Renova Retin-A
Densitometric thin layer chromatographic analysis of tretinoin and erythromycin in lotions for topical use in acne treatment.

Gabriels M, Brisaert M, Plaizier-Vercammen J.

Pharmaceutical Institute, Vrije Universiteit Brussel, Brussels, Belgium.

A TLC-method was developed to analyse tretinoin and erythromycin in a lotion in the presence of several excipients. Erythromycin was separated on a silica gel plate and a mobile phase with dichloromethane, methanol and ammonia 25% (60:6:1 (v/v/v)), tretinoin on a C(18) RP plate with acetonitrile and water (50:25 (v/v)) as mobile phase, adding 1 ml acetic acid for the separation of the excipients and erythromycin. The derivatization for both was done with a dipping reagent, consisting of anisaldehyde, sulphuric acid and acetic acid (respectively 1, 2 and 10% (v/v/v)) and dissolved in chloroform/alcohol 94% v/v (60:30 (v/v)) for erythromycin and alcohol 94%/water (50:40 (v/v)) for tretinoin. These TLC-systems were quantitatively evaluated in terms of stability of the colour, precision, accuracy and calibration, proving the utility in the analysis of the lotion.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10477329&dopt=Abstract tretinoin Retin-A Renova



Renova Retin-A
Immunomodulatory effects of tretinoin in combination with clindamycin.

Wauben-Penris PJ, Cerneus DP, van den Hoven WE, Leuven PJ, den Brok JH, Hall DW.

Yamanouchi Europe B.V. Research Laboratories, Leiderdorp, The Netherlands. wauben.nl yamanouchi-eu.com

BACKGROUND: Since acne is a multifactorial skin disease, therapies affecting several etiologic factors can have a higher than expected effectiveness. A combination of the antibiotic clindamycin phosphate and the retinoic acid tretinoin was developed. OBJECTIVE: Anti-inflammatory and immunomodulatory effects of tretinoin in vitro were studied on human keratinocytes and peripheral blood mononuclear cells (PBMCs). Effects of clindamycin phosphate on tretinoin effects were studied. METHODS: Anti-inflammatory effects on keratinocytes were assessed using an in vitro model with PMA (phorbol ester)-stimulated A431 cells (human epidermoid carcinoma). Immunomodulatory effects were measured on superantigen (SEB) stimulated PBMCs. RESULTS: Tretinoin showed very potent inhibition of PMA-stimulated IL-6 (interleukin 6) release by A431 cells. The addition of clindamycin phosphate did not interfere with this effect. Tretinoin very potently stimulated IL-5 release, and inhibited IFN gamma release by SEB-stimulated human PBMCs. This indicates an immunomodulatory effect, stimulating Th2, and inhibiting Th1 dominated responses. These features have been related to the healing of acne lesions. The addition of clindamycin phosphate did not interfere with the immunomodulatory effects of tretinoin. CONCLUSION: The combination of tretinoin and clindamycin phosphate can be expected to be very effective in acne therapy.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9891902&dopt=Abstract tretinoin Retin-A Renova



Renova Retin-A
Clinical efficacy of Velac, a new tretinoin and clindamycin phosphate gel in acne vulgaris.

Cambazard F.

C.H.U. de Saint Etienne, Department of Dermatology, France.

Velac, a new gel formulation containing both tretinoin (0.025%) and clindamycin phosphate (1.2%), is effective in acne vulgaris using a once daily application. The single formulation enhances compliance in young patients and improves the therapeutic results. Treatment with Velac was found to be more effective than tretinoin alone in inflamed lesions and at least comparable in open and closed comedones. In two of the three studies the overall acne severity grade was significantly more reduced when compared with tretinoin. Velac is also more effective than clindamycin alone in the treatment of the non-inflamed lesions. In the two multicentre studies the reduction of the overall acne severity grade was also more favourable for the new gel formulation. A more rapid response occurred with Velac than with either component used (clindamycin or tretinoin) alone.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9891905&dopt=Abstract tretinoin Retin-A Renova



Renova Retin-A
Chemical stability of adapalene and tretinoin when combined with benzoyl peroxide in presence and in absence of visible light and ultraviolet radiation.

Martin B, Meunier C, Montels D, Watts O.

Galderma R & D, Valbonne, France.

Adapalene and tretinoin are molecules used in the topical treatment of acne vulgaris. Commercial formulations (adapalene 0.1% gel and tretinoin 0.025% gel) were mixed with equal volumes of commercially available benzoyl peroxide formulation (10% lotion) and subsequently exposed to light over 24 h. With and without exposition to light, adapalene exhibits a remarkable stability whereas tretinoin is very sensitive to light and oxidation. The combination of benzoyl peroxide and light results in more than 50% degradation of tretinoin in about 2 h and 95% in 24 h.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9990414&dopt=Abstract tretinoin Retin-A Renova