A comparison of triclosan and stannous fluoride toothpastes for inhibition of plaque regrowth. A crossover study designed to assess carry over

Some triclosan and stannous fluoride toothpastes have been shown effective in reducing plaque and more particularly gingivitis in home use studies. There have been few comparisons of such products for their chemical plaque inhibitory action divorced from the indeterminate variable of toothbrushing. This study was a randomised, single-blind, cross-over comparison of 4 products, in a 4-day plaque regrowth design, balanced for residual effects and involving 12 healthy dentate subjects. The test agents were a stannous fluoride toothpaste, a triclosan/copolymer toothpaste, a triclosan/zinc citrate toothpaste and water. On day 1 of each study period, subjects were rendered plaque free. For the following 4 days, each subject suspended normal toothcleaning and rinsed 2 x daily with the allocated treatment for 60 s under supervision. On day 5, plaque was scored by index. Washout periods of 2 1/2 days brushing with water alone, followed each treatment period. Pseudo treatment periods of 4 days, involving 2 x daily rinsing with water in the absence of toothbrushing, followed the normal washouts after the stannous fluoride and triclosan/zinc citrate treatments, giving a total of 6 treatment periods. This design permitted analyses for 1st-order-carry-over. Intention to treat analyses revealed all toothpastes were more effective than water but that there were no differences between the active treatments. Per protocol analysis gave essentially similar findings except that the difference in plaque in favour of the triclosan/zinc citrate toothpaste over water did not reach significance. There was no evidence of 1st-order-carry-over effects for the stannous fluoride or triclosan/zinc citrate toothpastes. Consistent with other studies it appears that stannous fluoride and triclosan can be formulated into toothpaste vehicles to provide plaque inhibitory effects.

Effect of calcium addition and acidification on the quality characteristics of canned okra (Hibiscus esculentus L)

A study was conducted on calcium chloride treatments of canned okra acidified by adding either acetic, citric, lactic, malic or tartaric acids or by lactic fermentation. The quality of the processed okra was determined by physical, chemical, microbiological and sensory analyses after a two month storage period at room temperature. The results indicated the possibility of processing high quality canned okra by small canneries, with low cost equipment and low energy requirements. The acidification procedures ensure minimal risk of botulism.

Clinical evaluation of tetracycline HCl conditioning in the treatment of gingival recessions. A comparative study

Thirty Class I and Class II recessions in 30 patients were treated with a modified subepithelial connective tissue graft procedure. Fifteen recessions in the test group received a tetracycline hydrochloride (50 mg/ml) root treatment for 5 minutes (TTC-HCl group); the remaining 15 recessions composed the control group and received a citric acid root treatment for 3 minutes (CA group). Clinical assessments were taken at baseline and at 6 months. The differences between treatments were not statistically significant. In the central area of the recession, the mean percentage of root coverage was 81.7% corresponding to a mean percentage of 79.3% and 84.0% for the TTC-HCl and the CA group, respectively. In the test group, 6 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 57.8%. In the control group, 8 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 43.6%. The mean surface area of root exposure was reduced from 11.53 mm2 and 13.30 mm2 to 0.34 mm2 and 0.29 mm2 for the TTC-HCl group and the CA group, respectively. This reduction corresponds to a mean percentage of 97.4% root coverage for both groups. Within the limits of this study, the results indicate that tetracycline hydrochloride and citric acid root conditioning have comparable clinical effects in root coverage surgical therapy. The data also suggest that the measurement of the surface area of the recession is a more accurate criterion in the evaluation of the mean percentage of root coverage than a single central vertical linear measurement.

Impairment of citrate metabolism in acute hepatic failure

AIMS

To compare the utilization of citrate employed as anticoagulant in patients with acute hepatic failure and subjects with normal liver function.

PATIENTS AND METHODS

Three patients in acute hepatic failure and normal renal function were studied during therapeutic plasma exchange with citrate containing fresh frozen plasma. Six patients receiving immunapheresis or LDL-apheresis anticoagulated with citrate served as controls. Determinations of serum citrate concentrations, of ionized calcium and blood pH were performed before, during, and after the extracorporeal treatment. Total body clearance and elimination half life were calculated in a two compartment model.

RESULTS

Preinfusion citrate levels were higher in the patients with acute hepatic failure than in the controls (n.s.). The citrate level rose to 1.73 +/- 0.2 mmol/l in the liver patients versus 0.99 +/- 0.1 mmol/l in the healthy subjects (p < 0.03). Total body clearance was markedly reduced in patients with acute hepatic failure (3.31 +/- 0.03 ml/kg/min) as compared with the controls (6.34 +/- 0.16 ml/kg/min) (p < 0.02), the elimination half life (t/2 k1e) was prolonged (49.7 +/- 5.4 vs. 32.9 +/- 1.02 min, p < 0.05). In the controls blood pH rose from 7.4 +/- 0.01 to 7.45 +/- 0.01 (p < 0.05) after citrate infusion, whereas in the liver patients no rise in pH was observed, again reflecting the impairment of citrate metabolism. Ionized calcium was lower in the patients with acute hepatic failure at the beginning (1.01 +/- 0.05 vs. 1.21 +/- 0.04 mmol/l, p < 0.05) and the end (0.68 +/- 0.02 vs. 0.93 +/- 0.04 mmol/l, p < 0.05) of the citrate infusion.

CONCLUSIONS

Citrate metabolism is severely impaired and the plasmatic calcium stores are reduced in acute hepatic failure and, thus, the risk of adverse effects is high. Therapeutic infusions of citrate should be restricted in patients with acute hepatic failure and, if necessary, therapy should be closely monitored by repeated measurements of ionized calcium to avoid the development of potentially hazardous hypocalcemia.

Circulatory kinetics of intravenously injected 238Pu(IV) citrate and 14C-CaNa3-DTPA in mice: comparison with rat, dog, and reference man

New ligands for in vivo chelation of Pu(IV) are being synthesized and evaluated in mice for efficacy and toxicity. Biokinetic studies of the new ligands, CaNa3-DTPA, and Pu(IV) are major components of those investigations. Young adult female mice were injected intravenously (iv) with 3H-inulin, 14C-CaNa3-DTPA, or 238Pu(IV) citrate to provide baseline data for plasma clearance, tissue uptake, and excretion rates and to determine the dilution volume (VOD) and renal clearance rate (RC) of filterable substances. Published plasma clearance data for iv-injected 14C-CaNa3-DTPA and Pu(IV) citrate in Reference Man, dog, and rat were collected. Based on combined data for 3H-inulin and 14C-CaNa3-DTPA, VOD = 17% of body weight and RC = 18 mL kg(-1) min(-1) for mice. Retention of 14C-CaNa3-DTPA in the four species is proportional to body weight and inversely proportional to RC: Integrals of the retention of 14C-CaNa3-DTPA from R(t) = 1.0 to R(t) = 0.05 are 108, 43, 28, and 10 DF min, respectively, for Reference Man, dog, rat, and mouse. Clearances of iv-injected Pu(IV) citrate from plasma are in the same order: The plasma curve integrals from injection to 1440 min are 840, 640, 280, and 67 DF min, respectively, for Reference Man, dog, rat, and mouse. In mice, a large fraction of newly injected Pu(IV) is rapidly transferred to the interstitial water of bulk soft tissue (excluding liver and kidneys), from which it is cleared at the same rate as from the plasma. Rapid plasma clearance, escape into interstitial water (22%ID at 20 min), significant early urinary excretion (8%ID in 12 h), and prompt deposition in liver and skeleton (complete in 12 h) are evidence of inefficient binding to plasma protein (mainly transferrin) of newly injected Pu(IV) in mice. Conversely, slow plasma clearance, little early urinary excretion, and delayed deposition in liver and skeleton reflect more efficient binding by transferrin of newly injected Pu(IV) in Reference Man and dog. Pharmacokinetic parameters (effective dosage, effective concentration) of CaNa3-DTPA, alone or combined with plasma Pu(IV) integrals, yielded only qualitative predictions of the relative efficacies of CaNa3-DTPA therapy in four species. The need for improved models of Pu(IV) and ligand biokinetics and the suitability of the three animals for predicting chelation therapy outcomes in humans are discussed.

Effect of bran, ispaghula, and inert plastic particles on gastric emptying and small bowel transit in humans: the role of physical factors

BACKGROUND

Coarse bran is known to accelerate transit through the whole gut and to increase stool weight. This effect is much reduced by grinding the bran, suggesting that particle size influences gut motor patterns.

AIMS

To compare the effect of 15 g coarse bran with 15 g inert plastic particles and 7 g of ispaghula on the gastric emptying and small bowel transit of a rice pudding test meal.

SUBJECTS

13 healthy volunteers.

METHODS

Transit of 99mTc labelled rice studied by gamma-scintigraphy measuring gastric emptying and colonic arrival over 10 hours. Small bowel transit was estimated from the difference between time to 50% gastric emptying and 50% colonic arrival.

RESULTS

Bran delayed gastric emptying by 22 (SEM 8) minutes compared with control values of 88 (SEM 6) minutes p < 0.05. Ispaghula and plastic particles had no significant effect. Small bowel transit was accelerated compared with control values of 322 (SEM 29) minutes, decreasing by 95 (29) minutes and 62 (22) minutes after bran and plastic particles respectively. Ispaghula again showed no significant effect.

CONCLUSION

Coarse bran delays gastric emptying and accelerates small bowel transit. The marked acceleration of small bowel transit also seen with inert plastic particles may be due to increased upper gut secretions after stimulation of enteric nerves.

Mitomycin C dissolved in a reversible thermosetting gel: target tissue concentrations in the rabbit eye

AIMS

To determine whether a new, reversible thermosetting gel enhances mitomycin C transfer to target ocular tissues in the rabbit eye.

METHODS

A 0.1 ml solution of mitomycin C containing 0.22 microgram, 2.9 micrograms, or 28 micrograms of the agent dissolved in a reversible thermosetting gel consisting of methylcellulose, citric acid, and polyethylene glycol was injected subconjunctivally in 30 New Zealand albino rabbits. Scleral and conjunctival tissues were excised at 0.5, 1, 2, 4, or 24 hours after the injection and mitomycin C concentrations in these tissues were determined by high performance liquid chromatography. The concentration over time was approximated to a single exponential curve, and initial mitomycin C concentrations, time constants, and half life values were determined. Finally, the areas under the curves (AUCs) between 0.5 and 24 hours were calculated.

RESULTS

The mitomycin C concentrations in the target tissues were dose dependent and decreased rapidly over 24 hours. Both the initial mitomycin C concentrations as well as AUCs in these eyes treated with mitomycin C, dissolved in a reversible thermosetting gel, were higher than those in eyes treated similarly in a previous study in which the gel was not used.

CONCLUSION

Applied subconjunctivally in the rabbit eye, mitomycin C dissolved in the reversible thermosetting gel enhanced transfer of the agent to the sclera and the conjunctiva.

Sodium metabisulfite and citric acid induce bronchoconstriction via a sulfite-sensitive pathway in the isolated guinea pig lung

Inhalation of sodium metabisulfite (MBS; 80 mM; pH 2.9 +/- 0.1) or citric acid (CA; 0.4 M; pH 2.0 +/- 0.1) aerosols induced a reduction in compliance and conductance in the isolated perfused and ventilated guinea pig lung without affecting perfusion flow. The effect was dependent on the pH of the nebulized solution since inhalation of 80 mM MBS aerosols at pH 7.4 did not induce any effect on bronchial tone. Concomitantly to the bronchoconstriction induced by MBS or CA an increased level of calcitonin gene-related peptide (CGRP-LI) in the effluent perfusate was observed, indicating activation of sensory nerves. Sodium sulfite, a dissolution product of MBS, has previously been shown by our studies to reduce bronchoconstriction induced by inhalation of sulfur dioxide, in the isolated perfused and ventilated guinea pig lung. In the present study perfusion of the lung with sodium sulfite (3 mM) before and during exposure to aerosols with either MBS or CA attenuated the bronchoconstriction induced by the acidic solutions. The release of CGRP-LI induced by MBS or CA was not affected by sodium sulfite. Sulfite treatment did not modify perfused guinea pig lung reactivity towards acetylcholine (4 nmol), bradykinin (100 pmol), histamine (10 nmol), serotonin (500 pmol) and substance P fragment 5-11, a substance P analogue resistant to degrading enzyme (500 pmol). However, an inhibitory effect by sodium sulfite was observed on bronchoconstriction induced by the NK-2 agonist neurokinin A fragment 4-10 (NKA 4-10, 25 pmol). These results indicate that MBS- or CA-induced bronchoconstriction was dependent on the low pH of the aerosol solution and coincided with activation of sensory nerves. Sulfite modulation of the bronchoconstricting action of inhaled MBS and CA is suggested to be related to a sulfite-sensitive step in the signal transduction of the neuropeptide NKA.

Continuous monitoring of salivary flow rate and pH at the surface of the dentition following consumption of acidic beverages

Use of a splint-mounted flexible pH electrode has allowed reliable continuous monitoring of pH at the surface of the dentition whilst still enabling subjects to drink normally. pH was monitored at the palatal upper left central incisor and upper right first permanent molar sites after drinking 1% (w/v) citric acid. A maximal decrease in pH to values of 2-3 was observed after 1 min followed by a slower recovery which was above pH 5.5 within 2 min at the former site and in 4-5 min at the latter site. A sharp rise in parotid saliva flow rate was seen at 1 min after drinking the same concentration of citric acid by glass, straw or feeder cup, which returned to resting levels within 6 min although the fall-off of flow rate was slower with the feeder cup. Thus, after dietary acid intake the pH at the surface of the dentition is below the critical pH for enamel dissolution for shorter periods than previously suggested, which is probably a reflection of salivary neutralisation and washing.

Retention and utilization of amino acids in piglets fed ad libitum or restrictively diets supplemented with organic acids

In a metabolic trial 4 groups of 8 piglets of 5 kg weight each were kept individually for 45 days (final weight 23 kg) and fed a practical diet. At the beginning of the experiment the body amino acid contents of an additional group of 8 piglets were determined by carcass analysis, and at the end of the experiment the body amino acid contents of the 4 test group piglets (A = control fed ad libitum, B and C = supplement of 1.5% fumaric acid fed ad libitum or restrictively, D = supplement of 1.5% citric acid fed ad libitum) were also analysed. The amino acid retention during the experimental period was determined by difference. The supplements of fumaric or citric acid did not influence the amount of the amino acid retention. The quotient of amino acid retention to amino acid consumed or the "productive amino acid value" was calculated and the maintenance requirements of essential amino acids for piglets were used to estimate the productive amino acid value for both retention and maintenance. The mean amino acid retention amounted to about 56 g/d, i.e. 3.49 g/kg W0.75.d of essential amino acids. The essential amino acid requirements for maintenance was 2.0 g, i.e. 0.29 g/kg W0.75.d, showing a variation of 4% (Leu) to 20% (Met+Cys) when related to the amount of the corresponding amino acid retention. With regard to the amino acid pattern for retention of the nutritionally most important amino acids, the following ratios were found: Lys, 100 (6.27 g/16 g N): Met+Cys, 48 (3.03 g): Thr, 56 (3.49 g): Trp, 13 (0.80 g). The productive amino acid values ranged from 40% (Trp), 55% (Thr), 66% (Met) to 80% (Lys). Under the conditions investigated, neither the supplements of organic acids nor the feed restriction influenced the amino acid utilization.

Intake of ethanol, sodium chloride, sucrose, citric acid, and quinine hydrochloride solutions by mice: a genetic analysis

Mice of the 129/J (129) and C57BL/6ByJ (B6) strains and their reciprocal F1 and F2 hybrids were offered solutions of ethanol, sucrose, citric acid, quinine hydrochloride, and NaCl in two-bottle choice tests. Consistent with earlier work, the B6 mice drank more ethanol, sucrose, citric acid, and quinine hydrochloride solution and less NaCl solution than did 129 mice. Analyses of each generation's means and distributions showed that intakes of ethanol, quinine, sucrose, and NaCl were influenced by a few genes. The mode of inheritance was additive in the case of ethanol and quinine, for sucrose the genotype of the 129 strain was recessive, and for NaCl it was dominant. Citric acid intake appeared to be influenced by many genes with small effects, with the 129 genotype dominant. Correlations of sucrose consumption with ethanol and citric acid consumption were found among mice of the F2 generation, and the genetically determined component of these correlations was stronger than the component related to environmental factors. The genetically determined correlation between sucrose and ethanol intakes is consistent with the hypothesis that the higher ethanol intake by B6 mice depends, in part, on higher hedonic attractiveness of its sweet taste component.

Inhalation cough challenge in the investigation of the cough reflex and antitussives

Inhalation cough challenge is a useful tool in the physiological and pharmacological investigation of the cough reflex. There are three types of challenge used, capsaicin and the vanilloids, organic acids, and distilled water challenge. In addition, challenge may be administered in a single dose or cumulative dose fashion. The correct combination of inhalation technology and tussive stimulus produces a sensitive and specific method for estimating the cough reflex.

Improving the palatability of oral rehydration solutions has implications for salt and water transport: a study in animal models

It is believed that improving the taste of oral rehydration solutions (ORSs) might lead to greater patient acceptability. A pilot trial showed that replacing glucose with sucrose and increasing the citrate concentration at the expense of chloride improves palatability. However, the transport implications of such modifications are not known. Three hypotonic experimental ORSs (Suc/cit-ORS, 211 mosmol/kg; Suc/Cl-ORS, 224 mosmol/kg; and Glu-ORS, 224 mosmol/kg) were compared with a standard European ORS (Euro-ORS, 265 mosmol/kg) by in vivo perfusion of entire rat small intestine in normal adult rats and rotavirus-infected neonates. All ORSs were of identical sodium, potassium, chloride, and citrate content except that in the Suc/cit-ORS, chloride was removed in favor of increased citrate, and the chloride concentration in Euro-ORS was higher than in the others. Suc/cit-ORS and Suc/Cl-ORS had glucose partially replaced by sucrose while Glu-ORS and Euro-ORS contained only glucose. In normal small intestine, water absorption was greater from Glu-ORS than Suc/cit-ORS or Euro-ORS, although water absorption was similar from Suc/cit-ORS and Suc/Cl-ORS. In the rotavirus model, Glu-ORS produced more water absorption than Euro-ORS or either sucrose ORS. In both models, Suc/cit-ORS caused sodium and chloride secretion. Glucose absorption was similar from all ORSs. These findings indicate that attempts to improve ORS palatability by adding sucrose or increasing citrate at the expense of chloride would incur a significant penalty in terms of salt and water absorption.

Mechanism of irritant-induced cough: studies with a kinin antagonist and a kallikrein inhibitor

It has been suggested that bradykinin may play a role in stimulating cough in at least one pathological condition in humans. We have employed an animal model to investigate the possible role of this peptide in irritant-induced cough. The kinin antagonist Hoe 140 and codeine both produced dose-related inhibition of cough responses to inhalation of citric acid or bradykinin aerosols by conscious guinea pigs. The selective tissue kallikrein inhibitor CH694 inhibited cough caused by citric acid but not by bradykinin. Indomethacin pretreatment attenuated the responses to both stimuli as did phosphoramidon. It is concluded that cough produced by citric acid inhalation may be mediated, at least in part, by generation of kinins; secondary to this, a release of prostanoids also appears to participate in the response.

Calcium absorption from apple and orange juice fortified with calcium citrate malate (CCM)

OBJECTIVE

Determine calcium (Ca) absorption from Ca fortified orange and apple juice.

METHODS

Absorbability was assessed by measuring 45Ca absorption in healthy women (mean age 57 years, n = 57/group) and whole body 47Ca retention in adult female beagle dogs (n = 6/group) and young adult male rats (n = 6/group). Women received 6.24 mmol (250 mg) Ca as calcium citrate malate fortified orange juice (CCM-OJ) or apple juice (CCM-AJ). Dogs received 3.12 mmol (125 mg) Ca as CCM-OJ or CCM-AJ. Rats were administered 0.15 mmol (6 mg) Ca as either milk, CCM-OJ, or CCM-AJ. Additional 47Ca whole body retention experiments in rats measured the effects of differences in the carbohydrate and organic acid contents of the juices on Ca absorption.

RESULTS

Mean +/- SEM percent Ca fractional absorption was greater (p < 0.003) in women who consumed CCM-AJ (42 +/- 2%) than those who consumed CCM-OJ (36 +/- 1%). Ca retention in dogs was 15 +/- 1% for CCM-OJ and 29 +/- 2% for CCM-AJ (p < 0.001). Ca retention was significantly different (p < 0.05) in rats administered milk (42 +/- 2%), CCM-OJ (52 +/- 2%), or CCM-AJ (61 +/- 2%). By manipulating the carbohydrate and organic acid concentrations of test solutions to mimic the composition of Ca fortified juices, we found that the greater fructose and lower organic acid content of apple juice accounted for its greater Ca absorbability.

CONCLUSIONS

CCM fortified versions of orange and apple juice have high Ca absorbability and are potentially important vehicles for increasing dietary Ca intake. The greater Ca absorption from CCM-AJ compared with CCM-OJ is accounted for by differences in the carbohydrate and organic acid content of the juices. These data suggest that by modifying common beverage ingredients, products with even greater Ca absorbability could be formulated.

Changes in taste perception following mental or physical stress

Taste perception depends not only on the chemical and physical properties of tastants, but may also depend on the physiological and psychological conditions of those who do the tasting. In this study, the effects of mood state on taste sensitivity was evaluated in humans who were exposed to conditions of mental or physical fatigue and tension. Taste responses to quinine sulfate (bitter), citric acid (sour) and sucrose (sweet) were tested. The intensity of the taste sensations were recorded by a computerized time-intensity (Tl) on-line system. Subjects performed mental tasks by personal computer or physical tasks by ergometer for 10-40 min. Before and after these sessions, the duration of the after-taste and the intensity of the sensation of taste were recorded by the Tl system, and in addition, psychological mood states were evaluated with POMS (Profile of Mood State). Tl evaluation showed that after the mental tasks, the perceived duration of bitter, sour and sweet taste sensations was shortened relative to the control. Total amount of bitterness, sourness and sweetness was also significantly reduced. Furthermore, the maximum intensity of bitterness was significantly reduced. There were no significant differences in bitterness and sweetness sensations following physical tasks. However, relative to before the physical task, the duration of the after-taste of sourness was significantly shortened by the physical task. After the physical task, the buffering capacity of saliva was significantly increased. Thus mental and physical tasks alter taste perception in different ways; the mechanisms underlying these changes remain to be determined.

Anterior tongue stimulation with amiloride suppresses NaCl saltiness, but not citric acid sourness in humans

Suppression of the saltiness of NaCl solutions by amiloride, a sodium channel blocker, has previously been reported a number of times in humans. This suppression was seen with techniques that involved stimulation of small areas of the tongue. It was not certain, however, whether amiloride would suppress saltiness with stimulation of a much larger area of the tongue; one published study, in fact, found negative results with whole mouth stimulation. For this study, eight subjects dipped a large part of the anterior portion of the tongue into a 10-ml sample of NaCl solution, or a NaCl and amiloride solution, and reported its magnitude of saltiness intensity. The results show that amiloride suppressed the saltiness of NaCl when a large area of the anterior tongue was stimulated. Consistent with previous studies, there was individual variability across subjects in this suppressive effect of amiloride. This study also used this method to test the effects of amiloride on the sourness of citric acid, which was not expected to be affected. No suppression of sourness was seen with amiloride.

Does root surface conditioning with citric acid delay healing?

Effects of topical citric acid application on tissue maturation was studied in standardized periodontal defects in 6 beagle dogs. Following elevation of facial mucoperiosteal flaps, fenestration defects, 3 mm in diameter, were made through the cortical bone and recessed 0.5 mm into the dentin of maxillary canines. 1 defect in each dog was conditioned with a saturated solution of citric acid for 3 min and then rinsed with saline. Control defects in contralateral teeth were treated with saline only for the same length of time. The defects were covered with an expanded polytetrafluoroethylene membrane and the flaps repositioned and sutured. 14 days postsurgery, healing appeared more advanced along the defect walls and floor than in the center of the defect in all instances. Histometrically, citric acid-conditioned defects exhibited a higher density of collagen fibers along the defect walls and floor and adjacent to the barrier membrane as well as more advanced resolution of the residual blood clot than the surgical controls. Differences in fibroblast density within specimen pairs were non-significant. All control defects but none of the acid-conditioned defects showed an artifactual split between the dentin walls and the granulation tissue. This study failed to support the contention that topical application of citric acid to root surfaces may delay healing following periodontal surgery.

Antitussive activity of moguisteine enantiomers in guinea-pigs and rats

The antitussive effect of the R-(+)- and S-(-)-enantiomers of moguisteine were evaluated in comparison with the racemate in cough induced by 7.5% citric acid and 30 microM capsaicin aerosol in conscious guinea-pigs. No difference in potency was observed between moguisteine and the enantiomers. The oral ED50 values (with 95% confidence limits) for moguisteine, R-(+)- and S-(-)-enantiomers were respectively: 20.4 (12.9-26.6), 20.9 (14.9-26) and 21.6 (11.8-30.0) mg/kg-1 in cough provoked by citric acid and 17.7 (12.5-29.8), 18.9 (14.1-30.1) and 20.5 (15.1-36.6) mg/kg-1 in cough induced by capsaicin. The acute oral and intraperitoneal toxicities of the enantiomers and moguisteine in the rat are very similar. These findings suggest that the use of either enantiomer does not offer any advantage over the racemate.