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PubMed1983

Hypersensitivity to procaine, tetracaine, mepivacaine, and methylparaben: report of a case.

The patient who comes for dental treatment with a history of hypersensitivity to local anesthetics is often denied the benefits of adequate pain control during dental therapy. Ninety percent of the patients challenged by Incaudo and associates were being evaluated because they needed local anesthesia for dental treatment. These same patients may some day need local anesthetic agents for minor surgery or for the treatment of cardiac arrhythmias. For those cases in which an allergic reaction is suspected, consultation with an allergist may prove beneficial to the patient by providing information and a local anesthetic that the patient can receive safely for both medical and dental needs.

Anesthesia, Dental↗
PubMed1999

Non-traditional plasticization of polymeric films.

The objective of this study was to investigate the influence of methylparaben, ibuprofen, chlorpheniramine maleate and theophylline on the thermal and mechanical properties of polymeric films of Eudragit RS 30 D. The effects of methylparaben and ibuprofen in the film coating on the rate of drug release from Eudragit RS 30 D coated beads were also studied. The physical and mechanical properties of the cast films and coated beads were investigated using thermal analysis, tensile testing, X-ray diffraction analysis and dissolution testing. The results demonstrated that the glass transition temperature of the Eudragit RS 30 D decreased with increasing levels of methylparaben, ibuprofen and chlorpheniramine maleate in the film. Theophylline exerted no influence on the thermal properties of the polymer. The higher levels of the ibuprofen and methylparaben incorporated into the film resulted in a decrease in the tensile strength of the film. The decrease in Young's modulus of Eudragit RS 30 D coated beads was attributed to an increase in the flexibility of the polymeric films when the level of methylparaben or ibuprofen in the polymeric dispersion was increased. The dissolution data demonstrated that the rate of release of the ibuprofen from coated beads was decreased by increasing the amount of ibuprofen and methylparaben in the polymeric film coating.

Chlorpheniramine↗
PubMed1990

Paraben preservatives but not succinylcholine are cerebral vasodilators in vitro.

Since the increase in intracranial pressure produced by succinylcholine is temporally associated with intravenous administration, we investigated in vitro a possible direct cerebrovascular effect of this nicotinic drug. Isometric responses were recorded from dog and guinea pig basilar artery rings suspended in modified Krebs' solution at 37 degrees C. After precontracting with a voltage (KCl)- or a receptor (5-hydroxytryptamine)-mediated agonist, cumulative concentration-relaxation curves were established for: pure succinylcholine; Quelicin from multidose vials containing 20 mg/ml succinylcholine, 1.8 mg/ml methylparaben, and 0.2 mg/ml propylparaben; Anectine from single-dose vials containing 20 mg/ml succinylcholine; multidose Anectine containing 20 mg/ml succinylcholine and 1.0 mg/ml methylparaben; and methylparaben and propylparaben alone. When required, the endothelium of dog artery was removed by gentle mechanical rubbing and the response to the drugs reevaluated. Both Quelicin and multidose Anectine produced statistically significant (P less than 0.05) relaxation; Quelicin was the more potent of the two. Methylparaben and propylparaben produced relaxation in an additive manner and completely accounted for the relaxation produced by Quelicin and multidose Anectine. The vascular relaxation was found to be independent of the presence of a functional endothelium. Consistent with a nicotinic induced contraction, pure succinylcholine maintained vessel tone. It is concluded that the pharmaceutically ubiquitous preservatives methylparaben and propylparaben but not pure succinylcholine have vasoactive properties in vitro.

Animals↗
PubMed1995

Anaphylactoid skin reactions after intravenous regional anaesthesia using 0.5% prilocaine with or without preservative--a double-blind study.

Methylparaben, the preservative of various local anaesthetic solutions, is a potential allergen. In a double-blind study, 0.5% prilocaine with (Citanest, n = 100) or without (n = 100) methylparaben were compared for the occurrence of skin reactions after intravenous regional anaesthesia of the arm in surgical patients. Skin reactions were registered after the deflation of the tourniquet cuff, and intradermal tests were performed with 0.5% prilocaine, 0.1% methylparaben and saline in all patients. Seventeen patients in the Citanest group and four patients in the methylparaben-free prilocaine group developed erythematous skin reactions in the exposed arm after deflation of the tourniquet cuff (P < 0.05, between the groups). The skin symptoms disappeared within an hour and were always restricted to the region which had been anaesthetised. None of the affected patients had positive intradermal tests. The observed skin reactions are probably non-IgE-mediated anaphylactoid reactions in which the presence of methylparaben in the local anaesthetic solution plays a major role.

Adult↗
PubMed1976

The effect of paraben preservatives on albumin binding of bilirubin.

The interaction of methylparaben and propylparaben with bilirubin-albumin complexes was studied using difference spectra, Sephadex gel filtration, red blood cell uptake of bilirubin, and the peroxidase assay. Methylparaben was found to be a weak competitor with bilirubin for binding to primary albumin-binding sites but a strong binding competitor (similar to sulfisoxazole) at secondary sites. The displacing effects of methylparaben and sulfisoxazole were additive. Propylparaben bound to albumin but did not displace bilirubin. Drugs and injectable saline and water preparations which contain methylparaben should be avoided in jaundiced newborn infants when the high-affinity albumin-binding sites approach saturation.

Benzoates↗
PubMed1985

Antibacterial properties of lidocaine on bacteria isolated from dermal lesions.

We studied the antibacterial properties of lidocaine and lidocaine with methylparaben, employing bacteria that were isolated from dermal lesions. Our study was significant because local anesthetics utilized before obtaining material for biopsy and/or culture may result in false-negative results. Killing curves were calculated to ascertain exposure times of bacteria to various concentrations of lidocaine with and without methylparaben that could affect recovery of viable bacteria from clinical specimens. The bacteria studied varied greatly in their susceptibility to lidocaine, with Neisseria species being the most sensitive. Greater inhibitory activity was noted against bacteria when methylparaben was present. Our study suggests that lower concentrations of lidocaine without methylparaben should be employed.

Bacteria↗
PubMed1981

Stability-indicating high-performance liquid chromatographic analysis of lidocaine hydrochloride and lidocaine hydrochloride with epinephrine injectable solutions.

A reversed-phase, high-performance liquid chromatographic (HPLC) procedure, which is specific and quantitative for lidocaine hydrochloride, epinephrine, and methylparaben, was developed for the analysis of lidocaine hydrochloride and lidocaine hydrochloride with epinephrine solutions for injection. Epinephrine sulfonic acid and adrenochrome are separated in this system. Also separated are lidocaine and methylparaben and their respective degradation products, 2-6-xylidine and p-hydroxybenzoic acid. The analysis requires that three detectors (two UV and one electrochemical) be connected in series. By using this arrangement, lidocaine hydrochloride and methylparaben are quantitated by UV at 254 and 280 nm, respectively, while epinephrine is quantitated electrochemically. The method is simple, accurate, precise, and rapid. No sample preparation or internal standard is necessary, and only a 2-microliter sample volume is required for analysis. Chromatographic conditions include a mu Bondapak CN column and a mobile phase of 0.01 M 1-octanesulfonic acid sodium salt, 0.1 mM edetate disodium, 2% acetic acid, 2% acetonitrile, and 1% methanol in water.

Chromatography, High Pressure Liquid↗
PubMed1994

The preservation of some oral liquid preparations. The replacement of chloroform by other preservatives.

Chloroform should be considered as an obsolete preservative for pharmaceutical preparations, because of its toxicological implications and its physical instability. The effectiveness of possible alternatives for chloroform in three oral liquid pharmaceutical preparations was investigated, using a microbiological challenge test. Magnesium trisilicate mixture (British Pharmacopoeia) can be adequately preserved with methylparaben (2 g/l). Only insignificant amounts of methylparaben were absorbed by the solids present in the magnesium trisilicate mixture. Ferrous sulfate mixture (British Pharmacopoeia) can be preserved with a mixture of methylparaben (1.8 g/l) and propylparaben (0.2 g/l). Sorbic acid (1 g/l) is a suitable preservative for promethazine hydrochloride syrup.

Administration, Oral↗
PubMed2001

Sorption of parabens by flexible tubings.

Flexible tubings are extensively used in pharmaceuticals, food industry, and in hospitals. This study was undertaken to compare various flexible tubings to determine their sorption characteristics, using methyl and propyl parabens. After 24 h, some tubings showed 100% sorption of propylparaben and over 40% for methylparaben. Significant losses were observed within a few hours using several tubings. For methylparaben, the losses were in the following decreasing order of sorption: Tygon, Clearflo, silicone, Nylotube, and Newtex. For propylparaben, the losses were in the following order: Tygon, Clearflo, silicone, Newtex, and Nylotube. Teflon, Zelite, and Vitube showed little to no losses of methyl and propylparaben over 120 h of study. The silicone tubing, refilled after 120 h with fresh methylparaben or propylparaben solutions, again showed significant losses within a few hours. The tubings show slow desorption when filled with the buffer vehicle. For Silastic tubing, increase in temperature from 25 to 40 degrees C, increase in pH from 3.5 to 6.5, tubing lot to lot variation, or curing with peroxide or platinum had little or no effect on paraben sorption. As expected, the sorption of parabens increased with increasing surface area of Silastic tubing. Results provided can be used to select the best tubings and to minimize paraben losses during production and filling of liquid pharmaceuticals andfood products containing these antimicrobial preservatives.

Adsorption↗
PubMed1989

Relationships among Cell Size, Membrane Permeability, and Preservative Resistance in Yeast Species.

The rate of uptake of propanoic acid and the cell dimensions were measured for 23 yeasts differing in their resistance to weak-acid-type preservatives. Relationships between reciprocal uptake rate, reciprocal permeability, cell volume, cell area, volume/area, and the MICs of benzoic acid and propanoic acid for the yeasts were tested by correlation analysis on pairs of parameters. The MIC of methylparaben, which is not a weak-acid-type preservative, was included. The most significant relationships found were between both reciprocal uptake rate and reciprocal permeability and the MICs of propanoic and benzoic acids Cell volume, area, and volume/area were each individually correlated with propanoic and benzoic acid MICs, but less strongly. In multiple regression analyses, inclusion of terms for volume, area, or volume/area did not markedly increase the significance. The MIC of methylparaben was unrelated to the uptake and permeability parameters, but did show a correlation with cell volume/area. Schizosaccharomyces pombe was anomalous in having very low permeability. Exclusion of these outlying data revealed particularly strong relationships (P < 0.001) between both reciprocal uptake rate and reciprocal permeability and the benzoic acid MIC. MICs for Zygosaccharomyces bailii isolates were substantially higher than for the other species, and therefore Z. baillii isolates had a large influence on the regressions. However, the relationships observed remained significant even after removal of the Z. bailii data. In showing a correlation between the rate at which propanoic acid enters yeast cells and the ability of the cells to tolerate this and other weak-acid-type preservatives, but not methylparaben, the results suggest that the resistance mechanism, in which preservative is continuously removed from the cell, is a common and major determinant of the preservative tolerance of yeast species.

Journal Article↗
PubMed2001

Hydrolysis of 4-hydroxybenzoic acid esters (parabens) and their aerobic transformation into phenol by the resistant Enterobacter cloacae strain EM.

Enterobacter cloacae strain EM was isolated from a commercial dietary mineral supplement stabilized by a mixture of methylparaben and propylparaben. It harbored a high-molecular-weight plasmid and was resistant to high concentrations of parabens. Strain EM was able to grow in liquid media containing similar amounts of parabens as found in the mineral supplement (1,700 and 180 mg of methyl and propylparaben, respectively, per liter or 11.2 and 1.0 mM) and in very high concentrations of methylparaben (3,000 mg liter(-1), or 19.7 mM). This strain was able to hydrolyze approximately 500 mg of methyl-, ethyl-, or propylparaben liter(-1) (3 mM) in less than 2 h in liquid culture, and the supernatant of a sonicated culture, after a 30-fold dilution, was able to hydrolyze 1,000 mg of methylparaben liter(-1) (6.6 mM) in 15 min. The first step of paraben degradation was the hydrolysis of the ester bond to produce 4-hydroxybenzoic acid, followed by a decarboxylation step to produce phenol under aerobic conditions. The transformation of 4-hydroxybenzoic acid into phenol was stoichiometric. The conversion of approximately 500 mg of parabens liter(-1) (3 mM) to phenol in liquid culture was completed within 5 h without significant hindrance to the growth of strain EM, while higher concentrations of parabens partially inhibited its growth.

Biodegradation, Environmental↗
PubMed2003

Development of a multidose formulation for a humanized monoclonal antibody using experimental design techniques.

The purpose of this study was to identify optimal preservatives for a multidose formulation of a humanized monoclonal antibody using experimental design techniques. The effect of antimicrobial parenteral preservatives (benzyl alcohol, chlorobutanol, methylparaben, propylparaben, phenol, and m-cresol) on protein stability was assessed using size-exclusion chromatography, differential scanning calorimetry, right-angle light scattering, UV spectroscopy, and potency testing using a cell-based fluorescence-activated cell sorting method. A quick, cost-effective preservative screening test was designed. Combinations of preservatives were examined using an I-optimal experimental design. The protein was most stable in the presence of methylparaben and propylparaben, and was compatible with benzyl alcohol and chlorobutanol at low concentrations. Phenol and m-cresol were not compatible with the protein. The I-optimal experimental design indicated that as an individual preservative, benzyl alcohol was promising. The model also indicated several effective combinations of preservatives that satisfied the antimicrobial efficacy and physical stability constraints. The preservative screening test and the experimental design approach were effective in identifying optimal concentrations of antimicrobial preservatives for a multidose protein formulation; (1) benzyl alcohol, and (2) the combination of methylparaben and chlorobutanol were screened as potential candidates to satisfy the regulatory requirements of various preservative efficacy tests.

Anti-Infective Agents↗
PubMedDate not supplied

Oestrogenic activity of isobutylparaben in vitro and in vivo.

The alkyl esters of p-hydroxybenzoic acid (parabens) are used widely as preservatives in foods, pharmaceuticals and cosmetics to which the human population is exposed. Recent studies have reported that methylparaben, ethylparaben, n-propylparaben and n-butylparaben all possess oestrogenic activity in several in vitro assays and in animal models in vivo. This study reports on the oestrogenic activity of isobutylparaben in a panel of assays in vitro and in vivo. Isobutylparaben was able to displace [(3)H]oestradiol from cytosolic oestrogen receptor alpha of MCF7 human breast cancer cells by 81% at 100 000-fold molar excess. Using a clonal line of MCF7 cells containing a stably transfected oestrogen-responsive ERE-CAT reporter gene, CAT gene expression could be increased by isobutylparaben such that the magnitude of the response was the same at 10(-5) M isobutylparaben as with 10(-8) M 17beta-oestradiol. Isobutylparaben could also increase expression of the endogenous oestrogen-responsive pS2 gene in MCF7 cells and maximal expression at 10(-5) M isobutylparaben could be inhibited with the anti-oestrogen ICI 182 780. The proliferation of two oestrogen-dependent human breast cancer cell lines MCF7 and ZR-75-1 could be increased with isobutylparaben such that at concentrations of 10(-5) M the proliferation response was of the same magnitude as with 10(-8) M 17beta-oestradiol. Evidence for oestrogen receptor mediation of proliferation effects was provided by the inability of isobutylparaben to influence the growth of oestrogen-unresponsive MDA-MB-231 human breast cancer cells and by the ability of the anti-oestrogen ICI 182 780 to inhibit the isobutylparaben effects on MCF7 cell growth. The proliferation response to 10(-10) M 17beta-oestradiol was not antagonized with isobutylparaben at any concentration from 10(-9) M to 10(-4) M in either MCF7 or ZR-75-1 cells. Finally, subcutaneous administration of isobutylparaben was able to increase the uterine weight in the immature mouse after three daily doses of 1.2 or 12.0 mg per mouse. Previous work using linear-alkyl-chain parabens has shown that oestrogenic activity increases with alkyl chain length from methylparaben to n-butylparaben. The results here show that branching of the alkyl chain to isobutylparaben increases oestrogenic activity beyond that of the equivalent length linear alkyl chain in n-butylparaben.

Animals↗
PubMedDate not supplied

Oestrogenic activity of benzylparaben.

Previous work has demonstrated that the alkyl esters of p-hydroxybenzoic acid (parabens) possess oestrogenic activity, which increases with length of alkyl chain from methylparaben to n-butylparaben and with branching in the alkyl chain from n-butylparaben to isobutylparaben. This study reports on the oestrogenic activity of benzylparaben in a variety of assays in vitro and in vivo. Benzylparaben was able to displace [(3)H]oestradiol from cytosolic oestrogen receptor (ER) of MCF7 human breast cancer cells by 22% at 1000-fold molar excess, by 40% at 10,000-fold molar excess, by 57% at 100 000-fold molar excess and by 100% at 1,000,000-fold molar excess. It was able to increase expression of a stably transfected oestrogen responsive reporter gene (ERE-CAT) in MCF7 cells after 24 h at 10(-5)M/10(-4)M and after 7 days at 10(-6)M/10(-5)M/10(-4)M. Proliferation of MCF7 cells could be increased by 10(-6)M/10(-5)M benzylparaben and this could be inhibited by 10(-7)M pure anti-oestrogen ICI 182,780, indicating that growth effects were ER mediated. Further evidence for ER-mediation was provided from the ability of benzylparaben to increase the growth of a second oestrogen-dependent human breast cancer cell line ZR-75-1, but not the oestrogen-insensitive MDA-MB-231 cell line. When tested in the presence of 10(-10)M 17beta-oestradiol, benzylparaben gave no antagonist response on the growth of either MCF7 or ZR-75-1 cells. Finally, benzylparaben could increase uterine weight in the immature mouse following topical application of three daily doses of 33 mg to dorsal skin. These results demonstrate that the oestrogenicity of methylparaben can be increased by the addition of an aryl group as well as by lengthening or branching the alkyl grouping.

Administration, Topical↗