Ibuprofen

The materials used in the study included: ibuprofen (BASF AG, Ludwigshafen, Germany), microcrystalline cellulose (MCC; Person Pharmaceuticals Ltd., Backinghenshire, UK), dibasic calcium phosphate anhydrous, dihydrate, dicalcium phosphate (DCP) dihydrate (BDH Chemicals Ltd., Poole, UK), directly compressible lactose (BDH Chemicals Ltd.), xanthan gum (Myprotein Co., Manchester, UK), hydroxypropylmethylcellulose (Ranbaxy Laboratories Ltd., Gurgaon, India), and Irvingia gabonensis mucilage (from Irvingia gabonensis kernel (dika nut), bought on the local market at Okolobiri, Nigeria). The procedure for the extraction of the polymer has been reported elsewhere. 4, (link)12

Sodium deoxycholate (NaDC) was used as purchased from Sigma Aldrich, Dorset, UK (97 %). Analysed compounds using MLC were acetaminophen (99 %, Sigma Aldrich, Dorset, UK), acetyl salicylic acid (99 %, Acros organics, Geel, Belgium), caffeine (97 %, Sigma Aldrich, Dorset, UK), carbamazepine (99 %, Sigma Aldrich, Dorset, UK), cimetidine (Sigma Aldrich, Dorset, UK), diclofenac (98 %, TCI, Zwijndrecht, Europe), fenoprofen (97 %, Fluka, Dorset, UK), fluconazole (98 %, Sigma Aldrich, Dorset, UK), flurbiprofen (98 %, TCI, Zwijndrecht, Europe), gemfibrozil (98 %, TCI, Zwijndrecht, Europe), ibuprofen (98 %, BASF, Cheshire, UK), indomethacin (99 %, Sigma Aldrich, Dorset, UK), ketoprofen (98 %, Sigma Aldrich, Dorset, UK), lidocaine (98 %, Sigma Aldrich, Dorset, UK), lornoxicam (>98 %, TCI, Zwijndrecht, Europe), meloxicam (98 %, TCI, Zwijndrecht, Europe), naproxen (98 %, Sigma Aldrich, Dorset, UK), nicotinic acid (99.5 %, Sigma Aldrich, Dorset, UK), phenylbutazone (98.5 %, Sigma Aldrich, Dorset, UK), piroxicam (98 %, Sigma Aldrich, Dorset, UK), salicylic acid (99 %, Fisher Scientific, Loughborough, UK), theophylline (98 %, TCI, Oxford, UK) and terbutaline (96 %, Sigma Aldrich, Dorset, UK) used as purchased.
Deionised water was prepared using a Barnstead™ Ultrapure system.

Sodium deoxycholate (NaDC, 97%), sodium chloride (NaCl, analytical grade), sodium dihydrogen orthophosphate dihydrate (NaH 2 PO 4 .2H 2 O, 99%), disodium hydrogen orthophosphate anhydrous (Na 2 HPO 4, 99%) were purchased from Fisher Scientific (Loughborough, UK). The compounds of pharmaceutical interest considered in this work were caffeine 97% (Sigma-Aldrich, Dorset, UK), fenoprofen 97% (Fluka, Dorset, UK), quinine 96% (Fluka), acetaminophen 99% (Sigma-Aldrich), leflunomide 98% (Sigma-Aldrich), linezolid >98% (Sigma-Aldrich), ketoprofen 98% (Sigma-Aldrich), lidocaine 98% (Sigma-Aldrich), indomethacin 99% (Sigma-Aldrich), phenylbutazone 99% (Sigma-Aldrich), fluconazole 98% (Sigma-Aldrich), carbamazepine 99% (Sigma-Aldrich), cimetidine (Sigma-Aldrich), moexipril >98% (Sigma-Aldrich), naproxen 98% (Sigma-Aldrich), piroxicam 98% (Sigma-Aldrich), zolmitriptan >98% (Sigma-Aldrich), haloperidol 99% (Sigma-Aldrich), fosinopril >98% (Sigma-Aldrich), ibuprofen 98% (BASF, Cheshire, UK), diclofenac 98% (TCI Europe, Zwijndrecht, Belgium), flurbiprofen 98% (TCI Europe), gemfibrozil 98% (TCI Europe), theophylline 98%, (TCI, Oxford, UK), and meloxicam 98% (TCI Europe). Dialysis membrane was high retention, seamless, cellulose tubing with an average flat width of 23 mm and molecular weight cutoff of 12,400.

Paracetamol, polyvinyl alcohol (PVA, Mw 89,000-98,000, 99+% hydrolysed), polyethylene oxide (PEO) Mw 100,000 Da, PEO Mw 200,000 Da, poly (ethylene) glycol (PEG) Mw 4000 Da, and PEG Mw 30,000 Da were purchased from Sigma Aldrich UK. Ibuprofen was supplied by BASF SE (Ludwigshafen, Germany). Starch was obtained from BDH Chemicals (Poole, England). Sodium Starch glycolate was purchased from Shin-Etsu (Tokyo, Japan). Croscarmellose sodium was acquired from FMC Europe N.V. (Brussels, Belgium). Sodium lauryl sulphate (SLS) was supplied by Janssen Pharmaceuticals (Beerse, Belgium). Freeze dried strawberry powder was purchased from Healthy Suppliers (Hove, UK). Solvents were analytical grade.

Aqueous solutions of NaDC (97%), used as purchased from Sigma-Aldrich (Dorset, UK), were prepared by dilution from a 20 mM stock solution with distilled water as necessary to achieve concentrations of 7, 9, 11, 13, 17, and 20 mM (i.e., always at con-centrations greater than the stable micelle critical micellar concentration of NaDC 12 ). The following 24 compounds considered in this work were used as purchased: acetaminophen (99%; Sigma-Aldrich), acetyl salicylic acid (99%; Acros Organics, Geel, Belgium), alprenolol (98%; Sigma-Aldrich), amitriptyline (98%; Sigma-Aldrich), carbamazepine (99%; Sigma-Aldrich), cimetidine (Sigma-Aldrich), diclofenac (98%; TCI Europe, Zwijndrecht, Belgium), diphenhydramine (98%; TCI Europe), fenoprofen (97%; Fluka, Dorset, UK), fluconazole (98%; Sigma-Aldrich), flurbiprofen (98%; TCI Europe), gemfibrozil (98%; TCI Europe), ibuprofen (98%; BASF, Cheshire, UK), indomethacin (99%; Sigma-Aldrich), ketoprofen (98%; Sigma-Aldrich), lidocaine (98%, Sigma-Aldrich), mannitol (98%; Sigma-Aldrich), meloxicam (98%; TCI Europe), naproxen (98%; Sigma-Aldrich), phenylbutazone (99%; Sigma-Aldrich), piroxicam (98%, Sigma-Aldrich), propranolol (99%; Sigma-Aldrich), quinine (96%; Fluka), and terbutaline (96% Sigma-Aldrich). All experimental work was conducted without altering the pH or ionic strength to avoid the formation of a surfactant-gel hydropolymer.