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Drug release responses of zinc ion crosslinked poly(methyl vinyl ether-co-maleic acid) matrix towards microwave

Wong TW, Wahab S, Anthony Y

Int J Pharm, 2008 Jun 5;357(1-2):154-63.
PMID: 18329203 DOI: 10.1016/j.ijpharm.2008.01.047

The drug release characteristics of beads made of poly(methyl vinyl ether-co-maleic acid) using Zn2+ as the crosslinking agent were investigated with respect to the influence of microwave irradiation. The beads were prepared by an extrusion method with sodium diclofenac as a model water-soluble drug. They were subjected to microwave irradiation at 80W for 5 and 20 min, and at 300W for 1 min 20s and 5 min 20s. The profiles of drug dissolution, drug content, drug-polymer interaction and polymer-polymer interaction were determined by dissolution testing, drug content assay, differential scanning calorimetry and Fourier transform infrared spectroscopy. Treatment of beads by microwave at varying intensities of irradiation can aid to retard the drug release with a greater reduction extent through treating the beads for a longer duration of irradiation. The treatment of beads by microwave induced the formation of multiple polymeric domains of great strength and extent of polymer-polymer and drug-polymer interaction. The release of drug from beads was retarded via the interplay of O-H, N-H, C-H, (CH2)n and C-O functional groups of these domains, and was mainly governed by the state of polymer relaxation of the matrix unlike that of the untreated beads of which the release of drug was effected via drug diffusion and polymer relaxation. In comparison to Ca2+ crosslinked matrix which exhibited inconsistent drug release retardation behavior under the influence of microwave, the extent and rate of drug released from the Zn2+ crosslinked beads were greatly reduced by microwave and the release of drug from these beads was consistently retarded in response to both high and low intensity microwaves.
Effects of microwave on drug release property of poly(methyl vinyl ether-co-maleic acid) matrix

Wong TW, Wahab S, Anthony Y

Drug Dev Ind Pharm, 2007 Jul;33(7):737-46.
PMID: 17654022

The drug release behavior of beads made of poly(methyl vinyl ether-co-maleic acid) was investigated with respect to the influence of microwave irradiation. The beads were prepared by an extrusion method with sodium diclofenac as a model water-soluble drug. The beads were subjected to microwave irradiation at 80 W for 5 and 20 min, and at 300 W for 1 min 20 s and 5 min 20 s. The profiles of drug dissolution, drug content, drug-polymer interaction, and polymer-polymer interaction were determined by using dissolution testing, drug content assay, differential scanning calorimetry, and Fourier transform infra-red spectroscopy. Keeping the level of supplied irradiation energy identical, treatment of beads by microwave at varying intensities of irradiation did not bring about similar drug release profiles. The extent and rate of drug released from beads were markedly enhanced through treating the samples by microwave at 80 W as a result of loss of polymer-polymer interaction via the (CH(2))(n) moiety, but decreased upon treating the beads by microwave at 300 W following polymer-polymer interaction via the O-H, COOH, and COO(-) moieties as well as drug-polymer interaction via the N-H, O-H, COO(-), and C-O moieties. The beads treated by microwave at 300 W exhibited a higher level of drug release retardation capacity than those that were treated by microwave at 80 W in spite of polymer-polymer interaction via the (CH(2))(n) moiety was similarly reduced in the matrix. The mechanism of drug release of both microwave-treated and untreated beads tended to follow zero order kinetics. The drug release was markedly governed by the state of polymer relaxation of the matrix and was in turn affected by the state of polymer-polymer and/or drug-polymer interaction in beads.
Endoscopic ultrasound-guided tissue acquisition with or without macroscopic on-site evaluation: randomized controlled trial

Chong CCN, Lakhtakia S, Nguyen N, Hara K, Chan WK, Puri R, et al.

Endoscopy, 2020 10;52(10):856-863.
PMID: 32498098 DOI: 10.1055/a-1172-6027

BACKGROUND: The use of macroscopic on-site evaluation (MOSE) to estimate the adequacy of a specimen for histological diagnosis during endoscopic ultrasound (EUS)-guided fine-needle tissue acquisition (FNTA) has recently been advocated. This study aimed to evaluate the diagnostic yield of MOSE compared with conventional EUS-FNTA without rapid on-site evaluation (ROSE).
METHODS: This was an international, multicenter, prospective, randomized controlled study. After providing informed consent, consecutive adult patients referred for EUS-FNTA for solid lesions larger than 2 cm were randomized to a MOSE arm or to a conventional arm without ROSE. A designated cytopathologist from each center performed all cytopathological examinations for that center and was blinded to the randomization results. The primary outcome measure was the diagnostic yield, and the secondary outcomes included sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy, and the rate of procedure-related complications.
RESULTS: 244 patients (122 conventional, 122 MOSE) were enrolled during the study period. No significant differences between the two arms were found in procedure time or rate of procedure-related adverse events. The diagnostic yield for the MOSE technique (92.6 %) was similar to that for the conventional technique (89.3 %; P = 0.37), with significantly fewer passes made (median: conventional 3, MOSE 2; P
Consensus guidelines on the optimal management in interventional EUS procedures: results from the Asian EUS group RAND/UCLA expert panel

Teoh AYB, Dhir V, Kida M, Yasuda I, Jin ZD, Seo DW, et al.

Gut, 2018 Jul;67(7):1209-1228.
PMID: 29463614 DOI: 10.1136/gutjnl-2017-314341

OBJECTIVES: Interventional endoscopic ultrasonography (EUS) procedures are gaining popularity and the most commonly performed procedures include EUS-guided drainage of pancreatic pseudocyst, EUS-guided biliary drainage, EUS-guided pancreatic duct drainage and EUS-guided celiac plexus ablation. The aim of this paper is to formulate a set of practice guidelines addressing various aspects of the above procedures.
METHODS: Formulation of the guidelines was based on the best scientific evidence available. The RAND/UCLA appropriateness methodology (RAM) was used. Panellists recruited comprised experts in surgery, interventional EUS, interventional radiology and oncology from 11 countries. Between June 2014 and October 2016, the panellists met in meetings to discuss and vote on the clinical scenarios for each of the interventional EUS procedures in question.
RESULTS: A total of 15 statements on EUS-guided drainage of pancreatic pseudocyst, 15 statements on EUS-guided biliary drainage, 12 statements on EUS-guided pancreatic duct drainage and 14 statements on EUS-guided celiac plexus ablation were formulated. The statements addressed the indications for the procedures, technical aspects, pre- and post-procedural management, management of complications, and competency and training in the procedures. All statements except one were found to be appropriate. Randomised studies to address clinical questions in a number of aspects of the procedures are urgently required.
CONCLUSIONS: The current guidelines on interventional EUS procedures are the first published by an endoscopic society. These guidelines provide an in-depth review of the current evidence and standardise the management of the procedures.