About

Michael M. Crowley, Ph.D., is an Adjunct Professor of Molecular Pharmaceutics and Drug Delivery at the University of Texas at Austin. He is also the President of Theridian Technologies, LLC, a pharmaceutical consulting group based in Austin, Texas, and a co-founder of Oticara, Inc., a specialty pharmaceutical company. His professional expertise includes drug delivery, product development, business development, and quality systems/regulatory consulting services to the pharmaceutical, drug delivery, and biotechnology industries. Dr. Crowley has over 30 years of experience in the field of drug delivery and pharmaceutical research. His previous management roles include positions at Monsanto Company, Warner-Jenkinson Company, and Mission Pharmacal. He earned his B.S. in Chemistry from the University of Missouri at St. Louis, an M.A. in Organic Chemistry from Washington University, and a Ph.D. in Pharmaceutics from The University of Texas at Austin, where he studied under Professor James McGinity. His research interests focus on physical pharmacy and pharmaceutical technology, particularly on novel drug delivery systems. He has presented his work at numerous national and international scientific symposia and conferences, authored peer-reviewed publications on topics such as hot-melt extrusion, amorphous dispersions, polymer stability, protein binding, analytical characterization of dosage forms, pulmonary drug delivery, and the mechanical properties of dosage forms. Additionally, Dr. Crowley authored chapters for the 2005 and 2012 editions of Remington: The Science and Practice of Pharmacy, holds five patents and several patent applications, and has served as a reviewer for scientific journals.

Research topics

• Materials science
• Chemical engineering
• Chemistry
• Composite material
• Process engineering

Selected publications

• Abuse-deterrent properties of REMOXY® ER, a high-viscosity extended-release oxycodone formulation

  Journal of Opioid Management · 2018-11-01 · 1 citations

  article

  OBJECTIVE: These in vitro studies compared abuse-deterrent properties of REMOXY ER (extended-release oxycodone), a novel, high-viscosity gel formulation, versus the two currently marketed ER oxycodone formulations. METHODS: Tampering methods were tailored to each product to maximize oxycodone release with the least complexity, time, and effort, based on the physical/chemical properties of each formulation. Oral abuse was simulated by extracting oxycodone from each manipulated formulation in Common Ingestible Liquids and in Advanced Solvents (not ingestible and requiring additional separation). To simulate injection abuse, oxycodone was extracted from each manipulated formulation in low volumes of injection vehicles, heated or unheated. Inhalation abuse potential was assessed by volatilization. RESULTS: In oral abuse simulations, manipulated REMOXY ER released 2-22 percent of its oxycodone in 20 minutes in five Common Ingestible Liquids, versus 77-85 percent oxycodone released from OxyContin® ER in 5 minutes in four of the five. In six Advanced Solvents, REMOXY ER released 3-37 percent at 20 minutes, versus 55-89 percent released from OxyContin ER at 5 minutes. Minimal oxycodone was extracted from REMOXY ER in five injection vehicles, heated or unheated. In contrast, OxyContin ER released 65-87 percent of its oxycodone within 10 minutes in all vehicles, regardless of heating. Xtampza® ER released 96 percent of its oxycodone in a heated injection vehicle and released 50-60 percent in two unheated injection vehicles. Showing minimal inhalation abuse potential, 9 percent of oxycodone was vaporized from manipulated REMOXY ER at 20 minutes compared to 8.8 percent at 5 minutes for OxyContin ER. CONCLUSIONS: In these studies, REMOXY ER demonstrated robust and meaningful abuse-deterrence relative to OxyContin ER and Xtampza ER. PERSPECTIVE: Abuse-deterrent drugs were intended to help fight opioid abuse. Yet, the persistence of the opioid epidemic indicates that vast improvements in abuse-deterrent technology are sorely needed. A new, high-viscosity, ER oxycodone formulation showed much improved abuse-deterrent properties in simulations of oral, injection, and inhalation abuse, compared to earlier, first-generation formulations.

  PublisherDOI

• Analytical Tools & Techniques in Hot Melt Extrusion & Case Studies on Formulation Development & Process Scale-Up

  2012-01-01 · 2 citations

  article
  Publisher

• Physicochemical properties of film-coated melt-extruded pellets

  Journal of Microencapsulation · 2007-01-01 · 26 citations

  article

  The purpose of this study was to investigate the physicochemical properties of poly(ethylene oxide) (PEO) and guaifenesin containing beads prepared by a melt-extrusion process and film-coated with a methacrylic acid copolymer. Solubility parameter calculations, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), modulated differential scanning calorimetry (MDSC), X-ray powder diffraction (XRPD) and high performance liquid chromatography (HPLC) were used to determine drug/polymer miscibility and/or the thermal processibility of the systems. Powder blends of guaifenesin, PEO and functional excipients were processed using a melt-extrusion and spheronization technique and then film-coated in a fluidized bed apparatus. Solubility parameter calculations were used to predict miscibility between PEO and guaifenesin, and miscibility was confirmed by SEM and observation of a single melting point for extruded drug/polymer blends during MDSC investigations. The drug was stable following melt-extrusion as determined by TGA and HPLC; however, drug release rate from pellets decreased upon storage in sealed HDPE containers with silica desiccants at 40 degrees C/75% RH. The weight loss on drying, porosity and tortuosity determinations were not influenced by storage. Recrystallization of guaifenesin and PEO was confirmed by SEM and XRPD. Additionally, the pellets exhibited a change in adhesion behaviour during dissolution testing. The addition of ethylcellulose to the extruded powder blend decreased and stabilized the drug release rate from the thermally processed pellets. The current study also demonstrated film-coating to be an efficient process for providing melt-extruded beads with pH-dependent drug release properties that were stable upon storage at accelerated conditions.

  PublisherDOI

• Pharmaceutical Applications of Hot-Melt Extrusion: Part I

  Drug Development and Industrial Pharmacy · 2007-01-01 · 804 citations

  review1st authorCorresponding

  Interest in hot-melt extrusion techniques for pharmaceutical applications is growing rapidly with well over 100 papers published in the pharmaceutical scientific literature in the last 12 years. Hot-melt extrusion (HME) has been a widely applied technique in the plastics industry and has been demonstrated recently to be a viable method to prepare several types of dosage forms and drug delivery systems. Hot-melt extruded dosage forms are complex mixtures of active medicaments, functional excipients, and processing aids. HME also offers several advantages over traditional pharmaceutical processing techniques including the absence of solvents, few processing steps, continuous operation, and the possibility of the formation of solid dispersions and improved bioavailability. This article, Part I, reviews the pharmaceutical applications of hot-melt extrusion, including equipment, principles of operation, and process technology. The raw materials processed using this technique are also detailed and the physicochemical properties of the resultant dosage forms are described. Part II of this review will focus on various applications of HME in drug delivery such as granules, pellets, immediate and modified release tablets, transmucosal and transdermal systems, and implants.

  PublisherDOI

• Pharmaceutical Applications of Hot-Melt Extrusion: Part II

  Drug Development and Industrial Pharmacy · 2007-01-01 · 346 citations

  review

  The advent of high through-put screening in the drug discovery process has resulted in compounds with high lipophilicity and poor solubility. Increasing the solubility of such compounds poses a major challenge to formulation scientists. Various approaches have been adopted to address this including preparation of solid dispersions and solid solutions. Hot-melt extrusion is an efficient technology for producing solid molecular dispersions with considerable advantages over solvent-based processes such as spray drying and co-precipitation. Hot-melt extrusion has been demonstrated to provide sustained, modified, and targeted drug delivery. Improvements in bioavailability utilizing the hot-melt extrusion technique demonstrate the value of the technology as a potential drug delivery processing tool. The interest in hot-melt extrusion technology for pharmaceutical applications is evident from the increasing number of patents and publications in the scientific literature. Part II of this article reviews the myriad of hot-melt extrusion applications for pharmaceutical dosage forms including granules, pellets, tablets, implants, transmucosal, and transdermal systems.

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• The influence of guaifenesin and ketoprofen on the properties of hot-melt extruded polyethylene oxide films

  European Journal of Pharmaceutical Sciences · 2004-06-22 · 117 citations

  article1st authorCorresponding
  PublisherDOI

• The Use of Near‐Infrared Spectroscopy for the Quantitation of a Drug in Hot‐Melt Extruded Films

  Drug Development and Industrial Pharmacy · 2004-01-01 · 30 citations

  article

  The objective of the study was to demonstrate the utility of near-infrared spectroscopy (NIRS) for quantitative analysis of a model drug in hot-melt extruded film formulations. Polyethylene oxide (PEO) films with clotrimazole (CT) as a model drug were prepared by hot-melt extrusion (HME) incorporating drug concentrations ranging from 0-20% and analyzed using a Fourier transform near-infrared (FT-NIR) spectrophotometer in the reflectance mode, High performance liquid chromatography (HPLC) was the reference method used for this study. The NIR calibration model derived for CT was composed of 21 frequency ranges that were correlated to the values quantified using the HPLC reference method. The NIR method developed resulted in an assayed CT amount in the film matrix to be within 3.5% of the quantity determined by the reference method. These studies clearly demonstrate that NIRS is a powerful method for the quantitation of active drug substances contained in films produced by HME and warrants further investigation.

  PublisherDOI

• Physicochemical and mechanical characterization of hot-melt extruded dosage forms

  Texas ScholarWorks (Texas Digital Library) · 2003-01-01 · 5 citations

  dissertationOpen access1st authorCorresponding

  The physicochemical and mechanical properties and the mechanisms of drug release from drug delivery systems prepared by hotmelt extrusion were investigated.The influence of processing conditions and the thermal properties of the polymeric retardants was also studied.The stability of polyethylene oxide (PEO) in sustained release tablets prepared by hot-melt extrusion was investigated.The chemical stability of PEO was found to be dependent on the storage and processing temperature, the screw speed and the molecular weight of the polymer.Lower molecular weight PEO MW = 100,000 (PEO 100K) was demonstrated to be a suitable processing aid for PEO 1M.Vitamin E, Vitamin E Succinate and Vitamin E TPGS were found to be suitable stabilizers for PEO; however, ascorbic acid was shown to degrade the polymer in solution.Drug release rates from hot-melt extruded tablets

  Publisher

• Physicochemical properties and mechanism of drug release from ethyl cellulose matrix tablets prepared by direct compression and hot-melt extrusion

  International Journal of Pharmaceutics · 2003-12-04 · 254 citations

  article1st authorCorresponding
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• Stability of polyethylene oxide in matrix tablets prepared by hot-melt extrusion

  Biomaterials · 2002-09-17 · 218 citations

  article1st authorCorresponding
  PublisherDOI

Frequent coauthors

• James W. McGinity

  The University of Texas at Austin

  7 shared

• Shawn A. Kucera

  Cassava Sciences (United States)

  3 shared

• Feng Zhang

  The University of Texas at Austin

  3 shared

• Suneela Prodduturi

  University of Mississippi

  2 shared

• Michael A. Repka

  University of Mississippi

  2 shared

• Sunil Kumar Battu

  University of Mississippi

  2 shared

• Sampada B. Upadhye

  Catalent (United States)

  2 shared

• Michael A. Repka

  University of Mississippi

  2 shared

Awards & honors

• co-inventor on five patents