Bitter drugs

Freshly harvested drug (1 g) is extracted for 2h at room temperature with iOmi 70% methanol. The filtrate is evaporated to about 3 mk and 20-40 id is ii.se l for Tl.Ck 

From all stmulard eompomui 0.1% methanohe solutions are prepared ID 20 ftl i.s u.sed kcfcrcnce for FLC. i oUirk ms 

Sllha go (j0F.-,rprecOii ct] TLC plates (Merck, Germany), AtlHinlu ui 

VanilUn-siilphuric add reagent (VS No. 42) Evaluation after about 10 min at I00 C 

Visualization after about 10 min at 00°C Similar colours (vis) to those obtained with VS reagent and additional fluorescence in UV-365 nm, 

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Other drugs in combination with a sweetening agent were also studied, dextromethorphan hydrobromide [21], doxycycline hydrochloride [21], erythromycin [23], chloramphenicol [23], ampicillin [23] and cefpodoxime proxetil [23] as bitter drugs and simple syrup (2.5M sucrose solution, used as a flavoring agent prescribed by The Japanese... 

The most probable mechanism for electrical potential oscillation across the octanol membrane in the presence of a bitter drug and simple syrup is proposed as follows ... 

Buccal mucosal permeability also varies with the anatomical site for example, keratinized sites of the oral cavity hinder the permeation of hydrophilic molecules.96 Therefore, it is important to consider these factors in selecting the transmucosal route for drug delivery in the oral cavity. A limited surface area (100 to 170 cm2) and the need to mask taste for bitter drugs are some of the drawbacks associated with this route of drug delivery. 

Excipients used in the formulation usually include a mixture of a water-soluble polymer and a crystalline sugar. Mannitol and natural polysaccharides such as gelatin and alginates are used. Microencapsulation and complexation with ion exchange resins can be combined with additional flavors and sweeteners for taste masking of bitter drugs. The fairly complex nature of manufacture and scale-up contributes to... 

Although MSG is tasteless by itself, it is a flavor enhancer that can be used to improve the taste of meat, fish, fowl, vegetables, and soup. It is said to provide a unique flavor that is neither bitter, sour, sweet, or salty. Typically employed at concentrations of 0.2-0.9%, it is used extensively by the food industry in canned, frozen, and dried foods and Oriental food. It has also been used, with sugar, to improve the palatability of bitter drugs. 

Complexation with CDs can also have the effect of reducing the amount of contact with taste receptors. This can be of great benefit in the preparation of oral solutions. Not only are the drugs masked from the receptors by inclusion in the CD cavity, but the increased hydrophilicity enables the easier removal of the bitter substance from the receptor surface as well. The apparent concentration of the uncomplexed bitter drug is a function of the complexation constant. 

Sugao, H. Yamazaki, S. Shiozawa, H. Yano, K. Taste masking of bitter drug powder without loss of bioavailabihty by heat treatment of wax-coated microparticles. J. Pharm. Sci. 1998, S7 (l), 96-100. 

Bakan, J.A. Powell, T.C. Szotak, P.S. Recent advances using microencapsulation for taste-masking of bitter drugs. In Microcapsules and Nanoparticles in Medicine and Pharmacy Donbrow, M., Ed. CRC Press Boca Raton, FL, 1992 149-156. 

Water-insoluble salts may also be prepared using ion-exchange resins. Metal drug salts, in contrast to organic salts, may be problematic with respect to taste because of their alkalinity. Salts incorporating the sweet-tasting A-cyclohexylsulfamic acid (cyclamate) as the counterion can render bitter drugs such as dextromethorphan and chlorpheniramine palatable. ... 

N TABLE 41.2 Sparingly Soluble Salts or Esters of Bitter Drugs ... 

DANDELION ROOT, Taraxaci radix is the root of Taraxacum officinale, L., family Asteraceae. The drug contains bitter snb-stances like lactucopicrine (taraxacine), taraxasterol and phytosterols. Experimentally the choleretic effect in dogs and rats has been demonstrated and as a bitter drug it stimulates gastric secretion. 

Substances with a bitter taste do not constitute a chemically distinct group, and for that reason the bitter drugs are not standardised by means of a chemical method, but with an organoleptic method, i.e. determination of the bitterness value. A test panel tries to find the lowest concentration, that still has a bitter taste. An example if a bitter taste is felt with a solution of I g Gentian dissolved in 30,000 ml water, but not at a higher dilution, its bitterness value is... 

The bitter drugs also contain other substances, which is the basis for their classification into five groups. 

Quassia A bitter drug extracted from quassia wood. 

USE Flavor enhancer swine food additive with sugar, to improve palatability of bitter drugs. 

Table 39.1 Sparingly soluble salts or esters of bitter drugs...

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