Post-inflammatory depigmentation following allergic contact dermatitis to chloroxylenol

Chloroxylenol

The Expert Panel for Cosmetic Ingredient Safety reviewed updated information that has become available since their original assessment from 1985, along with updated information regarding product types, and frequency and concentrations of use, and reaffirmed their original conclusion that Chloroxylenol is safe as a cosmetic ingredient in the practices of use and concentration as described in this report.

Safety of Pharmaceutical Excipients and Regulatory Issues

Background:

Pharmaceutical excipients are critical in the formulation of any dosage form. Not many additives employed in the drug product manufacture have properties, which meet the desired qualities that the finished product must have. Therefore, it is mandatory to mix the drug substance with other substances to overcome the deficiencies. As a result, almost all pharmaceutical products are mixtures of active pharmaceutical ingredient and additives. So, there is a compelling need of these substances and normally they occupy the major part of any drug product. Excipients are of different chemical categories that have varying physicochemical properties like solubility, miscibility and the nature and source of these materials vary. With growing number of pharmaceutical excipients and polymers, the question of evaluating their toxicity is becoming a complex issue. Many polymers and novel excipients are now available in the market and with their diverse chemical nature and different sources and presence of impurities and their adverse effects will further complicate the safety profiling of these excipients.

Conclusion:

This review article will discuss the unwanted biological activities of some commonly used excipients and issues of the supply of the pharmaceutical excipients that need to be highly regulated and monitored to ensure availability of quality and pure excipient compounds.

Complex mechanism of relaxation in solid chloroxylenol (antibacterial/antifungal agent) studied by ¹H NMR spectroscopy and density functional theory calculations

Molecular relaxation in antibacterial/antifungal agent: chloroxylenol (4-chloro-3,5-dimethylphenol, PCMX) in the solid state was studied by the (1)H NMR and quantum chemistry calculations. The temperature dependencies of the proton spin-lattice relaxation time (T1) in the ranges 15-273 K (at 24.667 MHz), 77-295 K (at 15 MHz), and 112-291 K at 90 MHz and the second moment (M2) of (1)H NMR resonant line in the range 106-380 K were measured. The two minima in the temperature dependence of T1 revealed two activation processes, whereas the M2 dependence in the studied range was quite flat and revealed the only significant reduction at 380 K. The low temperature part of T1(T) dependence indicated the occurrence of two processes characteristic of methyl bearing solids; the quantum mechanics governed incoherent tunneling (responsible for the low temperature flattening of T1) and the classical Arrhenius dependence governed hindered rotation (related to the wide low temperature minimum of 0.066 s at 57 K, 24.667 MHz). The 2D potential energy surface obtained using DFT/B3LYP/6-311++G(2d,p) calculations revealed the inequivalence of methyl groups and the lack of their interplay/coupling. The activation energies of classical hindered rotation are 3.35 and 2.5 kJ/mol, whereas temperatures at which the proton tunneling T(tun) finally ceases are 52 and 63 K, for inequivalent methyl groups. C(p)(T) required for the estimation of T(tun) was calculated purely theoretically on the basis of the Einstein and Debye models of specific heat and 51 modes of atomic vibrations, 4 internal rotations, and 3 torsions calculated by DFT. The -CH3 motion (tunneling and classical) results in the reduction in the (1)H NMR line second moment from 17.3 G(2) (rigid) to approximately 11.05 G(2). The pointed high temperature minimum T1(T) of 0.109 s at 89 K, 24.667 MHz, which shifts with frequency, was assigned to small-angle libration jumps, by the Θ2 = ±15° between two positions of equilibrium. The activation energy of this motion estimated on the basis of the fit of the theoretical model to the experimental points is 10.5 kJ/mol. The reduction in the (1)H NMR line second moment assigned to this motion is much lower (due to order parameter s = 0.64) and equal to 1.6 G(2). The high temperature reduction from 9.6 G(2) to 0.9 G(2) at 380 K is a result of the phase transition connected with melting (385-389 K).

Allergic contact dermatitis to chloroxylenol

Chloroxylenol, also known as p-chloro-m-xylenol (PCMX), is a compound that has been used as a preservative in cosmetics and as an active agent in antimicrobial soaps. We present two patients with allergic contact dermatitis from PCMX, confirmed by positive (+++) patch-test reactions at 48 and 72 hours, identification of PCMX in a soap and in a hand cream used by the patients, and improvement following withdrawal of the incriminating products. The mechanism of action, structure, antimicrobial activity, and dangers of PCMX are reviewed.