Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0235290 (bitter taste)
 1,408 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A previous study investigating individuals' bitterness sensitivities found a close association among three compounds: L-tryptophan (L-trp), L-phenylalanine (L-phe) and urea (Delwiche et al., 2001, Percept. Psychophys. 63, 761-776). In the present experiment, psychophysical cross-adaptation and bitterness inhibition experiments were performed on these three compounds to determine whether the bitterness could be differentially affected by either technique. If the two experimental approaches failed to differentiate L-trp, L-phe and urea's bitterness, then we may infer they share peripheral physiological mechanisms involved in bitter taste. All compounds were intensity matched in each of 13 subjects, so the judgments of adaptation or bitterness inhibition would be based on equal initial magnitudes and, therefore, directly comparable. In the first experiment, cross-adaptation of bitterness between the amino acids was high (>80%) and reciprocal. Urea and quinine-HCl (control) did not cross-adapt with the amino acids symmetrically. In a second experiment, the sodium salts, NaCl and Na gluconate, did not differentially inhibit the bitterness of L-trp, L-phe and urea, but the control compound, MgSO(4), was differentially affected. The bitter inhibition experiment supports the hypothesis that L-trp, L-phe and urea share peripheral bitter taste mechanisms, while the adaptation experiment revealed subtle differences between urea and the amino acids indicating that urea and the amino acids activate only partially overlapping bitter taste mechanisms.
 ...
PMID:Cross-adaptation and bitterness inhibition of L-tryptophan, L-phenylalanine and urea: further support for shared peripheral physiology. 1183 10

The diverse chemical structures of stimuli that are bitter to humans suggest a need for multiple bitter receptors. Reactions of golden hamsters (Mesocricetus auratus) to 1 mM quinine hydrochloride, 3 mM denatonium benzoate, 180 mM magnesium sulfate, 30-100 mM caffeine, and 1-1.5 mM sucrose octaacetate (SOA) were studied to address whether there are multiple sensations elicited by bitter stimuli. Methods included behavioral generalization of LiCl-induced conditioned taste aversions (CTAs), intake preference tests, and electrophysiological recordings from the chorda tympani (CT) nerve. The five compounds, all bitter to humans, were all innately aversive to hamsters. CTA for the ionic quinine.HCl, denatonium benzoate, and MgSO(4) mutually cross-generalized and these ionic compounds were effective CT stimuli. Yet, the hamsters were much less sensitive to denatonium than humans, requiring a 100,000 times higher concentration for detection. CTA for nonionic caffeine and SOA did not cross-generalize to quinine or the other two ionic stimuli and these nonionic compounds were not effective CT stimuli. SOA and caffeine may elicit aversive reflexes or systemic reactions rather than taste sensations in the animals. Thus, the three ionic and two nonionic compounds form separate aversive stimulus classes in hamsters, neither of which appears to be a close homologue of the human bitter taste.
 ...
PMID:The distinctiveness of ionic and nonionic bitter stimuli. 1474 Dec 26

Based on the molecular findings that many bitter taste receptors (T2Rs) are expressed within the same receptor cells, it has been proposed that bitter taste is encoded by the activation of discrete neural elements. Here we examined how a variety of bitter stimuli are represented by neural activity in central gustatory neurons. Taste responses (spikes/s) evoked by bathing the tongue and palate with intensity-matched concentrations (in M) of 2 sugars (0.32 sucrose and 0.5 D-fructose), ethanol (40%), 4 salts (0.01 NaCl, 0.008 NaNO(3), 0.01 MgCl(2), and 0.05 KCl), 2 acids (0.003 HCl and 0.005 citric acid), and 10 bitter ligands (0.007 quinine-HCl, 0.015 denatonium benzoate, 0.003 l-cysteine, 0.001 nicotine, 0.005 strychnine-HCl, 0.04 tetraethylammonium chloride, 0.03 atropine-SO(4), 0.005 brucine-SO(4), 0.03 papaverine-HCl, and 0.009 sparteine) were recorded from 51 neurons in the nucleus of the solitary tract of anesthetized rats. Cluster analysis was used to categorize neurons into types based on responses to sucrose, NaCl, HCl, and quinine-HCl. Three groupings emerged: type S (responded optimally to sweets), type N (sodium-optimal), and type H/Q (responded robustly to bitters, acids, and salts). Multivariate analyses revealed that across-neuron patterns of response among bitter stimuli were strongly correlated. However, neural type H/Q, which was most responsive to bitter tastants, was not differentially sensitive to bitter stimuli and Na(+) salts, which rats perceive as distinct. Thus central neurons most responsive to bitter substances receive significant input from receptors that mediate other tastes, indicating that bitter stimuli are not represented by activity in specifically tuned neurons.
 ...
PMID:Neural representation of bitter taste in the nucleus of the solitary tract. 1610 27

The purpose of this research was to mask the intensely bitter taste of ondansetron HCl and to formulate a rapid-disintegrating tablet (RDT) of the taste-masked drug. Taste masking was done by complexing ondansetron HCl with aminoalkyl methacrylate copolymer (Eudragit EPO) in different ratios by the precipitation method. Drug-polymer complexes (DPCs) were tested for drug content, in vitro taste in simulated salivary fluid (SSF) of pH 6.2, and molecular property. Complex that did not release drug in SSF was considered taste-masked and selected for formulation RDTs. The complex with drug-polymer ratio of 8:2 did not show drug release in SSF; therefore, it was selected. The properties of tablets such as tensile strength, wetting time, water absorption ratio, in vitro disintegration time, and disintegration in the oral cavity were investigated to elucidate the wetting and disintegration characteristics of tablets. Polyplasdone XL-10 7% wt/wt gave the minimum disintegration time. Tablets of batch F4 containing spray-dried mannitol and microcrystalline cellulose in the ratio 1:1 and 7% wt/wt Polyplasdone XL-10 showed faster disintegration, within 12.5 seconds, than the marketed tablet (112 seconds). Good correlation between in vitro disintegration behavior and in the oral cavity was recognized. Taste evaluation of RDT in human volunteers revealed considerable taste masking with the degree of bitterness below threshold value (0.5) ultimately reaching to 0 within 15 minutes, whereas ondansetron HCl was rated intensely bitter with a score of 3 for 10 minutes. Tablets of batch F4 also revealed rapid drug release (t(90), 60 seconds) in SGF compared with marketed formulation (t(90), 240 seconds; P < .01). Thus, results conclusively demonstrated successful masking of taste and rapid disintegration of the formulated tablets in the oral cavity.
 ...
PMID:Taste masking of ondansetron hydrochloride by polymer carrier system and formulation of rapid-disintegrating tablets. 1762 21

Riboflavin-binding protein (RBP) from chicken egg, which was recently reported to be a selective sweet inhibitor for protein sweeteners, was also found to be a bitter inhibitor. RBP elicited broadly tuned inhibition of various bitter substances including quinine-HCl, naringin, theobromine, caffeine, glycyl-L-phenylalanine (Gly-Phe), and denatonium benzoate, whereas several other proteins, such as ovalbumin (OVA) and beta-lactoglobulin, were ineffective in reducing bitterness of these same compounds. Both the bitter tastes of quinine and caffeine were reduced following an oral prerinse with RBP. It was found that RBP binds to quinine but not to caffeine, theobromine, naringin, and Gly-Phe. However, the binding of RBP to quinine was probably not responsible for the bitter inhibition because OVA bound to quinine as well as RBP. Based on these results, it is suggested that the bitter inhibitory effect of RBP is the consequence of its ability to interact with taste receptors rather than because it interacts with the bitter tastants themselves. RBP may have practical uses in reducing bitterness of foods and pharmaceuticals. It may also prove a useful tool in studies of mechanisms of bitter taste.
 ...
PMID:Riboflavin-binding protein is a novel bitter inhibitor. 1784 99

Chlorhexidine (CHX) gluconate, a bitter bis-biguanide antiseptic, reduces the intensity of the salty taste of NaCl and bitter taste of quinine in humans. This study addresses regional specificity of CHX's effects on taste. Perceptual intensity and quality were measured for separate taste bud containing oral loci innervated either by afferent fibers of cranial nerve (CN) VII or CN IX. Measurements were obtained following three 1-min oral rinses with either 1.34 mM CHX or water, the control rinse. CHX rinse reduced the intensity of NaCl more at the tongue tip and palate than at posterior oral sites. Thus, fungiform and palatal salt-taste receptors may differ from salt-taste receptors of the foliate and circumvallate taste papillae. The intensity of quinine.HCl was reduced equally by CHX at all sites tested but was frequently tasteless on the less sensitive anterior sites, suggesting quinine receptor diversity. In rodents, a portion of NaCl-taste receptors in the receptive field of CN VII is sensitive to the epithelial Na+ channel blocker amiloride and a portion is amiloride insensitive; all CN IX receptors are amiloride insensitive. The current results are the first to suggest that there may also be distinct, regionally specific populations of NaCl-taste receptors in humans.
 ...
PMID:Regional specificity of chlorhexidine effects on taste perception. 1826 92

The purpose of this study was to mask the intensely bitter taste of metoclopramide HCl and to formulate a rapid disintegrating tablet (RDT) of the taste-masked drug. Taste masking was done by complexing metoclopramide HCl with aminoalkyl methacrylate copolymer (Eudragit EPO) in different ratio by the extrusion-precipitation method. Drug-polymer complexes (DPCs) were tested for drug content, in vitro taste in simulated salivary fluid (SSF) of pH 6.8, taste evaluation in oral cavity and molecular property. The complex having drug-polymer ratio of 1 : 2 shows significant taste masking, confirmed by drug release in SSF and in-vivo taste evaluation; therefore, it was selected for further study. Taste evaluation of DPCs in human volunteers revealed considerable taste masking with the degree of bitterness below threshold value (0.5) within 10 s, whereas, metoclopramide HCl was rated intensely bitter with a score of +3 for 10 s. Tablets were evaluated for various parameters like tensile strength, wetting time, water absorption ratio, in-vitro disintegration time, and disintegration in oral cavity. The effect of diluents, lubricants and sweetening agent (Xylisorb) on the disintegration time was also evaluated. Tablets of batch F3 containing mannitol and microcrystalline cellulose in the ratio 1 : 1 and 8% w/w crosspovidone showed faster disintegration (within 20 s) than the marketed formulation (180 s). Good correlation between in vitro disintegration behavior and in the oral cavity was recognized. Tablets of batch F3 also revealed rapid drug release (t(90), 90 s) in SGF compared with marketed formulation (t(90), 600 s).
 ...
PMID:Rapidly disintegrating tablets containing taste masked metoclopramide hydrochloride prepared by extrusion-precipitation method. 2041 Jun 20

An attempt was made to sustain the release of metformin HCl as well as to mask the bitter taste by complexation technique using strong cation-exchange resins, indion 244 and indion 264. The drug loading onto ion-exchange resin was optimized for mixing time, activation, effect of pH, mode of mixing, ratio of drug:resin and temperature. The resinate was evaluated for micromeritic properties, taste masking and characterized using XRPD and IR. Using resinate sustained release tablets were formulated using hydoxypropylmethylcellulose K100M.The tablets were evaluated for hardness, thickness, friability, drug content, weight variation and in vitro drug release. Tablets thus formulated (Batch B-6) provided sustained release of drug over a period of 10 h with first order kinetics. The release of metformin HCl from resinate controls the diffusion of drug molecules through the polymeric material into aqueous medium. Results showed that metformin HCl was successfully taste masked and formulated into a sustained dosage form as an alternative to the conventional tablet.
 ...
PMID:Formulation and In vitro Evaluation of Sustained Release Dosage Form with Taste Masking of Metformin Hydrochloride. 2083 21

Ondansetron hydrochloride is an intensely bitter antiemetic drug used to treat nausea and vomiting following chemotherapy. The purpose of the present work was to mask the taste of ondansetron hydrochloride and to formulate its patient-friendly dosage form. Complexation technique using indion 234 (polycyclic potassium with carboxylic functionality) and an ion-exchange resin was used to mask the bitter taste and then the taste-masked drug was formulated into an orodispersible tablet (ODT). The drug loading onto the ion-exchange resin was optimized for mixing time, activation, effect of pH, mode of mixing, ratio of drug to resin and temperature. The resinate was evaluated for taste masking and characterized by X-ray diffraction study and infrared spectroscopy. ODTs were formulated using the drug-resin complex. The developed tablets were evaluated for hardness, friability, drug content, weight variation, content uniformity, friability, water absorption ratio, in vitro and in vivo disintegration time and in vitro drug release. The tablets disintegrated in vitro and in vivo within 24 and 27 s, respectively. Drug release from the tablet was completed within 2 min. The obtained results revealed that ondansetron HCl has been successfully taste masked and formulated into an ODT as a suitable alternative to the conventional tablets.
 ...
PMID:Formulation and characterization of patient-friendly dosage form of ondansetron hydrochloride. 2104 78

The aim of this investigation was to evaluate the complexation potential of brompheniramine maleate (BPM) and tannic acid (TA) for sustained release and taste masking effects. The complexes (1:1-1:7 TA to BPM ratio) were prepared by the solvent evaporation method using methanol, phosphate buffer pH 6.8 or 0.1N HCl as common solvents. The complexes were characterized microscopically by scanning electron microscopy (SEM), chemically by Fourier transform infrared (FTIR) and solid-state NMR (SSNMR), thermally by differential scanning calorimetry (DSC), for crystallinity by powder X-ray powder diffraction (PXRD), for organoleptic evaluation by electronic tongue (e-tongue), and for solubility in 0.1N HCl and phosphate buffer pH 6.8. The dissolution studies were carried out using the USP II method at 50 rpm in 500 ml of dissolution media (0.1N HCl or phosphate buffer pH 6.8). SEM images revealed that the morphology of complexes were completely different from the individual components, and all complexes had the same morphological characteristics, irrespective of the solvent used for their preparation, pH or ratio of BPM and TA. The FTIR spectra showed the presence of chemical interactions between the TA and BPM. DSC, PXRD and SSNMR indicated that the drug lost its crystalline nature by formation of the complex. Complexation has significantly reduced the solubility of BPM and sustained the drug release up to 24h in phosphate buffer pH 6.8 media. The bitter taste of the BPM was completely masked which was indicated by Euclidean distance values which was far from the drug but near to its placebo in the complexes in all ratios studied. The taste masked complexes can be potentially developed as suitable dosage forms for pediatric use. In summary, complexation of BPM and TA effectively sustained the dissolution and masked the bitter taste of drug for the development of suitable dosage forms for pediatric use.
 ...
PMID:Tannate complexes of antihistaminic drug: sustained release and taste masking approaches. 2203 47


<< Previous 1 2 3 4 Next >>