1 EVALUATION OF THE LOCAL ANAESTHETIC EFFECTS OF THE METHANOL LEAF EXTRACT OF STERCULIA TRAGACANTHA LINDL. (1830) IN WEST AFRICAN DWARF GOATS BY UDEGBUNAM, RITA IJEOMA D.V.M (Nig), M.V.SC (Ibadan) PG/Ph.D/06/42080 A THESIS SUBMITTED TO THE DEPARTMENT OF VETERINARY SURGERY, FACULTY OF VETERINARY MEDICINE, UNIVERSITY OF NIGERIA, NSUKKA, FOR THE AWARD OF THE DEGREE OF DOCTOR OF PHILOSOPHY IN VETERINARY ANAESTHESIOLOGY MAY, 2011 2 CERTIFICATION UDEGBUNAM, RITA IJEOMA, a post-graduate student in the Department of Veterinary Surgery and with registration number PG/Ph.D/06/42080, has satisfactorily completed the requirements for the award of the degree of Doctor of Philosophy in Veterinary Anaesthesiology. The work embodied in this thesis is original and has not been submitted in part or full for any diploma or degree of this or any other university. …………………. ……………………. Prof. R.O.C. Kene Prof I.U. Asuzu Department of Veterinary Surgery, Department of Veterinary University of Nigeria. Physiology & Pharmacology (Supervisor) University of Nigeria (Supervisor) …………………………….. Prof. E.O. Gyang External Examiner …………………………… Dr. T.O. Nnaji (Acting Head of Department) 3 DECLARATION The studies presented in this thesis are original and were carried out by me under the supervision of Professors R.O.C Kene and I.U Asuzu. References made to the work of other investigators were duly acknowledged. No part of this thesis has been previously submitted elsewhere for a diploma or degree …………………………………… Udegbunam, Rita Ijeoma May, 2011 4 DEDICATION This thesis is dedicated in loving memory to Andrew Onebunne Nweke. 5 ACKNOWLEDGEMENTS I thank the Lord Almighty, the giver of all good gifts, knowledge and life for making this study possible. To Him be all Glory, honour and adoration forever. I also say thank you to my Supervisors, Prof R.O.C Kene and Prof I.U Asuzu for their immeasurable contributions to this work. Without your guidance and assistance, this work would not have been. Remain blessed. To by colleagues, in the Department of Veterinary Surgery, Drs. Eze, C.A; Nnaji, T.O; Onuba, A.C and Offor, G.E, I am most honored to be part of the surgery family. Thank you for your support. My thanks also go to the following: Prof J.O.A Okoye; Dr. E. Onuoha; Dr. R.C. Ezeokonkwo; Dr. R.I. Obidike, Dr. M.C.O. Ezeibe; Dr (Mrs) U. Okoroafor; Dr (Mrs) E.V. Ezenduka, Mrs. N. Nnaji; Mr. I.K. Ifedigbo, Mr I.I. Ogbudimkpa (late); Mr. A. Ngene; Mr. C. Nwaehujor and Dr. C.C. Onah for their help and input into this work. May God bless you all. My outmost gratitude goes to my siblings Chike, Chidi, Ifeyinwa, Okey, Ifeanyi and Chioma who supported me emotionally and financially. I lack the words to express my thanks. May the good Lord reward you all. To my mum, Theresa Ekeamaka Nweke, your prayers, calls, visits and advice are appreciated. May your days be long because you deserve the best from us. Thank you so much. My special thanks go to my husband, Dr. Sunday Ositadinma Udegbunam. I cannot thank you enough for your love, understanding and support. You were with me all the way. You are the best I can ask for. Somtochukwu, Chiagoziem and little Chiamaka, I say thank you to all of you for your understanding, love and support. May the Lord bless you all. 6 ABSTRACT This study investigated the local anaesthetic effects of the methanol leaf extract of Sterculia tragacantha (MEST) in WAD goats. The extract was prepared by cold maceration in 80% methanol to obtain a yield of 11.11%. The intraperitoneal (LD50) of the extract was found to be greater than 1600 mg/kg. Four preliminary experiments were carried out in mice and guinea pigs to evaluate the anti-nociceptive and anti-inflammatory effects of the extract. The anti-nociceptive effects were evaluated using guinea pig wheal test and acetic acid-induced writhing test. The effects of the extract on acute and chronic inflammation were evaluated using carrageenan induced paw edema and cotton pellet induced granuloma tests respectively. The preliminary screening of the extract for local anaesthetic activity in guinea pigs showed that injection of 10 mg/ml and 0.3 mg/ml solutions of the extract produced 100% and 86% analgesia respectively. Pretreatment of mice with the extract (300 and 600 mg/kg) significantly (p < 0.05) inhibited acetic acid induced pain and carrageenan- induced paw edema. Daily dosing of 300 and 600 mg/kg of the extract significantly (p < 0.05) suppressed granuloma formation in mice. The use of MEST (8 mg/kg) for infiltration anaesthesia prior to orchidectomy was also explored. The results of the study showed that the mean heart rate (HR) of MEST treated goats was significantly (p<0.05) lower than the mean HR obtained in group 1 (non anaesthetized orchidectomized) goats at 30 and 120 min of the study. The mean HR of the lignocaine (LIG) treated goats were significantly (p < 0.05) lower than that of the other groups throughout the post operative period. The mean respiratory rate (RR) of MEST group was significantly (p < 0.05) lower than RR of group 1 goats at 10, 30, 120 and 240 min. The LIG treated goats had significantly (p < 0.05) lower RR compared to groups 1 7 and 3 goats from 10 min of the study. The blood glucose of goats’ pretreated with MEST and LIG decreased at 30, 120 and 240 min while the glucose level of non anaesthetized orchidectomized goats increased at these time points post orchidectomy. The blood glucose values obtained in MEST and LIG groups were significantly (p < 0.05) lower than the glucose level of goats in group 1 at 30, 120 and 240 min post surgery. The mean pain scores obtained in the MEST and LIG pretreated orchidectomized goats were significantly (p < 0.05) lower than those obtained in non anaesthetized orchidectomized goats. No significant difference (p > 0.05) was observed between the pain scores of the MEST pretreated and LIG pretreated orchidectomized groups. The degree of analgesia and distance of diffusion of the MEST and LIG after flank infiltration were not significantly (p > 0.05) different. LIG produced a significantly (p < 0.05) longer duration of anaesthesia when compared to MEST. MEST was subjected to column and thin layer chromatography to separate its components. Seven fractions (F1-F7) were obtained at the end of chromatography and six fractions (F2-F7) were screened for local anaesthetic activity. F5 and F7 were more potent than LIG while F3, F5, F6 and F7 were more potent than MEST. Preliminary phytochemical tests revealed the presence of carbohydrates, starch, glycosides, alkaloids, flavonoids, terpenes, tannins and saponins in the crude extract. Fractions 5, 6 and 7 contained flavonoids, saponins and alkaloids. It was concluded that the methanol extract of S. tragacantha possessed peripheral analgesic, local anaesthetic and anti-inflammatory properties. The extract was effective as a local anaesthetic for orchidectomy in WAD goats. It also showed potent anaesthetic activity on flank infiltration. The fractions obtained showed significant local anaesthetic activity. The observed local anaesthetic activity of the plant extract and its fractions may be due to the presence of alkaloids and saponins in the leaves of S. tragacantha. 8 TABLE OF CONTENTS Title page -- -- -- -- -- -- -- -- -- i Certification -- -- -- -- -- -- -- -- -- ii Declaration -- -- -- -- -- -- -- -- -- iii Dedication -- -- -- -- -- -- -- -- -- iv Acknowledgments -- -- -- -- -- -- -- -- v Abstract -- -- -- -- -- --- -- -- -- vi Table of contents -- -- -- -- -- -- -- -- viii List of tables -- -- -- -- -- -- -- -- -- xvi List of figures -- -- -- -- -- -- -- -- -- xvii List of abbreviations -- -- -- -- -- -- -- -- xviii CHAPTER ONE GENERAL INTRODUCTION -- -- -- -- -- -- 1 1.1 Introduction -- -- -- -- -- -- -- -- -- 2 1.2 Research objectives -- -- -- - -- -- -- -- 4 CHAPTER TWO LITERATURE REVIEW -- -- -- -- -- -- -- 5 2.1 Pain -- -- -- -- -- -- -- -- -- 6 2.2 Physiology of Pain -- -- -- -- -- -- -- 6 2.2.1 Transduction of pain -- -- -- -- -- -- -- 6 2.2.2 Transmission of pain -- -- -- -- -- -- -- 8 2.2.3 Modulation of pain -- -- -- -- -- -- -- 9 2.2.4 Perception of pain -- -- -- -- -- -- -- 10 2.3 Types of pain -- -- -- -- -- -- -- -- 10 9 2.4 Local and systemic responses to noxious stimuli -- -- -- -- 12 2.4.1 Local biochemical responses to pain -- -- -- -- -- 12 2.4.2 Endocrine responses to pain -- -- -- -- -- -- 13 2.4.3 Metabolic responses to pain -- -- -- -- -- -- 14 2.4.4 Behavioral response to pain -- -- -- -- -- -- 14 2.5 Analgesia -- -- -- -- -- -- -- -- -- 16 2.6 Opioid analgesics -- -- -- -- -- -- -- 17 2.6.1 Morphine sulfate -- -- -- -- -- -- -- 18 2.6.2 Fentanyl citrate -- -- -- -- -- -- -- -- 18 2.6.3 Buprenorphine hydrochloride -- -- -- -- -- -- 19 2.6.4 Butorphanol tartrate -- - -- -- -- -- -- 19 2.6.5 Pentazocine -- -- -- -- -- -- -- -- 19 2.7 Non steroidal anti-inflammatory drugs (NSAIDs) -- -- -- 20 2.7.1 Inflammatory process -- -- -- -- -- -- -- 20 2.7.2 Mechanism of action of NSAIDs -- -- -- -- -- 21 2.7.3 Acetylsalicylic acid -- -- -- -- -- -- -- 22 2.7.4 Phenylbutazone -- -- -- -- -- -- -- -- 22 2.7.5 Flunixine meglumine -- -- -- -- -- -- -- 22 2.7.6 Indomethacin -- -- -- -- -- -- -- -- 23 2.7.7 Ketoprofen -- -- -- -- -- -- -- -- 23 2.7.8 Carprofen -- -- -- -- -- -- -- -- 23 2.7.9 Diclofenac -- -- -- -- -- -- -- -- 24 2.8 Local anaesthetics -- -- -- -- -- -- -- -- 24 2.8.1 General properties of local anaesthetics -- -- -- -- -- 24 2.8.2 Mechanism of action of local anaesthetics -- -- -- -- -- 25 10 2.8.3 Clinical pharmacology of local anaesthetics -- -- -- -- 25 2.8.4 Side effects