Paraben dermatitis due to a new medicated bandage: The "paraben paradox".
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Allergens↗
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Column chromatographic analysis of barbiturates in their dosage forms. IV. Combinations with parabens.
The nature of the alkaline hydrolysis of some barbiturates in combinations with parabens (p-hydroxybenzoates) was studied with controlled variables, including temperature, viscosity, and concentrations of sodium hydroxide, barbiturate, and parabens. The kinetic studies showed that parabens could be completely hydrolyzed in strong base at 40 degrees C in 1 hr, while the barbiturate remained intact and was readily isolated by partition chromatography, Based on the theoretical results, a partition chromatographic procedure for butabarbital with parabens was devised. Standard recoveries averaged 100.7% with a standard deviation of 0.89. Kinetic data indicate that the hydrolysis of parabens could also be applied to analyze combinations with amo-, seco-, and pentobarbitals. Phenobarbital and parabens are readily separated by partition chromatographic methods without prior hydrolysis of the parabens. The low extraction constant for phenobarbital allowed its retention on a column against relatively strong solvents while the intact parabens are eluted. A slightly modified method was applied to the separation of phenobarbital from parabens. Standard recoveries average 99.9% with a standard deviation of 0.69.
Barbiturates↗
Kinetic evaluation of claimed synergistic paraben combinations using a factorial design.
The antimicrobial effects of methyl and propyl parabens are investigated, with Escherichia coli as test organism, with a view to determining whether the parabens act synergistically. At appropriate concentrations, the parabens killed E. coli cells according to first order kinetics and the bactericidal effects were quantified by the first order kill rate constants. Combinations of methyl or propyl parabens, at concentrations which slow down or inhibit bacterial growth when used singly, produced definite kill. In this sense, the parabens are therefore synergistic since in combination they produce an effect which is not observed when they are used singly. This effect is not true synergism as shown by the results of our experiments with a factorial design. Analysis of variance indicated no significant interaction between the two parabens.
Analysis of Variance↗
Routine patch testing with paraben esters.
Paraben esters are the most widely used preservatives in cosmetics and topical medicaments. Their sensitization potential is low, based on both experimental and human experience. A paraben mixture is included in the ICDRG standard series, and in patch test studies, approximately 1% of eczema patients react to it. The present study confirms this frequency in 8020 patients patch tested consecutively. Testing with the individual paraben esters was employed as confirmation, which makes it unlikely that the excited skin syndrome is a significant problem in this context. It remains undetermined whether the present paraben mixture is the optimal patch test material for diagnosing paraben sensitivity.
Female↗
Topical parabens: benefits and risks.
Parabens are the most frequently used preservative in dermatological medications. Some allergies have been reported to parabens, but these risks must be considered with respect to the benefits of parabens in concentrations used as preservatives in dermatological formulations. Considering the alternatives to parabens in preservat ives and placing perspective on the reported allergies we still find parabens to be a useful preservative with minimal risk to its benefits.
Administration, Topical↗
In vitro spermicidal activity of parabens against human spermatozoa.
Potent in vitro spermicidal activity of parabens against human spermatozoa was demonstrated in this study. The "pass" point concentration of the four parabens--methylparaben, ethylparaben, propylparaben, and butylparaben, at which all spermatozoa were immobilized and no immobilized spermatozoon revived after 30 min incubation in phosphate buffered glucose solution, was 6, 8, 3, and 1 mg/ml, respectively, as tested by Harris' method. These parabens are used as food and pharmaceutic preservatives; less toxicity and side effects were expected for the development of parabens as vaginal contraceptive agents.
Dose-Response Relationship, Drug↗
Allergic paraben and benzyl alcohol hypersensitivity relationship of the "delayed" and "immediate" varieties.
From a review of the literature, and the results of scratch, intracutaneous and subcutaneous injections of patients with parbens and benzyl alcohol sensitivity of the delayed type characterized by allergic contact dermatitis and strongly positive patch patch tests, it would appear that such sensitivity is not usually accompanied by the immediate urticarial type of allergic sensitivity. This communication concerns itself with results of testing patients with clinical sensitivity and positive patch test reactions to the parabens or benzyl alcohol with scratch, intracutaneous and subcutaneous injections of these preservatives in order to determine the relationship of the "delayed" type of allergic hypersensitivity to the parabens and benzyl alcohol with the "immediate" variety of hypersensitivity. The parabens and benzyl alcohol are widely employed as preservatives for many allergenic extracts used in scratch and intracutaneous testing. In addition, these preservatives are used in injectable corticosteroid medicaments and in local anesthetic solutions. In order to determine whether the presence of these preservatives in allergenic extracts would produce false positive scratch or intracutaneous tests or might produce an immediate, urticarial or anaphylactic reaction in patients with allergic contact dermatitis and positive patch test reactions to these preservatives, two patients with positive patch test reactions and allergic contact dermatitis to the parabens and two with similar benzyl alcohol sensitivity were tested in the manner detailed in the following case reports.
Adrenal Cortex Hormones↗
Liquid chromatographic determination of propyl paraben in cigarette filler.
A liquid chromatographic method for the quantitative determination of propyl paraben in cigarette tobacco filler has been developed. Propyl paraben is extracted from cigarette tobacco filler with acetonitrile and further purified using a silica Sep-Pak cartridge and ethyl acetate-petroleum ether (1 + 4) as eluting solvent. The purified extracts are analyzed by reverse-phase liquid chromatography using buffered water (pH 4)-acetonitrile (65 + 35) as mobile phase, with UV detection at 254 nm. Cut tobacco samples were fortified with 100 and 200 ppm propyl paraben. Average recoveries (N = 5) of propyl paraben were 98 and 94%, respectively, with coefficients of variation less than 4%.
Chromatography, Liquid↗
Thermodynamics of aqueous solutions of parabens.
The solubility of a related series of parabens was determined in water at four temperatures. The parabens chosen were the methyl through n-butyl p-hydroxybenzoates, and the temperature variations were 5 degrees increments from 25 to 40 degrees. These solutes are useful preservatives, especially combinations of the methyl and propyl ester derivatives. The chemical relationship of these compounds varied by successive linear methylene additions on the ester portion of the molecules. The thermodynamic values obtained for these aqueous systems could be related to these molecular variants since the remainder of the molecule was constant. For the overall thermodynamics, the free energy functions such as the ideal, actual, and excess were found to be smooth, nonlinear functions of the number of carbon atoms in the alkyl portion of the paraben esters. A linear relationship with the number of carbon atoms in the ester portion of these esters was found with the partial excess free energy of the solute.
Parabens↗
Relationships between the resistance of yeasts to acetic, propanoic and benzoic acids and to methyl paraben and pH.
Minimum inhibitory concentrations of acetic, propanoic and benzoic acids and methyl paraben were determined at pH 3.50 for 22 isolates of 11 yeast species, differing in their resistance to preservatives. Growth in the presence of benzoic acid enhanced the resistance of yeasts to benzoic and the other weak acid preservatives, but not to methyl paraben. Resistance to acetic, propanoic and benzoic acids was strongly correlated, but was not closely related to resistance to methyl paraben. Minimum pH for growth was not related to resistance to the weak acids. The results suggest that growth in the presence of weak-acid preservatives involves a common resistance mechanism.
Acetates↗
Parabens as antimicrobial preservatives in creams.
Antimicrobial effectiveness of methylparaben and a mixture of methyl- and propylparabens in an oil-in-water cream was studied. How the number of microbes and inclusion of nutrients into the cream affect the effectiveness of these compounds were also investigated, as well as the survival of test microbes in the cream without preservatives. Survival of microbes and antimicrobial effectiveness of parabens against the microbes in the cream were dependent on the species and number of microbes present and also on the amount of nutrients available for the microbes. In spite of the large amount of water, the cream studied did not readily support microbial growth unless the number of microbes was large or nutrients were added. Parabens were not effective antimicrobial agents against the yeast studied. The bacterial species showed different sensitivities to parabens. A mixture of methyl- and propylparabens was more effective than the methylester alone.
Bacteria↗
Rapid quantitative method for simultaneous determination of benzoic acid, sorbic acid, and four parabens in meat and nonmeat products by liquid chromatography.
A liquid chromatographic (LC) method for the simultaneous determinations of benzoic acid, sorbic acid, and methyl, ethyl, propyl, and butyl parabens (methyl, ethyl, propyl, and butyl-p-hydroxybenzoates) in meat and nonmeat products was developed. Benzoic acid, sorbic acid, and parabens were extracted from meat and nonmeat products with 70% ethanol. After filtration, extracts were analyzed by reverse phase liquid chromatography. Homogeneously ground samples of fresh sausage and hamburger were fortified with benzoic acid, sorbic acid, and each paraben at 5 different concentrations. Average recovery (after discarding outliers) for each preservative at all 5 levels was greater than 95% with a coefficient of variation less than 5%.
Animals↗
Paraben allergy.
A hydrocortisone preparation containing methylparaben and propylparaben provoked bronchospasm and pruritus when given intravenously to an asthmatic patient, whereas another hydrocortisone preparation without paraben preservative did not. Direct and passive transfer (Prausnitz-Küstner) skin tests for immediate hypersensitivity to parabens were positive. Parabens, frequently employed as bacteriostatic agents, are capable of producing immunologically mediated, immmediate systemic hypersensitivity reactions.
Asthma↗
Hypoxic radiosensitization by the antimicrobial methyl paraben.
The antimicrobial preservative, methyl paraben (methyl-4-hydroxybenzoate) sensitizes anoxic buffered suspensions of Staphylococcus aureus to gamma-radiation. The maximal response at an 0.5 mM concentration represents a 150 percent increase in response over that for deoxygenated suspensions without additive (E.R. = 2.5), and 80 percent of the response for aerated suspensions alone. Methyl paraben is not toxic to the test organism under the present test conditions.
Cobalt Radioisotopes↗
Paraben preservatives do not increase intracranial pressure in cats.
It has been hypothesized recently that succinylcholine-associated increases in intracranial pressure (ICP) are caused by the paraben preservatives contained in multidose vials. We tested that hypothesis in a standard feline model to determine the effects on ICP of equal-volume injections of preservative-free succinylcholine, succinylcholine with preservatives from multi-dose vials that contain both propylparaben and methylparaben, these preservatives alone at five times the dose contained in the succinylcholine, and normal saline. The preservatives alone increased ICP by 0.08 +/- 0.08 mmHg (+/- standard error; not significant). Normal saline had no effect on ICP. Preservative-free succinylcholine and succinylcholine with preservatives increased ICP by 4.2 +/- 0.10 and 3.8 +/- 0.07 mmHg respectively (P less than 0.01 compared to the preservatives alone and normal saline). The 99% upper confidence limit for the increase in ICP induced by the preservatives alone was 0.42 mmHg. This result suggests that parabens do not cause or substantially augment the ICP increase associated with succinylcholine administration.
Animals↗
The bactericidal activity of a methyl and propyl parabens combination: isothermal and non-isothermal studies.
The effect of temperature on the kill rate of Escherichia coli by methyl and propyl parabens was studied. The kill kinetics was first order. It was shown that the Arrhenius equation provided a good model for describing the relationship between the first order rate constant and the temperature. The activation energy was found to be 274 kJ/mol for exponential phase cells and 168 kJ/mol for stationary phase cells. Exponential phase cells were much more susceptible to the lethal effects of the parabens than were the stationary phase cells. For example, at 34 degrees C stationary phase cells, in chemically defined media, had a kill rate constant of 0.072/h while the corresponding value for exponential phase cells was 0.238/h. In water the rate of kill for exponential phase cells was even faster giving a rate constant of 5.25/h at 34 degrees C. Non-isothermal kinetic testing was not found to be useful for modelling bacterial kill kinetics because we could not achieve the precision required in bacterial enumeration.
Culture Media↗
Simultaneous quantitative determination of calcium leucovorin and parabens in lyophilized ampoules by derivative spectroscopy.
A simple and rapid procedure for quantitation of Calcium Leucovorin and parabens simultaneously in lyophilized ampoules formulation by "zero crossing" first-order derivative spectroscopy was developed. The ampoules content was dissolved in a mixture water/ethanol (50/50) and first-derivative spectra were recorded. The absolute values of the derivative at 312 nm for the determination of Calcium Leucovorin and between 244 and 246 nm for the determination of parabens were measured. The method is linear, quantitative and reproducible.
Chromatography, High Pressure Liquid↗
Contact urticaria to parabens.
Contact urticaria developed in a patient after topical application of paraben-containing compounds. Positive open patch test results and a positive passive transfer (Prausnitz-Küstner reaction) test demonstrated an immunologic mechanism for the patient's skin reaction. The importance of parabens to contact urticaria is described.
Adult↗