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Biomedical subjects

L Chafetz

Publications and source records attributed to L Chafetz.

15 recordsLinked to original sources
PubMed1991

Stability of diltiazem in acid solution.

A brief study of the stability of diltiazem was conducted at 70 degrees C in the pH range of 0.45 to 6.1 using polarimetry. Racemization did not occur. The hydrolysis rate of the acetate ester moiety was found to be slow, with a minimum in the pH-rate catenary at approximately pH 3.5. Where reaction products are known, photoelectric polarimetry has great advantages in speed, convenience, and cost compared with chromatographic methods for measuring rates of reaction of optically active analytes.

Diltiazem↗
PubMed1989

Issues in psychiatric caregiving.

This report presents descriptive data from a pilot investigation of 20 family caregivers to the psychiatrically disabled. Data were obtained through focused interviews with caregivers recruited from community organizations and clinical services. The model subject was a middle-aged mother caring for an adult child with schizophrenia. Qualitative analysis of interview data identified major concerns and support needs of individuals who assume this stressful role. Mental health nurses may assist caregivers to obtain support, reduce risks to their own well-being, and to promote well-being of the mentally ill.

Adult↗
PubMed1987

Phenolic cyclization of epinephrine, metaproterenol, metaraminol, phenylephrine, and terbutaline with formaldehyde.

An exploratory study of the rates of cyclization of the title compounds, all 3-hydroxyphenalkanolamines, with formaldehyde to 1,2,3,4-tetrahydroisoquinolines (THIQs) was performed using high-performance liquid chromatographic (HPLC) methods. Reactions occur quantitatively and practically instantaneously at room temperature and neutral pH; thus, rates were measured at acid pH. Cyclization occurs ortho or para to the 3-phenolic function, so that all but the 3,5-dihydroxyphenyl derivatives, metaproterenol and terbutaline, gave two THIQs. Terbutaline reacted significantly slower than the other compounds. Formaldehyde occurs in pharmaceutical systems and it serves as a model for other aldehydes that occur in sugars and flavors. The pharmaceutical implications of the reaction are discussed.

Cyclization↗
PubMed1977

IR spectrophotometric assay of carbachol solutions.

Carbachol ophthalmic solutions can be assayed by evaporating a measured volume, dissolving the residue in methanol, and scanning the carbonyl stretching frequency in an IR spectrophotometer using a cell with calcium fluoride windows. Methylcellulose and other formulation vehicle components do not interfere. The method is stability indicating with respect to hydrolysis. It affords a recovery of 99.5+/-0.51% (RSD).

Carbachol↗
PubMed1977

Selective photometric determination of betamethasone benzoate and other 21-hydroxycorticosteroids.

Condensation of the glyoxal obtained by cupric acetate oxidation of 21-hydroxycorticosteroids with acetous phenylhydrazine reagent affords a near UV chromophore. All of the tested corticosteroids, including triamicinolone acetonide, which gives low color yields in the Porter-Silber reaction and its Lewbart-Mattox modification, gave similar absorption maxima (362-370 nm) and molar absorptivities (epsilon = 17,000-20,500). Since corticosteroid 21-esters and oxidation products do not undergo the reaction, the assay method based on it is stability indicating for betamethasone benzoate and the other test compounds. Procedures are described for the assay of two topical betamethasone benzoate preparations and hydrocortisone and prednisolone tablets; recovery and precision data are given.

Betamethasone↗
PubMed1976

Stabilized compressed nitroglycerin tablets.

A stabilized compressed nitroglycerin tablet, containing microocrystalline cellulose NF and providone NF as stabilizing agents, was formulated. Bioavailability and physical tests were conducted on the compressed tablet and two leading brands of molded tablets. There was no difference in the mean pulse rate between a molded tablet formulation and the compressed tablet in a crossover study using 10 human volunteers and three tablet strengths, 0.3, 0.4, and 0.6 mg. The compressed tablet was most uniform when tested according to the USP method for weight variation and content uniformity. Various tests for nitroglycerin loss due to volatility, i.e., open dish test, thermogravimetric analysis, and simulated in-use test, all indicated that the stabilized compressed tablet was substantially more stable than partially stabilized or unstabilized molded tablets.

Adult↗
PubMed1976

Dissolution testing of nitroglycerin tablets.

The available types of dissolution testing apparatus for tablets and capsules are inapplicable to sublingual tablets, since these tablets are formulated to release their drug content within minutes in a small volume of fluid. A simple dissolution test method was developed for nitroglycerin tablets based on the reduction of nitroglycerin at a rotating platinum electrode, which provides reproducible stirring. The system provides instantaneous and continuous measurement of dissolved nitroglycerin in a small constant volume of buffered isotonic sodium chloride solution over a period of seconds to several minutes, when reduction is complete as shown by the current-time curve. Since the height of the curve is directly proportional to the amount of nitroglycerin in solution, the method also can be used to determine the drug content of individual tablets.

Chemistry, Pharmaceutical↗
PubMed1975

Selective assay of benzoyl peroxide in lotions and creams.

A selective titrimetric method for the determination of benzoyl peroxide in lotions and creams was developed. It is based on the work of Horner and Jürgens, in which diacylperoxides, dialkylperoxides, peracids, and alkylhydroperoxides can be determined selectively by iodometry and acidimetry. The proposed assay is stability indicating with respect to peracids. Good recovery data were obtained.

Benzoyl Peroxide↗