Ehab A. Fouad

The use of spray-drying to enhance celecoxib solubility

The present research investigates the enhancement of the dissolution rate of celecoxib by using spray-drying to prepare a solid dispersion with various polymers, namely Kollicoat IR® (Kollicoat), polyvinyl alcohol (PVA) 22000, or polyethylene glycol 6000 (PEG). The investigated drug-to-polymer mass ratios were 1:1, 1:2, and 1:4 by weight. Hydroalcoholic or methylene chloride solvent systems were used. The obtained yields ranged from 65% to 78%, whereas the entrapment efficiencies were between 68% and 82%. The results revealed an increase in the dissolution rate of the prepared particles up to 200% within 20 min. The prepared particles were investigated using differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The increased dissolution rate was attributed to hydrogen bond formation between celecoxib and each polymer together with the reduced size of the formed particles offering a greater overall surface area. It was concluded that spray-drying may be considered a successful one-step technique to improve the dissolution rate of celecoxib when using Kollicoat, PVA, or PEG as the carrier polymer.

Pharmacokinetics of controlled release morphine (MST) in patients with liver carcinoma

BACKGROUND There are no studies reported on the pharmacokinetics of controlled release morphine (MST) in patients with hepatocellular carcinoma, the fifth most common cancer in the world. METHODS We have studied the pharmacokinetic profile of MST (30 mg) in 15 patients with liver carcinoma (eight with primary carcinoma on top of chronic hepatitis C, and seven with secondary metastatic liver malignancy as a result of other primary) compared with our previously published data for 10 healthy controls. Plasma morphine concentrations were measured in venous blood samples at intervals up to 12 h by high-pressure liquid chromatography. Total body clearance (Cl) and systemic bioavailability were estimated using a compartmental method. RESULTS Morphine bioavailability showed a substantial increase in patients with primary liver and secondary metastatic carcinoma than that of controls (64.8, 62.1, and 16.8%, respectively). The area under the serum concentration-time curve increased 4-fold in primary carcinoma (416 [sem25] microg h(-1) litre(-1)) and 3-fold (303 [21] microg h(-1) litre(-1)) in metastatic liver patients compared with healthy control (92.5 [3] microg h(-1) litre(-1)). No significant difference was found in T(max) between the two malignant groups but C(max) was significantly greater in primary liver carcinoma patients. Impaired morphine elimination was noted in primary carcinoma only (t(1/2) 5.99 [0.39] h). CONCLUSION Careful administration of morphine is recommended in patients with liver cancer.

The effect of rectal ozone on the portal vein oxygenation and pharmacokinetics of propranolol in liver cirrhosis (a preliminary human study)

AIM The aim of this study was to investigate the effect of rectal ozone on portal vein oxygenation and the pharmacokinetic changes of propranolol in patients with liver cirrhosis. METHODS Fifteen patients with liver cirrhosis were included They were given a fixed oral dose of propranolol 80mg on the morning of day 1 after overnight fasting. Blood samples were collected at fixed time intervals for 24h. Patients were given 12 sessions of rectal ozone of 300ml of 40% ozone/oxygen mixture. On day 14 another oral dose of 80mg propranolol was given and blood samples were collected as on day 1. Plasma concentrations of propranolol were measured by HPLC. Portal vein oxygen tension and saturation were measured before and after rectal ozone. RESULTS Plasma concentrations of propranolol were reduced after ozone therapy with pronounced decreases in the maximum plasma concentration and the area under the plasma concentration-time curve. The changes were consistent with a decrease in propranolol bioavailability. There was a decrease in the elimination half-life and mean residence time. Portal vein oxygenation significantly increased after rectal ozone. CONCLUSIONS The changes in the pharmacokinetics of propranolol probably reflect an increase in the rate and extent of its metabolism resulting from improved portal vein oxygenation attributable to the ozone therapy. The present work highlights that ozone can be an alternative medical measure to improve portal vein oxygenation in liver cirrhosis.

Technology evaluation: Kollicoat IR

Introduction: Developments in industrial pharmacy are often linked to the discovery of pharmaceutical excipients. Although recently introduced as a material for immediate release coatings, Kollicoat IR already has other applications. Areas covered: In this review, the different properties and pharmaceutical applications of Kollicoat IR as an excipient are discussed. In the first part, the chemical structure and the physicochemical characteristics are examined. The second part is a presentation of the available Kollicoat IR products followed by a brief overview of the preclinical studies completed for its use as an instant release coating material. Expert opinion: Although the polymer was intended as an immediate release coating material for tablets, grafting PEG with polyvinyl alcohol to form this polymer provides physicochemical properties that lead to ever-broadening applications. Understanding its properties can lead to the development of a new use for Kollicoat IR. The addition of Kollicoat IR to an ethylcellulose or polyvinyl acetate tablet coat was successful at modifying the drug release rate. Designing a successful controlled release coat simply requires acknowledgment of the drug release mechanism from the mixture of polymers that includes Kollicoat IR. Moreover, the interaction between Kollicoat IR and poorly soluble drugs produces fast-dissolving solid dispersions prepared using hot stage extrusion, spray drying, or freeze drying.

Preparation and investigation of acetyl salicylic acid-caffeine complex for rectal administration

An acetyl salicylic acid-caffeine complex was prepared and evaluated for the potential use in rectal administration. The results revealed the formation of a complex between acetyl salicylic acid and caffeine in a 1:1 molar ratio by a charge transfer mechanism. The effects of acetyl salicylic acid and complex on the rectal tissues showed destruction in the mucosal epithelium in case of acetyl salicylic acid; however, no change in the rectal tissues was noticed upon the administration of the complex. The effect of suppository bases on the release of the complex was studied using Witepsol H15 as fatty base and polyethylene glycols (PEG) 1000 and 4000 as a water soluble suppository base. The release profiles of acetyl salicylic acid and the complex were faster from PEG than from that of Witepsol H15. The percent release for the complex and acetyl salicylic acid from PEG base were 45.8, and 34.9%, respectively. However, it was 8.7 and 7.8%, respectively, from Witepsol H15 fatty base. The release kinetic was found to follow the non-Fickian diffusion model for complex from the suppository bases. It was concluded that acetyl salicylic acid caffeine complex can be used safely for rectal administration.

Pharmacokinetic studies of naproxen amides of some amino acid esters with promising colorectal cancer chemopreventive activity

Naproxen (nap) is belonging to Non-steriodal anti-inflammatory drugs (NSAIDs) group of drugs that characterized by their free carboxylic group. The therapeutic activity of nap is usually accompanied by GI untoward side effects. Recently synthesized naproxen amides of some amino acid esters prodrugs to mask the free carboxylic group were reported. Those prodrugs showed a promising colorectal cancer chemopreventive activity. The current study aims to investigate the fate and hydrolysis of the prodrugs kinetically in different pH conditions, simulated gastric and intestinal fluids with pHs of 1.2, 5.5 and 7.4 in vitro at 37 °C. The effect of enzymes on the hydrolysis of prodrugs was also studied through incubation of these prodrugs at 37 °C in human plasma and rat liver homogenates. The pharmacokinetic parameters of selected prodrugs and the liberated nap were studied after oral and intraperitoneal administration in male wistar rats. The results showed the hydrolysis of naproxen amides of amino acid esters to nap through two steps first by degradation of the ester moiety to form the amide of nap with amino acid and the second was through the degradation of the amide link to liberate nap. The two reactions were followed and studied kinetically where K1 and K2 (rate constants of degradation) is reported. The hydrolysis of prodrugs was faster in liver homogenates than in plasma. The relative bioavailability of the liberated nap in vivo was higher in case of prodrug containing ethyl glycinate moiety than that occupied l-valine ethyl ester moiety. Each of nap. prodrugs containing ethyl glycinate and l-valine ethyl ester moieties appears promising in liberating nap, decreasing direct GI side effect and consequently their colorectal cancer chemopreventive activity.