Qualifications:
BPharm, PhD (Rhodes)

Teaching

• Novel, controlled and sustained release drug delivery
• Biopharmaceutics and pharmacokinetics
• Dissolution
• Biological medicines
• Quality assurance and control

Research

Professor Walker runs an active research group that focuses on formulation and process development and design. Projects are undertaken within the current regulatory context and include development and validation of analytical tools for quality control and assurance. All projects make use of the principles of Quality by Design and entail risk assessment, design of experiments and application of Response Surface Methodology and mathematical modelling. Specifically, his current research focuses on the development, manufacture and assessment of solid oral extended release dosage forms, combination formulations, paediatric formulations, topical and transdermal drug delivery, regulatory sciences and policy development.

Recent research projects

• Niosome and liposome formulations for targeted delivery of therapeutic compounds
• Smart gels for drug delivery
• Floating technologies for treating diseases
• Solid lipid nanoparticle and nanostructured lipid nano-carriers for delivery of therapeutic compounds
• Microencapsulation
• Application of Quality by Design to formulation and analytical method development

Potential projects

• Development of formulations for difficult to treat diseases
• Manufacture of co-crystallised anti-retroviral compounds for enhanced therapy
• Combination dosage forms for the treatment of TB and other diseases
• Manufacture of SLN and NLC using high pressure homogenisation and ultrasound for targeted delivery
• Characterisation of oils as pharmaceutical excipients

Selected publications

• C.I. Nkanga, R.B.Walker and R.W. Krause

  pH-dependent release of isoniazid from isonicotinic acid (4-hydroxy-benzylidene)-hydrazide loaded liposomes. Journal of Drug Delivery Science and Technology, 45, 264-271 (2018).

• S. Yaripour, A. Mohammadi, I. Esfanjani, R.B. Walker and S. Nojavan

  Quantitation of zolpidem in biological fluids by electro-driven microextraction combine with HPLC-UV analysis. EXCLI Journal, 17, 349-361 (2018).

• P.A. Makoni, S.M.M. Khamanga, K. Wa Kasongo and R.B. Walker

  Development of a stability-indicating HPLC-ECD method for the analysis of efavirenz in formulations

  using experimental design, Pharmazie, 73(10),570-578 (2018)

• H.M.K. Veerubhotla and R.B.Walker

  Development and validation of a stability-indicating RP-HPLC method using quality by design for estimating captopril. Indian Journal of Pharmaceutical Sciences, 81(1), 45-56 (2019)

• B.A. Witika and R.B. Walker.

  Development, manufacture and characterization of niosomes for the delivery of nevirapine. Pharmazie 74(2), 91-96 (2019).

• A. Manda, R.B. Walker and S.M.M. Khamanga

  An artificial neural network approach to predict the effects of formulation and process variables on prednisone release from a multi-particulate system. Pharmaceutics 11(3), 109-127 (2019).

• C.I. Nkanga, X. Siwe Noundou, R.B. Walker and R.W. Krause

  Co-encapsulation of rifampicin and isoniazid in crude soybean lecithin liposomes. South African Journal of Chemistry 72(1), 80-87 (2019).

• P.A. Makoni, K. Wa Kasongo and R.B. Walker

  Short term stability testing of efavirenz-loaded solid lipid nanoparticles (SLN) and nanostructured lipid carrier (NLC) dispersions. Pharmaceutics 11(8), 397, 1-21 (2019). https://doi.org/10.3390/pharmaceutics11080397

• P.A. Makoni, M.T.R. Chikukwa, S.M.M. Khamanga and R.B. Walker.

  Stability Indicating HPLC-ECD method for the analysis of clarithromycin in pharmaceutical dosage forms: Method scaling versus re-validation. Scientia Pharmaceutica, 87(4), 31-51 (2019).

• P.V. Ntemi, R.B. Walker and S.M.M. Khamanga

  Design, evaluation and optimization of taste masked clarithromycin powder. Pharmazie, 74(12), 721-727 (2019).

• C.I. Nkanga, M. Roth, R.B. Walker, X. Siwe Noundou and R.W. Krause

  Co-loading of isoniazid-grafted phthalocyanine-in-cyclodextrin and rifampicin in crude soybean lecithin liposomes: Formulation, spectroscopic and biological characterization. Journal of Biomedical Nanotechnology 16, 14-28 (2020).

• P.A. Makoni, J. Ranchhod, K. Wa Kasongo and R.B. Walker

  The use of quantitative analysis and Hansen solubility parameter predictions for the selection of  excipients for lipid nanocarriers to be loaded with water soluble and insoluble compounds. Saudi Pharmaceutical Journal 28(3), 308-315 (2020).  doi: https://doi.org/10.1016/j.jsps.2020.01.010

• M. Chikukwa, M. Wesolv, A. Korzeniowska, P. Ciosek-Skibinska, R.B. Walker and S.M.M. Khamanga. Assessment of taste masking of captopril by ion-exchange resins using an electronic gustatory system. Pharmaceutical Development and Technology, 25(3), 281-289 (2020). https://doi.org/10.1080/10837450.2019.1687520

• B.A. Witika, V.J. Smith and R.B. Walker

  A comparative study of the effect of different stabilizers on the Critical Quality Attributes of self-assembling nano co-crystals. Pharmaceutics 12(2), 182, 1-15 (2020). https://doi.org/10.3390/pharmaceutics12020182

• H.M.K. Veerubhotla and R.B. Walker

  Application of a Plackett–Burman design for screening process variables likely to impact extrusion and spheronization of a formulation. Indian Journal of Pharmaceutical Sciences 82(1), 76-87 (2020).

• N.I. Okafor, C.I. Nkanga, R.B. Walker, X. Siwe Noundou and R.W. Krause

  Encapsulation and physicochemical evaluation of efavirenz in liposomes. Journal of Pharmaceutical Investigation 50 (2), 201-208 (2020) https://doi.org/10.1007/s40005-019-00458-8

• C Mwila and R.B. Walker

  Improved stability of rifampicin in acidic media in the presence of gastric-resistant isoniazid microspheres. Pharmaceutics  12(3), 234-262 (2020)  https://doi.org/10.3390/pharmaceutics12030234

• B.A. Witika, V.J. Smith and R.B. Walker

  Quality by design optimization of cold sonochemical synthesis of zidovudine-lamivudine nanosuspensions. Pharmaceutics 12 (4), 367 1-17 (2020). https://doi.org/10.3390/pharmaceutics12040367
• Bapolisi, C.I. Nkanga, R.B. Walker and R.W. Krause
• Simultaneous liposomal encapsulation of antibiotics and proteins: co-loading and characterization of rifampicin and human serum albumin in soy-liposomes. Journal of Drug Delivery Science and Technology 58(8), 1-12, (2020). Article 10751 https://doi.org/10.1016/j.jddst.2020.101751

• M.T.R. Chikukwa, R.B. Walker and S.M.M. Khamanga

  Formulation and characterization of  a combination captopril and hydrochlorothiazide microparticulate dosage form, Pharmaceutics 12(8), 712, 1-19 (2020).  https://doi.org/10.3390/pharmaceutics12080712

• A.F.B. Fauzee and RB Walker.

  The impact of formulation variables on the optimization of pilot scale cream formulations. Cogent Engineering, 7(1), 1-21 (2020). https://doi.org/10.1080/23311916.2020.1804713

• P.A. Makoni, K. Wa Kasongo and R.B. Walker

  Preformulation studies of efavirenz with lipid excipients using thermal and spectroscopic techniques. Pharmazie, 75(9), 417-423 (2020). https://doi.org/10.1691/ph.2020.0053

• B.A. Witika, P.A. Makoni, S.K. Matafwali, A.C. Kalungia, C. Mwila, A. Bapolisi, C.I. Nkanga, and R.B. Walker. Biocompatibility of biomaterials used in nanoencapsulation: Current approaches. Nanomaterials,  10 (9), 1649, 1-40 (2020). https://doi.org/10.3390/nano10091649

• S. Melamane, R.B. Walker and S.M.M. Khamanga

  Formulation optimization of smart thermosetting lamotrigine loaded hydrogels using response surface methodology, Box-Behnken design and artificial neural networks. Drug Development and Industrial Pharmacy, 46 (9), 1402-1415 (2020).  https://doi.org/10.1080/03639045.2020.1791163
• P. Mazonde, S.M.M. Khamanga and R.B. Walker. Design, optimization, manufacture and characterization of efavirenz-loaded flaxseed oil nano-emulsions. Pharmaceutics, 12(9), 797, 1-22 (2020). https://doi.org/10.3390/pharmaceutics12090797

• P.A. Makoni, S.M.M. Khamanga and R.B. Walker. Muco-adhesive clarithromycin-loaded nanostructured lipid carriers for ocular delivery: Formulation, characterization, cytotoxicity and stability. Journal of Drug Delivery Science and Technology (Accepted In Press) https://doi.org/10.1016/j.jddst.2020.102171

• B.A. Witika and R.B. Walker. Preformulation Characterization and identification of Excipients for Nevirapine Loaded Niosomes. Pharmazie (Accepted In Press)

Other publications

• R.B. Walker. Editorial: Times are changing. Controlled Release Society Newsletter, 34 (1) March 2017.

• R.B. Walker. Editorial: Wanted: Innovative, Translatable Science. Controlled Release Society Newsletter, 33(1) March 2016.

• R.B. Walker. Editorial: Exciting Science in Edinburgh. Controlled Release Society Newsletter, 32(4) August 2015

• R.B. Walker. Opinion Piece: What is the real need in low-income countries? Controlled Release Society Newsletter, 31(5) September 2014.

• A. Gray and R.B. Walker. Prescription medicine abuse, South African Pharmaceutical Journal, 78 (9), 56, October 2011.

• A. Attaran and R.B. Walker. Editorial: Shoppers Drug Mart or Poachers Drug Mart. Canadian Medical Association Journal, 178(3) 265-266 (2008).

Book chapters

• S.M.M. Khamanga and R.B. Walker. Science and practice of microencapsulation technology, in Multiparticulate Drug Delivery Systems: Formulation, processing and manufacturing, A.R. Rajabi-Siahboomi (ed), Springer, 2016 (In press).

• M. Almukainzi, N.A. Bou-Chacra, R.B. Walker and R. L?benberg. Biorelevant Dissolution Testing, in Therapeutic Delivery Solutions, C. Chan, K. Chow, B. McKay and M. Fung (eds.), John Wiley and Sons., Inc., 2014, pp 335 -.

• R.B. Walker. Modified release delivery systems for oral use in Modified-Release Drug Delivery Technology, Second Edition, Volume 1, M. Rathbone, J. Hadgraft, M. Roberts and M. Lane (eds), Drugs and the Pharmaceutical Sciences, Volume 183, Informa Healthcare, May 2008, pp 131-141.

• F.A. Chaibva and R.B. Walker. Analytical methods for the quantitative determination of oxytocin in Handbook of Oxytocin Research: Synthesis, Storage and Release, Action and Drug Forms, H. Jastrow and D. Feuerbach (eds), Endocrinology Research and Clinical Developments, Nova Science Publishers, Inc., 2009 pp 35-58.

• R.B. Walker, R.K. Verbeeck and I.Kanfer. Pharmaceutical Alternatives: Considerations for generic substitution in Generic Drug Product Development, I. Kanfer and L. Shargel (eds), Drugs and the Pharmaceutical Sciences, Volume 180, Informa Healthcare, November 2007, pp 32-41.

Awards and grants

South Africa – India NRF Research Grant 2016 - 2018

Academy of Pharmaceutical Sciences of South Africa Distinguished Teacher of the Year Award in 2000

Academic Pharmacist of the Year National Pioneer Pharmacy Award 2019

Web presence

Research Gate

https://www.researchgate.net/profile/Roderick_Walker

LinkedIn

https://www.linkedin.com/in/roderick-walker-286a5310/

Google Scholar

https://scholar.google.co.za/citations?user=WHlMVngAAAAJ&hl=en&oi=ao

Orcid ID

http://orcid.org/0000-0003-2781-4154

Scopus

https://www.scopus.com/authid/detail.uri?authorId=25230491600

Twitter

@RBWalker1

Recent former students

Doctor of Philosophy

Ayeshah Fateemah Bebee Fauzee - Establishing a formulation design space for a generic clobetasol 17-propionate cream using the principles of Quality by Design (2014).

Ashmita Raminah - Development and assessment of ketoconazole intravaginal thermosetting hydrogel formulations (2017).

Chiluba Mwila - The development, manufacture and evaluation of sustained release gastric-resistant isoniazid and gastro-retentive microporous microspheres (2018).

Melissa Tafadzwa Ruramai Chikukwa - Formulation and characterization of a combination captopril and hydrochlorothiazide microparticulate dosage form for paediatric use (2020).

Bwalya Angel Witika - Formulation development, manufacture and evaluation of a lamivudine-zidovudine nano co-crystal thermo-responsive suspension (2020). Pascal Vitalis Ntemi

Pascal Vitalis Ntemi - Formulation, development and assessment of Devil’s Claw loaded phyto-elastosomes in thermo-responsive hydrogels  (2020).

Master of Science (Pharmacy) in Pharmaceutics

Chiedza Cathrine Zindove - Development and assessment of sustained release stavudine loaded microparticles (2014).

Tendai Jonathon Chanakira - Development, manufacture and assessment of mometasone furoate loaded nanostructured lipid carriers (2014).

Pedzisai A Makoni - Formulation, development and assessment of efavirenz-loaded lipid nanocarriers (2014). Co-supervisor. Supervisor. Dr K Wa Kasongo

Samantha Yolanda Mukozhiwa Development and assessment of gastroretentive sustained release captopril tablets (2014). Co-supervisor. Supervisor Dr SMM Khamanga

Tawanda Gay Dube - Formulation, development and assessment of tenofovir disoproxil fumarate-loaded pellets (2015).

Henusha Devi Jhundoo - An investigation into the feasibility of incorporating ketoconazole into solid lipid microparticles (2015).

Farai Arthur Mhaka - Development and manufacture of sustained release captopril pellets (2015).

Sonja Koekemoer - Gradient high performance liquid chromatographic method for the simultaneous analysis of efavirenz, emtricitabine and tenofovir (2016).

Hari Mani Krishna Veerubhotla - Development of captopril pellets using the principles of Quality by Design (2016).

Janeeta Ranchhod - Formulation, development and evaluation of lipid nanocarriers for minocycline hydrochloride (2017).

Anjana Makan - Development and assessment of gastric-retentive sustained release metronidazole microcapsules (2017).

Bwalya Angel Witika - The development, manufacture and characterization of niosomes intended to deliver nevirapine to the brain (2017).

Shakemore Tinashe Kangausaru - Formulation development, manufacture and evaluation of hydralazine hydrochloride microspheres (2017). Supervisor. Co-supervisor Dr S.M.M. Khamanga

Pascal Vitalis Ntemi - Taste masking of clarithromycin with ion-exchange resins (2017).

Melissa Tafadzwa Ruramai Chikukwa - Preparation and evaluation of captopril-ion exchange resin complexes (2017)

Tanyaradzwa Gracious Musakana - The development, manufacture and evaluation of a self-micro-emulsifying drug delivery system for efavirenz (2018). 

Omoyosola Omolola Oridota - Development and assessment of gastroretentive sustained release captopril micro-balloons (March 2018).

Tsitsi Mudyahoto - Formulation, characterization and optimization of self-nanoemulsifying drug delivery systems (SNEDDS) loaded with artemether and lumefantrine (2018).

Grace Shalom Govere - Development and assessment of solid gliclazide-HPMC-AS dispersion delivery

systems (2018).

Siyabonga Melamane - Development and assessment of a smart thermosetting intranasal hydrogel for lamotrigine (2018).

Hariska Naidu - Development, formulation and assessment of an orodispersible taste-masked sildenafil film for paediatric use  (2019).

Arthur Manda - Application of Quality by Design to the manufacture of a multiparticulate prednisone dosage form (2019).

Fadzai Naomi Mungoshi - The development, manufacture and characterization of tenofovir encapsulated liposomes (2019).

Kudzai Gabriella Makoni - Preparation, characterization and optimization of carbamazepine based pellets prepared by extrusion-spheronization technique (2019).

Tavonga Tyomai Mandava - Development and assessment of a fixed dose combination of perindopril arginine and indapamide loaded microparticles (2020).

Professional affiliations

Registered with South African Pharmacy Council

Member of the Pharmaceutical Society of South Africa

Hobbies and interests

All sports, photography and reading