The Antitussive Benzonatate Is Not Tumorigenic in Rodent Carcinogenicity Studies.

Benzonatate is a peripheral oral antitussive that dampens the activity of cough stretch receptors. Rodent carcinogenicity studies were performed in Tg.rasH2 mice and Wistar Han rats. Mice were orally gavaged benzonatate at 10, 30, 75, and 100 mg/kg/day for males and 5, 15, and 50 mg/kg/day for females. Rats were gavaged at 10, 30, and 90 mg/kg/day for males and 5, 15, and 50 mg/kg/day for females. Higher doses in males were due to differences in maximum tolerated doses in dose-ranging studies. In both species, benzonatate was not detected in plasma because of rapid ester hydrolysis producing 4-(butylamino) benzoic acid (BBA) and methylated polyethylene glycol polymer. This metabolism was similar in human plasma; therefore, plasma BBA was used to show systemic exposure. Both species had no evidence of a benzonatate-related increase in any neoplasm. A slight increase in nasal cavity exudative inflammation was present in benzonatate-dosed male mice. Retinal atrophy was observed in male rats at ≥30 mg/kg/day, but the incidence was within historical control data range and not related to benzonatate. In conclusion, benzonatate and its 2 major metabolites were not carcinogenic in rodent carcinogenicity studies at BBA exposures of ≥32 and 70 times a 200 mg human benzonatate dose, respectively.

High-dose dextromethorphan produces myelinoid bodies in the hippocampus of rats.

Dextromethorphan (DM) administered at supra-antitussive doses produce psychotoxic and neurotoxic effects in humans. We administered DM (80 mg/kg) to rats intraperitoneally to determine the ultrastructural change induced by DM, because intraperitoneal route is sensitive for the behavioral responses. Treatment with DM resulted in mitochondrial dysfunction and formation of myelinoid bodies in the hippocampus. MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate] attenuated DM-induced cytosolic oxidative burdens. However, neither MK-801 nor naloxone affected DM-induced mitochondrial dysfunction and formation of myelinoid bodies, indicating that the neurotoxic mechanism needs to be further elucidated. Therefore, the spectrum of toxicological effects associated with DM need to be reassessed.

Developmental toxicity of dextromethorphan in zebrafish embryos/larvae.

Dextromethorphan is widely used in over-the-counter cough and cold medications. Its efficacy and safety for infants and young children remains to be clarified. The present study was designed to use zebrafish as a model to investigate the potential toxicity of dextromethorphan during embryonic and larval development. Three sets of zebrafish embryos/larvae were exposed to dextromethorphan at 24, 48 and 72 h post fertilization (hpf), respectively, during the embryonic/larval development. Compared with the 48 and 72 hpf exposure sets, the embryos/larvae in the 24 hpf exposure set showed much higher mortality rates which increased in a dose-dependent manner. Bradycardia and reduced blood flow were observed for the embryos/larvae treated with increasing concentrations of dextromethorphan. Morphological effects of dextromethorphan exposure, including yolk sac and cardiac edema, craniofacial malformation, lordosis, non-inflated swim bladder and missing gill, were also more frequent and severe among zebrafish embryos/larvae exposed to dextromethorphan at 24 hpf. Whether the more frequent and severe developmental toxicity of dextromethorphan observed among the embryos/larvae in the 24 hpf exposure set, as compared with the 48 and 72 hpf exposure sets, is due to the developmental expression of the phase I and phase II enzymes involved in the metabolism of dextromethorphan remains to be clarified. A reverse transcription-polymerase chain reaction analysis, nevertheless, revealed developmental stage-dependent expression of mRNAs encoding SULT3 ST1 and SULT3 ST3, two enzymes previously shown to be capable of sulfating dextrorphan, an active metabolite of dextromethorphan.

Investigation of antitussive and toxicological activity of Ballota limbata in mice.

CONTEXT: Ballota limbata Benth. (Lamiaceae) (syn, Otostegia limbata Hook.f.) is a species grown in the North West Frontier Province and the lower hills of West Punjab, Pakistan. Ballota species are renowned for their antispasmodic, antiulcer, diuretic, vermifuge, and especially sedative effects. However, little is known about the biological activity of B. limbata. OBJECTIVE: Evaluation of antitussive activity and safety profile of dried B. limbata extract. MATERIALS AND METHODS: Whole air-dried plants were partitioned with various solvents and the butanol fraction was subjected to antitussive evaluation using a sulfur dioxide (SO(2))-induced cough model in mice. Codeine and dextromethorphan were used as positive control. Safety profile of the testing material was established using standard toxicity tests. RESULTS: B. limbata extract inhibited cough provoked by SO(2) gas in mice in a dose-dependent manner. The extract exhibited maximum protection against SO(2)-induced cough after 60 min of administration. B. limbata offered maximum cough suppressive effects, that is, number of coughs during 60 min was 11.66 ± 1.2 (mean ± SEM), after s.c. administration of 800 mg/kg, as compared with codeine 10 mg/kg, s.c., dextromethorphan 10 mg/kg, s.c., and saline showing a frequency of cough of 11.75 ± 1.18, 12.25 ± 0.83, and 46.25 ± 1.52, respectively. LD(50) value of B. limbata was greater than 5000 mg/kg. No sign of neural impairment was observed at antitussive doses and the extract has been well-tolerated at higher doses. DISCUSSION AND CONCLUSION: This study demonstrates that the extract of B. limbata has shown strong cough suppressive effect in mice without yielding any notable toxicity.

A comparative assessment of acute oral toxicity and traditional pharmacological activities between extracts of Fritillaria cirrhosae Bulbus and Fritillaria pallidiflora Bulbus.

ETHNOPHARMACOLOGICAL RELEVANCE: Fritillariae Bulbus ("Beimu" in Chinese) is a famous traditional Chinese medicine used to treat cough, expectoration and asthma for more than 2000 years, which belongs to the Fritillaria genus in Liliaceae family. Bulbs of Fritillaria cirrhosa D.Don (BFC) and bulbs of Fritillaria pallidiflora Schrenk (BFP) are two important drugs of Beimu. Due to the significant similarities in their outward appearance characters and chemical profiles, BFC has often been adulterated with BFP in Chinese Traditional Medicine markets. AIM OF THE STUDY: This study aims to compare the oral acute toxicity and the traditional pharmacological activities including antitussive, expectorant and anti-inflammatory effects between the extract of BFC and BFP, to clear and definite if the BFP can be used as a substitute of the BFC in the application of traditional medicine. MATERIALS AND METHODS: The extracts were prepared through refluxing with 80% ethanol solvent. For the acute toxicity tests, graded doses of BFP extracts and the maximum dose of BFC extracts were administered orally to mice. The animals were observed for toxic symptoms and mortality daily for 14 days. For the pharmacological activities tests, graded doses of BFP and BFC extracts were administered orally to mice. To observe the effects relieving cough, expelling phlegm and lessening the ear swelling of BFC extracts and BFP extracts through ammonia liquor inducing cough, phenol red apophlegmating in mice and the xylene-induced auricular swelling of mouse, respectively. RESULTS: In the acute toxicity study, the LD50 value of BFP in mice was calculated to be 213.57 g/kg body weight, and the maximum feasible dose (MFD) value of BFC in mice was 452.14 g/kg. Histopathological analysis has shown inflammatory cells infiltration and cells edema in liver, multinucleated giant cell proliferation in spleen, perivascular exudate and hemorrhage in lung, glomerulus atrophy in kidney of mice after oral administrations of BFP extracts. But only liver cells edema was observed in BFC group. Both BFC extract and BFP extract significantly increased latent period of cough and inhibited cough frequency in mice induced by ammonia. Besides, the two extracts also obviously enhanced mice's tracheal phenol red output in expectorant assessment and inhibited the development of ear edema in anti-inflammatory evaluation assay. CONCLUSION: To summarize, the BFP has the significant similarities in morphological characteristics, chemical profiles and traditional pharmacological activities compared with the BFC. The result of this study provide some valid scientific support for using BFP as a plant substitute of the BFC, but considering the toxicity of BFP is much higher than BFC, we don't recommend long-term oral administration of BFP or exceeding recommended dosage of Chinese Pharmacopoeia 2015.

Effects of common antitussive drugs on the hERG potassium channel current.

A common over-the-counter (OTC) non-opioid antitussive drug, clobutinol, was recently withdrawn from the market due to its potential to induce cardiac arrhythmias by a blockade of the potassium channel coded by the human ether-à-go-go-related gene (hERG). In this study, we investigated the effects of a number of antitussive compounds on the hERG ion channel current using patch-clamp electrophysiology, and compared the effects to that of clobutinol. The compounds clobutinol, pentoxyverine, dextromethorphan, and codeine inhibited the outward current in hERG transfected cells with half-maximal inhibition concentrations (IC50) of 1.9 microM, 3.0 microM, 5.1 microM, and 97 microM, respectively. For theobromine, no significant effect on the hERG current at a concentration up to 100 microM was detected. Safety margins between the effects of the drugs on the hERG ion channel current and their calculated maximal free therapeutic plasma concentration were calculated. These results were compared to assess potential risks of the compounds to induce torsade de pointes-type arrhythmias.

Genotoxicity assessment of the novel antitussive agent Benzonatate and its major metabolite.

Benzonatate (TESSALON®) is a peripherally acting oral antitussive. It undergoes rapid ester hydrolysis producing 4-(butylamino) benzoic acid (BBA) and methylated polyethylene glycol (MPG) metabolites, which are eliminated in urine and feces. The nonclinical and clinical efficacy of Benzonatate has been demonstrated over the last 60 years, but its safety was not fully assessed. In this study, we tested the genotoxicity of Benzonatate and its major metabolite BBA in an in vitro bacterial reverse mutation and in vivo micronucleus assays. A chromosomal aberration assay was also performed on Benzonatate and BBA. In the reverse mutation assay, Benzonatate and BBA doses 1.5-5000 µg/plate ±â€¯S9 metabolic activation were used and the numbers of revertants/plate were compared to various controls. Chromosomal aberration assays with human peripheral blood lymphocytes used Benzonatate and BBA concentrations 25-2000 and 62.5-1930 µg/mL, respectively. A CByB6F1 mouse bone marrow micronucleus assay was performed as part of a 28-day oral toxicology study at up to 250 mg/kg/day. The frequencies of micronuclei in polychromatic erythrocytes in treated groups were compared with the control group. Neither Benzonatate nor BBA induced significant mutagenicity in any of the bacterial strains, with or without metabolic activation. They also did not produce any biologically relevant structural or numerical aberrations in human chromosomes. Benzonatate and its BBA and MPG metabolites rapidly produced from esterase activity did not produce any significant increase in the incidence of micronucleated polychromatic erythrocytes. In conclusion, Benzonatate and its major metabolite BBA were not mutagenic and did not cause numerical or structural chromosome alterations. While the MPG metabolite was not tested, studies on structural analogues indicated it was also unlikely to be genotoxic. This was supported by oral rodent carcinogenicity assays showing no increase in malignancies.

Effects of dextromethorphan on dopamine dependent behaviours in rats.

Dextromethorphan, a noncompetitive blocker of N-methyl-D- aspartate (NMDA) type of glutamate receptor, at 7.5-75 mg/kg, ip did not induce oral stereotypies or catalepsy and did not antagonize apomorphine stereotypy in rats. These results indicate that dextromethorphan at 7.5-75 mg/kg does not stimulate or block postsynaptic striatal D2 and D1 dopamine (DA) receptors. Pretreatment with 15 and 30 mg/kg dextromethorphan potentiated dexamphetamine stereotypy and antagonised haloperidol catalepsy. Pretreatment with 45, 60 and 75 mg/kg dextromethorphan, which release 5-hydroxytryptamine (5-HT), however, antagonised dexamphetamine stereotypy and potentiated haloperidol catalepsy. Apomorphine stereotypy was not potentiated or antagonised by pretreatment with 7.5-75 mg/kg dextromethorphan. This respectively indicates that at 7.5-75 mg/kg dextromethorphan does not exert facilitatory or inhibitory effect at or beyond the postsynaptic striatal D2 and D1 DA receptors. The results are explained on the basis of dextromethorphan (15-75 mg/kg)-induced blockade of NMDA receptors in striatum and substantia nigra pars compacta. Dextromethorphan at 15 and 30 mg/kg, by blocking NMDA receptors, activates nigrostriatal dopaminergic neurons and thereby potentiates dexampetamine stereotypy and antagonizes haloperidol catalepsy. Dextromethorphan at 45, 60 and 75 mg/kg, by blocking NMDA receptors, releases 5-HT and through the released 5-HT exerts an inhibitory influence on the nigrostriatal dopaminergic neurons with resultant antagonism of dexampetamine stereotypy and potentiation of haloperidol catalepsy.

Protective effect of Lycium Barbarum polysaccharides on dextromethorphan-induced mood impairment and neurogenesis suppression.

Dextromethorphan (DXM) is one of the common drugs abused by adolescents. It is the active ingredient found in cough medicine which is used for suppressing cough. High dosage of DXM can induce euphoria, dissociative effects and even hallucinations. Chronic use of DXM may also lead to depressive-related symptoms. Lycium barbarum, commonly known as wolfberry, has been used as a traditional Chinese medicine for the treatment of ageing-related neurodegenerative diseases. A recent study has shown the potential beneficial effect of Lycium barbarum to reduce depression-like behavior. In the present study, we investigated the role of Lycium barbarum polysaccharide (LBP) to alleviate DXM-induced emotional distress. Sprague Dawley rats were divided into 4 groups (n=6 per group), including the normal control (vehicles only), DXM-treated group (40 mg/kg DXM), LBP-treated group (1 mg/kg LBP) and DXM+ LBP-treated group (40 mg/kg DXM and 1 mg/kg LBP). After two-week treatment, the DXM-treated group showed increased depression-like and social anxiety-like behaviors in the forced swim test and social interaction test respectively. On the other hand, the adverse behavioral effects induced by DXM were reduced by LBP treatment. Histological results showed that LBP treatment alone did not promote hippocampal neurogenesis when compared to the normal control, but LBP could lessen the suppression of hippocampal neurogenesis induced by DXM. The findings provide insights for the potential use of wolfberry as an adjunct treatment option for alleviating mood disturbances during rehabilitation of cough syrup abusers.

Involvement of central serotonergic systems in dextromethorphan-induced behavioural syndrome in rats.

Dextromethorphan, a noncompetitive blocker of the N-methyl-D-aspartate (NMDA) type of glutamate receptor, at 45, 60 and 75 mg/kg, ip doses induced a behavioural syndrome characterised by reciprocal forepaw treading, lateral head-weaving, hind-limb abduction and flat body posture. Such type of behavioural syndrome is induced by 8-hydroxy-2- (di-n-propylamino) tetralin (8-OH-DPAT) by directly stimulating the central postsynaptic 5-hydroxytryptamine (5-HT, serotonin) receptors of the 5-HT1A type. Pretreatment with buspirone (5, 10 mg/kg, ip) and l-propranolol (10, 20 mg/kg, ip) antagonised the behavioural syndrome induced by 8-OH-DPAT and dextromethorphan. Pretreatment with p-chlorophenylalanine (100 mg/kg/day x 4 days) antagonised the behavioural syndrome induced by dextromethorphan and dexfenfluramine but had no significant effect on 8-OH-DPAT induced behavioural syndrome. This indicates that dextromethorphan induces the behavioural syndrome by releasing 5-HT from serotonergic neurons with resultant activation of the postsynaptic 5-HT1A receptors by the released 5-HT. Pretreatment with fluoxetine (10 mg/kg, ip) significantly potentiated the behavioural syndrome induced by dextromethorphan and 5-hydroxytryptophan but significantly antagonised dexfenfluramine induced behavioural syndrome. This indicates that dextromethorphan releases 5-HT by a mechanism which differs from that of dexfenfluramine. Dextromethorphan may be releasing 5-HT by blocking the NMDA receptors and thereby counteracting the inhibitory influence of l-glutamate on 5-HT release.

Anticough and antimicrobial activities of Psidium guajava Linn. leaf extract.

The anticough activity of Psidium guajava Linn. (guava) leaf extract was evaluated in rats and guinea pigs. The results showed that water extract of the plant at doses of 2 and 5 g/kg, p.o. decreased the frequency of cough induced by capsaicin aerosol by 35 and 54%, respectively, as compared to the control, within 10 min after injection of the extract, (P < 0.01). However, the anticough activity is less potent than that of 3 mg/kg dextromethorphan which decreased frequency of cough by 78% (P < 0.01). An experiment on isolated rat tracheal muscle showed that the extract directly stimulated muscle contraction and also synergized with the stimulatory effect of pilocarpine. This effect was antagonized by an atropine. Moreover, growth of Staphylococcus aureus and beta-streptococcus group A, as determined by the disc diffusion method, was inhibited by water, methanol and chloroform extract of dry guava leaves (P < 0.001). The LD50 of guava leaf extract was more than 5 g/kg, p.o. These results suggest that guava leaf extract is recommended as a cough remedy.

Synthesis and some properties of two salsalate derivatives.

The synthesis of esters of 2-hydroxy benzoic acid-2-carboxyphenyl ester (salsalate) with guaiacol for the treatment of inflammatory bronchopneumopathies is reported. The antiinflammatory, analgesic and antipyretic activities of these derivatives were evaluated, together with their antioxidant, mucolytic and broncho-bacteriostatic properties in comparison to acetylsalicylic acid.

Labeling of diphenhydramine-containing drug products for over-the-counter human use. Final rule.

The Food and Drug Administration (FDA) is issuing a final rule amending the final monographs for over-the-counter (OTC) antiemetic, antihistamine, antitussive, and nighttime sleep-aid drug products to add a warning statement for oral products containing diphenhydramine citrate or diphenhydramine hydrochloride. The warning advises consumers not to use oral OTC diphenhydramine products with any other product containing diphenhydramine, including products used topically. This final rule also includes the agency's conclusions on additional warning statements and a direction statement for OTC external analgesic drug products containing diphenhydramine hydrochloride. These conclusions will be incorporated into the final monograph for OTC external analgesic drug products in a future issue of the Federal Register. FDA is issuing this final rule after considering public comments on the agency's proposed regulation and all new data and information on drug products containing diphenhydramine that have come to the agency's attention

[Clinical and experimental study on oral liquor night-cough tranquiller in treating infantile cough].

Oral Liquor of Night-Cough Tranquiller (NCT) was used in treating infantile cough and 128 patients have been treated. The result revealed that the total effective rate was 95.3%. In comparing with other group of patients treated with the common cold cough syrup and Caps. cephalexini, the latter has a clinical effective rate of 81.0%. A significant difference existed between the above-mentioned two groups (P < 0.05). According to the animal experiment, the NCT has some outstanding pharmacologic functions such as anti-tussive function, phlegm reducing and sedation, etc. While the LD50 of NCT has not been detected which indicated that this preparation has negligible side effect.

[Clinical and experimental studies of zhenkeling oral liquor on treatment infantile cough].

One hundred and seventy children with cough were divied into two groups at random. 120 patient were treated with Zhenkeling oral liquor (ZKL group). The other 50 children were given pectoral syrup (control group). The results showed that the total effective rates of ZKL group and control group were 96.7% and 56.0% respectively, and the markedly effective rates were 80.8%, 18.0% respectively (P < 0.001). Animal experiments indicated Zhenkeling has the effect of relieving cough, reducing sputum and ameliorating asthma; their antibiotic and anti-inflammatory effects were discovered too. The dosage of Zhenkeling was 100 times as clinical dose in acute toxicity test and the dosage was 32, 16, 8 times as clinical dose in long term toxicity test respectively. No adverse action was found in these experiments.

[The effect of a single therapeutic dose of Intussin on the ultrastructure of the epithelium of the respiratory tract]. / Vliv aplikace jedné terapeutické dávky Intussinu na ultrastrukturu epitelu dýchacích cest.

The effect of administration of a single therapeutic dose of Intussin on the ultrastructure of the rabbit tracheal epithelium was investigated. Twenty minutes after the application of five drops of Intussin only slight reaction of the pseudostratified ciliated epithelium was recorded. The ciliated cells manifested only slight signs of pathological alteration. Stimulation of 36 +/- 2% of goblet cells and degeneration of 7 +/- 2% of these cells were recorded. The average number of kinocilia per 1 microns2 of the ciliary border area was significantly (P less than 0.005) reduced to 6.7 +/- 0.5. However 97 +/- 2.7% of kinocilia remained intact. There was slight but significant (P less than 0.005) increase in number of pathological and degenerated kinocilia. As morphological signs of impaired mucus flow clumps and layers of inspissated secretion and numerous bacteria were found in the area of the ciliary border. Owing to the slight damage to the ciliary border and to the low degree of stimulation of the goblet cells the impairment of the self cleaning ability of the epitselium was obviously due to the ciliostatic action of some component of this preparation.

[Antitussive, expectorant and anti-asthmatic effects of Cynanchum glaucescens (Decne.) Hand. -Mazz].

The water, ethanol and ether extracts from Cynanchum glaucescems administrated orally showed significant antitussive effect in ammonia-induced cough model in mice. The water and ethanol extracts had obvious expectorant effect. The filtered solution of water decoction injected intraperitoneally could effectively prevent guinea pigs from asthma induced by acetulcholine and histamine mixture, and also inhibit the ear inflammation in mice caused by croton oil. All these effects showed close dose-effect relationship.

Characterization and pharmacodynamic properties of Arnica montana complex.

A dark brown polymeric complex was isolated from flowering parts of medicinal plant Arnica montana L. by hot alkaline extraction followed by neutralization and multi-step extractions with organic solvents. It was recovered in 5.7% yield, on GPC showed two peaks of molecular mass of 9 and 3.5kDa. The compositional analyses of Arnica complex revealed the presence of carbohydrates (26%), uronic acids (12%), phenolics (1.25mM or 213mg of GAE/1g), and low protein content (∼1%). The carbohydrate moiety was rich mainly in rhamnogalacturonan and arabinogalactan. The antitussive tests showed the reduction of the cough efforts by Arnica complex, however, its total antitussive effect was lower compared with that of codeine, the strongest antitussive agent. The bronchodilatory activity of Arnica complex was similar to salbutamol, a classic antiasthmatic drug, and was confirmed by significantly decreased values of specific airways resistance in vivo and by considerably attenuated the amplitude of acetylcholine and histamine-induced contractions in vitro. Arnica complex did not show any cytotoxic effect on mouse fibroblast cultures and human lung cells, up to the dose of 500µg/mL.

Antitussive, expectorant and bronchodilating effects of ethanol extract of Sorghum bicolor (L.) Moench roots.

ETHNOPHARMACOLOGICAL RELEVANCE: Root of Sorghum bicolor (L.) Moench (RSB) is an herbal medicine in Traditional Chinese Medicine, still used in some rural areas in Central China as an alternative remedy to treat cough and asthma. AIM OF THE STUDY: The study was aimed at evaluating the antitussive, expectorant and bronchodilating effects of ethanol extract of RSB, support its folk use with scientific evidence, and lay a foundation for its further researches. MATERIALS AND METHODS: RSB was extracted with 80% ethanol aqueous in reflux conditions, solutions were concentrated in reduced pressure, and lyophilized in vacuum to yield the RSB extract. Antitussive evaluations were carried out with three different models including ammonia liquor induced mice cough, capsaicin induced mice cough, and citric acid induced guinea pigs cough; phenol red secretion experiments in mice were performed to evaluate the expectorant ability; bronchodilating effects were evaluated with a bronchoconstrictive challenge induced by acetylcholine chloride and histamine in guinea pigs. RESULTS: In all the three antitussive tests, treatment of RSB significantly inhibited the frequency of cough, and prolonged the cough latent period in animals. And high dose of RSB (200mg/kg in mice and 100mg/kg in guinea pigs) created therapeutic activities as good as standard antitussive drug codeine phosphate (20mg/kg). In the expectorant evaluation, 50, 100 and 200mg/kg RSB treatment had significantly increased the amount of phenol red output for 0.39, 1.18, and 1.96 folds in mice tracheas. In the bronchodilating test, RSB treatment at 100mg/kg extended the preconvulsive time for 44.84% compared with that of before treatment in guinea pigs. CONCLUSIONS: RSB is an effective alternative medicine for the treatment of cough with potent antitussive, expectorant and bronchodilating activities.