroalkane β-agonists

There are no established guidelines for judging equivalence between inhaled medications. The principles of establishing bioequivalence on the basis of bioavailability and pharmacokinetics may not be applicable to inhaled medications with predominantly topical and minimal systemic effects. For inhaled β 2-agonists, the most practical method of showing in vivo therapeutic equivalence is by comparing relative potencies (RPs) of pharmacodynamic effects (bronchodilation and bronchoprotection). A range of doses that includes placebo should be studied in an appropriate design with adequate sample size, and relative potency should be estimated. Hydrofluoroalkane and chlorofluorocarbon salbutamol are bioequivalent for both their bronchodilator (RP, 1.08; 90% confidence interval, 0.95%, 1.23%) and bronchoprotective effects (RP, 1.08; 90% confidence interval, 0.81%, 1.46%) with similar safety profile. Eighteen subjects are required in a cross-over design to demonstrate bronchoprotective bioequivalence with a confidence interval of 67% to 150% for the relative potency (80% power). For salbutamol, this can be achieved with a comparison of 100 and 200 μg doses. Twelve subjects would suffice for a cumulative dose-response study for bronchodilator bioequivalence. For both outcomes, repeatability and quality control of measurements have to be ensured for an accurate interpretation of the results. (J Allergy Clin Immunol 1999;104:S243-5.)

Cumulative Dose Response Study Comparing HFA-134a Albuterol Sulfate and Conventional CFC Albuterol in Patients with Asthma

As a result of the pending ban on chlorofluorocarbon production, the non-chlorofluorocarbon propellant 1,1,1,2-tetrafluoroethane (HFA-134a) is being evaluated as a replacement for CFCs in metered-dose inhalers. This cumulative dose response study compared the safety and bronchodilator efficacy of 16 cumulative inhalations of albuterol sulfate in an HFA-134a, CFC-free propellant system (108 microg of albuterol sulfate, equivalent to 90 microg of albuterol base) with that of equivalent doses of albuterol in a conventional CFC propellant system. Twenty-two patients with at least a 12-month history of stable asthma, who were currently taken an inhaled beta-adrenergic bronchodilator, and who had a FEV1 between 40% and 80% of predicted, were enrolled in this randomized, modified-blind, two-period crossover study. One, 1, 2, 4, and 8 inhalations of study drug were self-administered at 30-minute intervals, resulting in 16 cumulative inhalations. Pulmonary function and safety measures were assessed after each dosing interval. A significant dose response was found for HFA-134a albuterol sulfate and CFC albuterol with regard to changes in FEV1, serum potassium, heart rate, and blood pressure after 16 cumulative inhalations. No significant differences were demonstrated between HFA-134a albuterol sulfate and CFC albuterol for any FEV1 or safety parameter at any cumulative dose level. No clinically meaningful laboratory or physical examination abnormalities were found with administration of either HFA-134a albuterol sulfate or CFC albuterol. HFA-134a albuterol sulfate provides bronchodilation comparable to CFC albuterol and has a similar safety profile.

IN UTERO COCAINE EXPOSURE DECREASES NEONATAL CEREBRAL VASCULAR REACTIVITY IN GUINEA PIGS. † 1444

Although cocaine acutely increases cerebral vascular responsiveness, we hypothesized that fetuses, chronically exposedin utero to cocaine, would become desensitized and hyporeactive. To investigate, pregnant guinea pigs were injected daily with cocaine (12mg/kg sc) or saline control beginning midgestation. Newborn pups were studied after spontaneous delivery. Using video microscopy, the in vitro diameter change of newborn cerebral arteries (control: 290±18μm; 5±1days; cocaine-exposed: 295±8μm; 4±1day) in response to electrical field stimulation (EFS) or norepinephrine (NE) was assessed. After equilibration, a cumulative EFS or NE dose-response study was performed.In utero cocaine exposure decreased cerebral artery maximal EFS constriction 46% from 41±2% to 22±4% (p<0.01; n=14/group). Maximal NE-elicited vasoconstriction decreased 62%. EC50 values(sensitivity) of EFS and NE were unchanged. This study demonstrates thatin utero cocaine exposure decreases neonatal cerebral vascular reactivity. Thus, in utero cocaine exposure may have long-term consequences on neonatal cerebral vascular function. Supported by NIH grant DA07607. Figure

Cumulative Dose-Response Study of Non-CFC Propellant HFA 134a Salbutamol Sulfate Metered-Dose Inhaler in Patients With Asthma

This study compares the safety and efficacy of HFA 134a salbutamol sulfate (Airomir in the 3M CFC-free system [3M Pharmaceuticals]) and CFC 11/12 salbutamol (Ventolin [Allen & Hanburys]) in a cumulative dose-response (1, 1, 2, 4, 8 inhalations at 30-min intervals) study in asthmatic patients. Randomized, single-blind, two-period cross-over study. Twenty-four stable mild to moderate asthmatics. At all cumulative inhalations, the changes in FEV1 (absolute, percent, and percent predicted) and FVC were equivalent. There was also no significant difference in heart rate, serum potassium level, BP, 12-lead ECG, Holter monitor recordings, or adverse events. Both HFA 134a salbutamol sulfate and CFC 11/12 salbutamol displayed a significant dose-response for FEV1, FEF25-75%, FVC, serum potassium, heart rate, and systolic BP. HFA 134a salbutamol sulfate and CFC 11/12 salbutamol produced clinically and statistically similar airway responses and side effects. These results indicate that HFA 134a salbutamol sulfate would be a safe and effective substitute for CFC 11/12 salbutamol.

Dose-effect Relationship of the β-Agonists Fenoterol and Salbutamol in Patients With Asthma

What is the relative per microgram potency and side effect profile of the beta-agonists salbutamol and fenoterol? The relative bronchodilator (delta FEV1, V25, V50) potency and side effect profile (delta tremor, heart rate, breathlessness, BP) of nebulized salbutamol and fenoterol were evaluated by means of a randomized, double-blind, crossover, cumulative (50 to 2,500 micrograms) dose-response study. Both beta-agonists were administered to 12 patients with stable asthma over age 18 years with baseline FEV1 between 35 to 70 percent predicted. (1) Salbutamol and fenoterol both provided significant bronchodilatation compared with baseline. (2) There was no dose-effect difference between the two beta-agonists with respect to bronchodilator response. (3) Overall there was no significant difference between the side effect profiles of the two beta-agonists, although at the highest dose of fenoterol, there was marginally greater tremor when measured by accelerometry. (4) There was no difference in the vital signs or subjective patient evaluations of tremor, palpitations, or breathlessness as estimated by a visual analogue scale. (5) No significant adverse reactions occurred. Equivalent bronchodilatation and similar side effect profiles were measured in a group of patients with stable asthma after treatment with nebulized salbutamol or fenoterol in the dose range 50 to 1,250 micrograms (cumulative, 2,500 micrograms). This indicates that both beta-agonists have similar per microgram potency and side effect profiles. Observed clinical differences in response or side effects associated with fenoterol metered-dose inhaler administration may be a result of its higher dose per puff metered-dose inhaler formulation.

A Novel Orally Active Dopamine Prodrug TA-870. III. Positive Inotropic Effect and Cardiorenal Selectivity in Anesthetized Dogs

The effect of TA-870, a novel dopamine prodrug, on the cardiovascular system was studied in anesthetized open- and closed-chest dogs. Intraduodenal administration of less than or equal to 12 mg/kg TA-870 to anesthetized dogs increased left ventricular (LV) dP/dtmax and dP/dt/Pmax. Furthermore, at a lower dose of TA-870 (2 mg/kg), renal vascular resistance (RVR) decreased and renal blood flow (RBF) increased. Similarly, total peripheral resistance (TPR) decreased and cardiac output (CO) increased at less than 4 mg/kg. In an intravenous cumulative dose-response study of TA-870, the plasma-free-dopamine concentration was elevated depending on the dose of TA-870. Renal vasodilation occurred at a low plasma-free-dopamine concentration, whereas a positive inotropic action required higher plasma-free-dopamine. However, the dose-response curve for LVdP/dt/Pmax was steeper than that for RBF or CO. Heart rate was less affected than LVdP/dt/Pmax in open-chest dogs and decreased in closed-chest dogs. Propranolol strongly inhibited the effect of TA-870 on LVdP/dt/Pmax. It also inhibited the effects of TA-870 on TPR and CO to a lesser extent, and the remaining effects were almost completely inhibited by an additional treatment with the dopamine blocker, RS-sulpiride. In conclusion, TA-870 increased myocardial contractility and output by the enteral route, and the latter effect was produced at lower doses with the help of peripheral vasodilation due to the activation of dopamine receptors.

The bronchodilator response from inhaled terbutaline is influenced by the mass of small particles: a study on a dry powder inhaler (Turbuhaler)

This study was carried out to investigate if particles approximately less than 5 microns are optimal when delivered from a dry powder inhaler. It was performed as a cumulative dose response study of twelve asthmatic adults. Three different versions of a dry powder inhaler, Bricanyl Turbuhaler, were studied. Each inhaler delivered 0.5 mg of pure terbutaline sulphate with each dose. Out of this 0.5 mg, they delivered 90 micrograms, 40 micrograms and 5 micrograms, respectively, of particles approximately less than 5 microns with each dose at an inspiratory flow rate of 28 l.min-1. Terbutaline 0.5 mg, 0.5 mg, 1.0 mg and 2.0 mg was inhaled with a 30 min interval between the doses. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were measured 5 and 20 min after each dose. The bronchodilator response was greater with the inhaler delivering 90 micrograms of small particles with each dose than with the inhaler delivering 5 micrograms, thus confirming the importance of small (approximately less than 5 microns) particles.

METOCURINE REQUIREMENTS AND PALSMA CONCENTRATIONS IN BURNED PAEDIATRIC PATIENTS

A cumulative dose-response study for metocurine was performed on 11 burned and 11 non-burned children during thiopentone, nitrous oxide in oxygen and narcotic anaesthesia. Burned children required a significantly (P less than 0.001) greater dose (three-fold) of metocurine to achieve a given degree of neuromuscular blockade compared with non-burned children. For the same degree of twitch depression, burned children required twice the plasma concentration of metocurine. Despite the larger dose, the recovery time for the twitch was not significantly different in the two groups. It is speculated that there may be fundamental changes at the neuromuscular junction of burned children to account for their resistance to the effect of non-depolarizing neuromuscular blockers.