Dr Kerr H Matthews
k.h.matthews@rgu.ac.uk
+44 (0) 1224 262546
PC18b
Lecturer in Pharmaceutics
Key duties and responsibilities
I teach on a variety of undergraduate modules across all four years that include, Physical Pharmacy, Dosage Form Design, Industrial Pharmacy, Drug Delivery Systems, Research Methods, Advances in Pharmaceutical Science and Research Projects. Currently the Year leader for MPharm2, I am also Module Co-ordinator for Advanced Sciences in Professional Practice, part of the Overseas Pharmacists Assessment Programme (OSPAP). Committee membership extends from the MPharm and OSPAP Programme Management Teams to the School Research Committee and Undergraduate Recruitment & Marketing Committee. At postgraduate/research level, I am Research Supervisor to a total of four PhD and three MSc students (one as Principal Investigator).
Academic background
I joined the School of Pharmacy at RGU in October 2004 from the University of Strathclyde where I was a Lecturer in Drug Delivery and Formulation (2002-2004). Prior to this I held a Pfizer Fellowship (1999-2002) in Tissue Repair & Wound Healing, spending twenty months in the laboratories of Pfizer GRD Ltd., Sandwich, Kent, developing my novel foundation technology for the topical application of therapeutic agents directly to the surface of suppurating wounds. An International Patent Application was published with full Search Report in 2002 and the US patent granted soon after. Other than the four fellowships held (see below) I have undertaken a variety of industrial roles, most recently with ‘Scherer DDS Ltd’ (subsequently ‘Cardinal Health’ and now ‘Catalent’) that have included both Senior Scientist and Quality Officer.
Degrees -
BSc (Hons) in Chemistry (Strathclyde) 1985
PhD in Chemistry (Strathclyde) 1989
CChem MRSC (1993)
Fellowships held -
IRC in Polymer Science and Technology (Leeds) 1989 - 1992
AIST Fellowship (Tsukuba, Japan) 1992 - 1993
STA Fellowship (Tsukuba, Japan) 1994 - 1995
Pfizer Fellowship (Strathclyde & Sandwich) 1999 - 2002
Current research interests
Topical drug delivery to wounds
Lyophilised wafers have been developed as bioadhesive matrices for the topical application of therapeutic agents directly to the surface of suppurating wounds. These stable solid dosage forms are obtained by the freeze-drying of polymer solutions and gels containing either soluble or insoluble (as a suspension) compounds (Fig.1).
Fig.1. Schematic diagram of the formulation, manufacture and application of lyophilised wound healing wafers.
As freeze-drying is a low temperature process, it is suitable for formulating thermosensitive compounds. Additionally, if compounds are hydrolysed in conventional water-based formulations, lyophilised dosage forms provide a stable, alternative dosage form with a long shelf-life. The light and porous nature of lyophilised products (Fig.2) result in fast fluid uptake and natural bioadhesive properties that can be exploited in many pharmaceutical applications.
Fig.2 Scanning electron micrograph of a lyophilised wafer.
Lyophilised wafers were originally developed as a vehicle for the delivery of proprietary wound healing compounds. One of those compounds was an inhibitor of stromelysin-1, or matrix metalloproteinase-3 (MMP-3), known to be up-regulated in chronic wounds. The wafer was, in principle,
the ideal vehicle for delivering the therapeutic agent directly to the wound-bed despite the considerable presence of wound exudates (Fig.3).
Fig.3 Scanning electron micrograph of a lyophilised wafer containing an insoluble MMP-3 inhibitor.
In vitro models for suppurating wounds have also been developed and the flow behaviour of gels reconstituted from wafers as well as the release of contained compounds can be qualitatively and quantitatively assessed using these models in combination with flow rheometry (Fig.4a,b).
Fig.4 (a) Photographs of sodium alginate wafers modified with varying quantities of methylcellulose (Type I) and containing fluorescein, that have been reconstituted as gels/viscous solutions on a gelatine medium at 4 hours(left-hand image) and 24 hours (right-hand image).
(b) Rheograms (plots of shear stress as a function of shear rate ie ‘apparent viscosity’) for lyophilised wafers (Type I) reconstituted with volume equivalents of distilled water. The measured rheology reflects the flow behaviour on the in vitro model illustrated in Fig. 4b.
Further studies demonstrated the effect of gamma-irradiation on lyophilised wafers and it was concluded that wafers fabricated from sodium alginate and sodium alginate/methylcellulose combinations (Type I) were degraded by exposure to sterilising doses of gamma-rays. In contrast, xanthan gum (Type II) appeared to tolerate increased doses of irradiation with no detrimental effects on the flow properties of the gels formed from reconstituted wafers, Fig.5.
Fig.5 Rheograms for lyophilised wafers reconstituted with volume equivalents of distilled water following irradiation of 25 and 40 kGy.
Lyophilised wafers are currently being further developed as bioadhesive vehicles for the targeted and controlled delivery of precise amounts of broad-spectrum antimicrobial compounds used to treat wound infections. It is generally accepted that excessive and indiscriminate use of antimicrobial agents in hospitals may have exacerbated the evolution of resistant strains of common bacteria. It is postulated that the sustained application of precise amounts of antimicrobials accurately to the target area will be more efficacious in controlling the bacterial content of chronic wounds and help in the fight against hospital infection. This work is currently being conducted at postgraduate level.
Other research interests
I have other ongoing interests that include novel dosage forms for both humans and animals; tablet erosion in the stomach; intravenous formulation of insoluble drugs and the general application of polymers in the pharmaceutical sciences.
Funding
School of Pharmacy & Life Sciences, Tenovus Scotland, Cystinosis Foundation UK.
Key Publications
Boateng, J., Matthews, K., Stevens, HNE., Eccleston, G.M., 2009. Development and mechanical characterisation of solvent-cast polymeric films as potential drug delivery systems to mucosal surfaces. Drug.Dev.Ind.Pharm. (in press).
Matthews, KH., 2008. Freeze-drying of shaped pharmaceutical dosage forms. Ind.Pharm., Issue 20, 9-11.
Boateng, J., Matthews, K., Stevens, HNE., Eccleston, GM., 2008. Wound healing dressings and drug delivery systems - a review. J.Pharm.Sci., 97(8), 2892-2923.
Matthews, K.H., Stevens, H.N.E., Auffret, A.D., Humphrey, M.J., Eccleston, G.M., 2008. Formulation, stability and thermal analysis of lyophilised wound healing wafers containing an insoluble MMP-3 inhibitor and a non-ionic surfactant. Int.J.Pharm.,356, 110-120.
Matthews, K.H., Stevens, H.N.E., Auffret, A.D., Humphrey, M.J., Eccleston, G.M., 2006. Gamma-irradiation of wound healing wafers. Int.J.Pharm., 313, 78-86.
Matthews, K.H., Stevens, H.N.E., Auffret, A.D., Humphrey, M.J., Eccleston, G.M., 2005. Lyophilised wafers as a drug delivery system for wound healing containing methylcellulose as a viscosity modifier. Int.J.Pharm., 289, 51-62.
Matthews, K.H., Stevens, H.N.E., Auffret, A.D., Humphrey, M.J., Eccleston, G.M., 2003. Wafer for Wounds, Pfizer Ltd., International Application WO 03/037395 A1, 08 May.
Matthews, K.H., Stevens, H.N.E., Auffret, A.D., Humphrey, M.J., Eccleston, G.M., 2003. Wafer, Pfizer Inc., US 2,003,099,693 A1, 29 May.
Recent Conference Presentations
Matthews, KH., Labovitiadi, O., Lamb, A., 2008. Microbiological (MRSA) and rheological testing of antimicrobial karaya wafers. J.Pharm.Pharma., 60(Supplement 1), 36, A-15.
Matthews, KH., Labovitiadi, O., Lamb, A., 2008. Rheological investigation of some common polymer gels ands their synergistic combinations. J.Pharm.Pharma., 60(Supplement 1), 105, A-42.
Matthews, K.H., 2007. Determination of Tg´ in freeze-concentrated xanthan gels. http://www.parthen-impact.com/eventure/welcome.do?type=public&congress=49_7001#46630 (PSWC 2007).
Matthews, K.H., Stevens, H.N.E., Auffret, A.D., Humphrey, M.J., Eccleston, G.M., 2007. Accelerated ageing of gamma-irradiated lyophilised wafers containing an insoluble API. J.Pharm.Pharma., 59 (Supplement 1), 109, A-41 (BPC 2007).
