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.

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.

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.

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.

Toxicokinetics of naringin, a putative antitussive, after 184-day repeated oral administration in rats

The toxicokinetic characteristics of naringin were investigated in rats that had been orally administered naringin extract, a candidate for oral treatment of cough, prepared from Citrus grandis "Tomentosa", at 50, 250, or 1250 mg/kg/day in a repeated-dose study for 1, 32, 93, or 184 days. Increased values of the mean systemic exposure were approximately proportional to increases in dose levels during all collection intervals; no saturation was observed. No significant differences in mean systemic exposure were observed between male and female rats. Results provide a reference for interpretation of toxicology findings and relevance to clinical safety issues.

Intoxication with over-the-counter antitussive medication containing dihydrocodeine and chlorpheniramine causes generalized convulsion and mixed acidosis

We report a 35-year-old man who was referred to our hospital with generalized convulsion and mixed acidosis presumably caused by abuse of SS-BRON tablets, an over-the-counter (OTC) antitussive medication sold in Japan. These tablets contain dihydrocodeine phosphate, methylephedrine, chlorpheniramine, and caffeine. Although it is difficult to discern which component caused these symptoms, it seems that dihydrocodeine phosphate or methylephedrine was involved in the addiction to SS-BRON and chlorpheniramine may have caused the generalized convulsion. It should be recognized that an OTC antitussive, which is quite easy to obtain, can be abused and subsequently induce serious intoxication.

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.

In Vitro Metabolism of Isoline, a Pyrrolizidine Alkaloid fromLigularia duciformis, by Rodent Liver Microsomal Esterase and Enhanced Hepatotoxicity by Esterase Inhibitors

Isoline, a major retronecine-type pyrrolizidine alkaloid (PA) from the Chinese medicinal herb Ligularia duciformis, was suggested to be the most toxic known PA. Its in vitro metabolism was thus examined in rat and mouse liver microsomes, and its toxicity was compared with that of clivorine and monocrotaline after i.p. injection in mice. Isoline was more rapidly metabolized by both microsomes than clivorine and monocrotaline and converted to two polar metabolites M1 and M2, which were spectroscopically determined to be bisline (a deacetylated metabolite of isoline) and bisline lactone, respectively. Both metabolites were formed in the presence or absence of an NADPH-generating system with liver microsomes but not cytosol. Their formation was completely inhibited by the esterase inhibitors, triorthocresyl phosphate (TOCP) and phenylmethylsulfonyl fluoride, but not at all or partially by cytochrome P450 (P450) inhibitors, alpha-naphthoflavone and proadifen (SKF 525A), respectively. These results demonstrated that both metabolites were produced by microsomal esterase(s) but not P450 isozymes. The esterase(s) involved showed not only quite different activities but also responses to different inhibitors in rat and mouse liver microsomes, suggesting that different key isozyme(s) or combinations might be responsible for the deacetylation of isoline. Isoline injected i.p. into mice induced liver-specific toxicity that was much greater than that with either clivorine or monocrotaline, as judged by histopathology as well as serum alanine aminotransferase and aspartate aminotransferase levels. Isoline-induced hepatotoxicity was remarkably enhanced by the esterase inhibitor TOCP but was reduced by the P450 inhibitor SKF 525A, indicating that rodent hepatic esterase(s) played a principal role in the detoxification of isoline via rapid deacetylation in vivo.

Dextromethorphan psychosis, dependence and physical withdrawal

As part of a synthesis of evidence regarding the abuse and addiction liability of dextromethorphan (DM), an over-the-counter cough medicine available in over 140 preparations, an uncommonly published case of dextromethorphan dependence (addiction) is described, with specific, rarely published complications. The individual was interviewed and several medical databases were also reviewed (Medline, 1966-present; PubMed) for all content relating to the Keywords: dextromethorphan, abuse, dependence, cough medicine, addiction, withdrawal, psychosis. The patient evidenced history suggesting substance dependence, substance-induced psychosis and substance withdrawal in relation to DM. A literature review revealed that DM has specific serotonergic and sigma-1 opioidergic properties. Dextrorphan (DOR), the active metabolite of DM, has similar properties; however, DOR is a weaker sigma opioid receptor agonist, and a stronger NMDA receptor antagonist. DM and DOR display specific biological features of addiction, and are capable of inducing specific psychiatric sequelae. A specific, reproducible toxidrome with significant psychiatric effects occurred, when DM was abused at greater than indicated doses, with more profound and potentially life-threatening effects at even higher doses. DM withdrawal appears evident. DM's active metabolite, DOR, has pharmacodynamic properties and intoxication effects similar to dissociatives, and may be more responsible for the dissociative effect that this DM abuser sought. However, it is this same metabolite that may be fraught with the potentially life-threatening psychoses and dissociative-induced accidents, as well as addiction. While DM has been hypothesized as the most commonly abused dissociative, health-care providers seem largely unaware of its toxidrome and addiction liability.

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.

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

Noscapine inhibits tumor growth with little toxicity to normal tissues or inhibition of immune responses

Noscapine, a phthalideisoquinoline alkaloid derived from opium, has been used as an oral anti-tussive agent and has shown very few toxic effects in animals or humans. Recently, we reported that noscapine binds stoichiometrically to tubulin and promotes microtubule polymerization. Noscapine causes growth arrest of tumor cells in mitosis and induces apoptosis of tumor cells in vitro. Previous experiments also showed that noscapine has potent antitumor activity in mice when administered parenterally or by gastric lavage. Here, we report that the anti-mitotic effect was specific to noscapine since closely related compounds did not inhibit the growth of a lymphoma cell line. In addition, noscapine was shown to be effective in reducing the growth of the lymphoma and increasing the survival of tumor-bearing mice when administered in the drinking water. It is noteworthy that, noscapine showed little or no toxicity to kidney, liver, heart, bone marrow, spleen or small intestine at tumor-suppressive doses. Furthermore, oral noscapine did not inhibit primary immune responses, which are critically dependent upon proliferation of lymphoid cells. Thus, our results indicate that noscapine has the potential to be an effective chemotherapeutic agent for the treatment of human cancer.

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.

Comparative toxicology of two enantiomers of the peripherally acting non-narcotic antitussive drug moguisteine

Moguisteine (R,S(+/-)-2-(2-methoxyphenoxy)-methyl-3-ethoxycarbonylacetyl-1,3-t hiazolidine, CAS 119637-67-1), a new peripheral non-narcotic antitussive drug, is a racemate composed of an equimolar mixture of R(+) and S(-) enantiomers (BBR 2221 and BBR 2222, respectively). Since in some cases the use of only one enantiomer instead of a racemate may increase the efficacy and/or the tolerability of a compound, moguisteine enantiomers were submitted to toxicological evaluation. Given in a single oral (gavage) or intraperitoneal administration to mice and rats, both moguisteine enantiomers show very low general toxicity. Administered by gavage to rats and dogs for four consecutive weeks, BBR 221 and BBR 2222 are tolerated at up to the dose of 240 mg/kg/day in both sexes with no appreciable toxic changes. Finally, the mutagenicity tests show that both enantiomers are devoid of any mutagenic potential both in vitro and in vivo. Considering the overall results of the toxicological studies and comparing them with the data obtained from the previously performed studies with the racemate moguisteine, it can be affirmed that no differences can be identified between the two enantiomers and the racemate moguisteine. These findings justify the development of moguisteine as a racemate since neither enantiomer should offer any advantage over the racemate.

[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.

Pharmacological profile of dextrorphan

Dextrorphan (CAS 125-73-5) is the active metabolite of the antitussive agent dextromethorphan (CAS 125-71-3). The activity of dextromethorphan, its specific pharmacology, acute toxicity and general pharmacology in respect to the central nervous system were investigated in comparison to dextromethorphan. The studies showed that dextrorphan exerts an antitussive activity comparable to the one of dextromethorphan, but a better tolerability and a lower toxicity. These results suggest to use dextrorphan instead of its precursor dextromethorphan in therapy.

[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.

[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.

Reproductive toxicology of the new antitussive moguisteine

Moguisteine (R,S(+/-)-2-(2-methoxyphenoxy)-methyl-3-ethoxycarbonylacetyl- 1,3-thiazolidine, CAS 119637-67-1), a new oral non narcotic peripherally acting antitussive drug, was examined for effects in the rat on general reproductive performance (at 0, 50, 212, 900 mg/kg/d,) for embryotoxicity (at 0, 25, 75, 225, 900 mg/kg/d) and for peri-postnatal toxicity (at 0, 62.5, 250, 1000 mg/kg/d). Embryotoxicity (at 0, 75, 225, 900 mg/kg/d) was also examined in the New Zealand White rabbit. In all the studies, moguisteine was administered orally as a suspension by gavage. At the tested doses, moguisteine did not interfere with general reproductive performance, either in the F0 or in the F1 generation. The drug did not show any toxic effect on the dams and their fetuses, nor did it have any teratogenic effect in either of the tested species. Finally, moguisteine had no adverse effects, either on parturition or on peri-and postnatal survival and/or development of the offspring.

General toxicology of the new antitussive moguisteine

Moguisteine (R,S(+/-)-2-(2-methoxyphenoxy)-methyl-3-ethoxycarbonylacetyl- 1,3-thiazolidine, CAS 119637-67-1), a new oral non-narcotic peripherally acting antitussive drug, was submitted to toxicological evaluation. The oral (gavage) and intraperitoneal routes in mice and rats and the oral route in rabbits produce very low acute toxicity. Administered by oral route, moguisteine proved to be well tolerated for 26 consecutive weeks and did not induce any general or local effect at up to the respective doses of 240 and 60 mg/kg/day for rats and dogs. In oral (dietary) carcinogenicity studies, moguisteine did not exhibit any carcinogenic effect in mice and rats treated for 87 and 104 weeks, respectively, at up to the dose of 600 mg/kg/day. These results are supported by the absence, both in vitro and in vivo, of mutagenic potential. Considering the overall results of the toxicological studies, it can be affirmed that moguisteine enjoys reliable tolerability, as also shown by a wide safety margin calculated on the basis of the animal and human exposures.

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.

Safety and toxicological profile of the new antitussive levodropropizine

Levodropropizine (S(-)-3-(4-phenyl-piperazin-1-yl)-propane-1,2-diol, DF 526), a new antitussive drug, was submitted to toxicological studies. Acute toxicity, both oral and intraperitoneal, in rats and mice and oral toxicity in guinea-pigs was low. Subchronic and chronic toxicity studies were performed in rats and dogs. For both species the maximum tolerated oral dosage was 24 mg/kg/d. Dose-related clinical signs were observed, consisting mainly in salivation in rats and sedation, peripheral vasodilatation and increased heart rate in dogs. Liver toxicity was found in both species at higher dosages. In rats, food intake and body weight gain were reduced. There were no effects on fertility, nor any teratogenic effects. Foetal and peri- and post-natal toxic effects were observed in rats only at 150 mg/kg/d. A set of mutagenicity tests yielded negative results. Therefore, levodropropizine is safe up to dosages 10 times greater than the one intended for clinical use and only slight adverse reactions were recorded at a dosage 30 times greater.

Comparison of the effects of two opioid antitussives, vadocaine hydrochloride, clobutinol and lidocaine on lung mechanics in guinea-pigs

Intravenous administration of opioids, e.g. morphine and codeine, causes bronchoconstriction in animals and susceptible patients such as asthmatics. Therefore, the effects of two opioid antitussives (codeine and dextromethorphan), two non-opioid antitussives (vadocaine hydrochloride (2',4'-dimethyl-6'-methoxy-3-(2-methylpiperidyl) propionanilide hydrochloride, OR K-242-HCl; INN: vadocaine) and clobutinol), and lidocaine on basal lung mechanics and methacholine (MeCh, 6 micrograms/kg i.v.)-induced airway obstruction were investigated in anaesthetized guinea-pigs. Intravenous administration of codeine (10-20 mg/kg) produced a dual response in the airways; initial bronchoconstriction was followed by attenuation of the MeCh-response. Dextromethorphan (10 and 15 mg/kg) caused bronchoconstriction only. Both the opioids affected dynamic lung compliance (CDyn) more than lung resistance (RL). At doses between 1 and 20 mg/kg i.v., vadocaine, clobutinol, and lidocaine had no obvious effect on the airways. Dextromethorphan and vadocaine, both at doses of 10 and 15 mg/kg, and clobutinol (15 and 20 mg/kg) caused irreversible bradycardia and hypotension, whereas codeine (5-20 mg/kg) increased blood pressure, and to a lesser extent heart rate. These results suggest that intravenous administration of an opioid antitussive influences the small peripheral airways more than the large airways, whether the opioid has euphoric analgesic properties or not. In contrast to this, non-opioid antitussives such as vadocaine and clobutinol are without effect. At large doses, all antitussives influence the cardiovascular system considerably.

[Toxicological characteristics of the antitussive preparation glaucine]

A toxicological study was made of the antitussive drug glaucinee hydrochloride, an alkaloid of the isoquinoline series (4,5,7,8-tetramethoxyaporphine hydrochloride) isolated from Glaucinum flavum Crantz. of the Papaveraceae family. Upon a single intraperitoneal injection to different laboratory animals the LD50 was found to be equal to 150--180 mg/kg whereas upon intragastric administration, to 510--620 mg/kg. Under the conditions of chronic experiments (intragastric administration to rats in doses of 5, 25 adn 75 mg/kg daily for 3 months) glaucin hydrochloride did not affect the general status of the animals, hematological characteristics, functions of the liver, cardiovascular and excretory systems, and the morphological indicators of the internal organs as shown by electron microscopy. The drug does not possess any allergizing, mutagenic, embryotoxic or teratogenic properties. The data obtained attest to the possibilities of a wide clinical application of glaucin hydrochloride as an antitussive drug.

General pharmacological properties of a new non-opiate antitussive: zipeprol (3024 CERM). I. Action on respiratory function and acute toxicity

1-(2-Methoxy-2-phenyl)-ethyl-4-(2-hydroxy-3-methoxy-3-phenyl)-propyl-iperazine-dihydrochloride (zipeprol, Respilene) is a substance of non-phenanthrenic chemical structure. In the cat, it antagonised cough induced by stimulation of the superior laryngeal nerve or by direct mechanical excitation of the sensitive tracheo-bronchial receptors. The efficacy of zipeprol after enteral administration made it possible both to establish good intestinal absorption and to rank it favourably in relation to several major antitussive reference products; codeine, codethyline, dextromethorphan, diphenhydramine and pentoxyverine. The activity of zipeprol was superior or equal to that of all these substances, excdept codeine. The antitussive properties appeared to be due to a central action. Other properties have been demonstrated which suggest at least a supplementary mechanism in the inhibition of cough, in addition to the central action. These consisted of slight antihistamine and anticholinergic properties, marked local-anesthetic potency and bronchospasmolytic activity. This latter property was demonstrated by the inhibition of histamine and serotonin induced bronchospasm in the guinea-pig. In vitro, using human sputum, zipeprol had a mucolytic action, shown by a decrease in sputum vis viscosity and lysis of DNA and AMPS fibrils. In the dog, at high doses, zipeprol unlike codeine, did not inhibit central stimulation of respiration by hypercapnia, in addition no modification of ventilatory dynamics or blood gases was seen. On the basis of these results, zipeprol can be considered as possessing no respiratory depressant effect even in the upper ranges of its antitussive doses.

[Pharmacological studies of a new antitussive, 1-phenethyl-4-hydroxy-salicylamido-4-methyl-piperidine-hydrochloride (S 1592) (author's transl)]

1-Phenethyl-4-hydroxy-salicylamido-4-methylpiperidine-hydrochloride (S 1592) markedly inhibits coughing induced in laboratory animals by chemical or mechanical irritation of respiratory tract or by electrical stimulation of the superior laryngeal nerve. The drug has low acute toxicity in mice and rats. The new compound possesses bronchodilating and antianaphylactic properties and does not affect gastrointestinal propulsion. Cardiovascular effects are absent.

Dextromethorphan-monoamine oxidase inhibitor interaction in rabbits

Severe toxic reactions may occur clinically when imipramine, pethidine or dextromethorphan is administered to a patient being treated with a monoamine oxidase inhibitor (MAOI). Previous reports indicate that imipramine or pethidine produces symptoms characterized by motor restlessness, tremor, extreme hyperpyrexia and death when administered to phenelzine-pretreated rabbits. The present study shows that dextromethorphan (5 mg kg−1) produces identical symptoms in rabbits pretreated with phenelzine sulphate (30 mg kg−1) or nialamide HCl (50 mg kg−1) 42 and 18 h before temperature recording. The dextromethorphan-MAOI interaction appears to be due to a 5-hydroxytryptamine potentiation. In the unanaesthetized cat nictitating membrane preparation, dextromethorphan (5 mg kg−1) markedly enhanced the response of noradrenaline and 5-HT but antagonized the effects of tyramine. This suggests that dextromethorphan blocks the uptake of these amines in the adrenergic nerve endings.

Pharmacological studies of a new antitussive, 4-phenyl-l-piperidinecarboxamide (AH 1932)

4-Phenyl-1-piperidinecarboxamide (AH 1932) markedly inhibits coughing induced in laboratory animals by chemical or mechanical irritation of the respiratory tract or by electrical stimulation of the superior laryngeal nerve. The compound is effective administered orally or parenterally and is at least as active as codeine. In contrast to codeine the antitussive activity of AH 1932 persists for 6 hr after oral administration. The evidence suggests a central site of action for AH 1932. The drug has a low acute toxicity in mice and rats, is devoid of analgesic activity, has no effect on the respiratory system and does not affect gastrointestinal propulsion. Cardiovascular effects are minimal. AH 1932 possesses weak spinal interneuron blocking activity unlikely to limit its use as a cough suppressant.