Carboxymethylcellulose sodium nacmc

Morphine FHC® 20 mg·mL⁻¹ (aqueous injectable solution) was purchased from FHC Farmacêutica, Lda (Mortágua, Portugal) and used as source of morphine hydrocloride (MH). Carboxymethylcellulose sodium (NaCMC; high viscosity: 700–1500 mPa·S) was acquired from Sigma Aldrich (Darmstadt, Germany). Methylparaben and propylparaben were obtained from Fagron Iberica (Barcelona, Spain). Glycerol was purchased from Vencilab (Vila Nova de Gaia, Portugal) and sterile water for injections was obtained from B. Braun Medical, Lda. (Queluz de Baixo, Portugal). IntraSite® Gel (Smith & Nephew, London, UK) and Varihesive® Hydrogel (Convatec, Reading, UK) were also used for comparison purposes. Acetonitrile HPLC-gradient grade (Panreac, Castellar del Vallès, Spain) and ethanol (Merck, Darmstadt, Germany) were also used. Tuffryn® membranes (polisulfone membrane disc filters, 0.45 µm) were purchased from the Pall Corporation (East Hills, NY, USA). All other ingredients used were of analytical grade or equivalent.

Neomycin was obtained from (Sisco Research Laboratories Pvt. Ltd., Taloja, Maharashtra, India). Tea tree oil was acquired from NOW^® Essential Oils (NOW Foods, Bloomingdale, IL, USA). Diethylene Glycol Monoethyl Ether (Transcutol^® P) was bought from Gattefosse SAS (Saint-priest Cedex-France). Tween 80 and Carboxymethylcellulose Sodium (NaCMC) were purchased from Sigma-Aldrich Co. (St Louis, MO, USA). Distearoyl phosphatidylethanolamine-N-[methoxy poly (ethylene glycol)-2000] (PEG-DSPE) was bought from Lipoid LLC., (Newark, NJ, USA). All other chemicals were of the finest grade available.