Pharmaceutical and Clinical Assessment of Hydroquinone Ointment Prepared by Extemporaneous Nonsterile Compounding.

Antimelanogenic and Antioxidant Properties of Gallic Acid

“…13) However, the reported concentration of hydroquinone ointment for skin depigmentation was 5-10%. 30,31) I expect that a similar situation may exists in case of GA. Further evaluations are needed to establish GA's efficacy based on its effective dose as a potent inhibitor of melanogenesis.…”

Intradermal Concentration of Hydroquinone after Application of Hydroquinone Ointments Is Higher than Its Cytotoxic Concentration

“…9,10) p-BQ was detected at a level of 0.1-0.5% of HQ in antioxidant-free HQ ointments, but this decreased to 0-0.05% on addition of AsA and Na 2 SO 3 . 9,10) Here, it was also demonstrated that the cytotoxicity of HQ was not altered by antioxidants, AsA and Na 2 SO 3 . Consequently, it was suggested that p-BQ was not extensively cytotoxic in FR cells.…”

“…9,10) However, various problems have been observed during usage including chromatic aberration of the ointments, a relatively large variability of efficacy, and undesirable topical side effects, e.g., irritation, although they were mild. The pharmaceutical and clinical properties of HQ ointments prepared in our hospital have been evaluated, 9,10) and the following observations were made: 1) HQ ointments were highly effective in the treatment of various types of skin pigmentations; 2) Chromatic aberration occurred during 3 months of storage at room temperature, and was accelerated by exposure to high temperature, air and light; 3) Chromatic aberration was independent of the prescribed HQ content, and was not explained by alterations in the content of HQ or p-benzoquinone (p-BQ), which was formed from HQ; 4) Removal of both antioxidants resulted in the suppression of chromatic aberration; 5) Removal of Na 2 SO 3 only was further effective in suppressing chromatic aberration, and the protective effect of AsA was mainly due to its acidifying effect; 6) Chromatic aberration was due to a newly developed water-soluble material and insoluble non-covalent complex both formed by HQ and p-BQ.In this paper, to evaluate whether the topical side effects including irritation after application of the HQ ointments are due to HQ, AsA and Na 2 SO 3 , their cytotoxicity was assessed in vitro using rat skin fibroblasts as the concentration with 50% survival after 24 h exposure. 11,12) Results were compared with the intradermal concentrations after application of the HQ ointments, which were estimated by an in vitro rat skin permeation study with rat full-thickness abdominal skin and Franz-type diffusion cells.…”

Tuning the Transdermal Delivery of Hydroquinone upon Formulation with Novel Permeation Enhancers

“…The poor physicochemical stability of HQ topical formulations is a crucial problem that has led to low interest within the pharmaceutical industry for the manufacturing of HQ topical formulations; thus, patients need to rely on extemporaneously produced products prepared by community pharmacies. The chemical instability of HQ can lead to the formation of p-benzoquinone (pBQ), which is carcinogenic, and the production of other compounds that lead to dark chromatic aberrations [4,5,6]. The hydrophilic nature of HQ is an extra challenge in developing topical formulations, as its permeability is limited unless an appropriate penetration enhancer is included in the extemporaneous prepared topical products [7,8,9].…”