Abstract

This work studied the various delivery systems (oral and parental formulations) of crude Cannabis. The stability, pharmacological and toxicological profiles of Cannabis resin in the formulations was also studied.

Dried powdered leaves of Cannabis sativa L. were extracted with chloroform, the extract was concentrated to obtain an oil-based tar (resin) and its phytochemical composition determined. The Cannabis crude resin was formulated as syrup, capsule and suppository dosage forms. The stability of the resin in the formulations was studied by accelerated stability technique. The in vivo release profile of the capsules was also studied. The antimicrobial activity of Cannabis crude resin was investigated using clinically isolated Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration (MIC) and killing rate constant against the organisms were determined by agar diffusion and viable count methods respectively. The anti-inflammatory effect of Cannabis crude resin and syrup formulations was studied using egg-albumin-induced paw oedema in rats. The acute toxicity (LDSo)of the crude extract was determined by the brine-shrimp method while effects on biochemical parameters (glutamate-pyruvate-transaminase, glutamate-oxaloacetate-transaminase and urea) haematological parameters (eosinophile, monocyte, neutrophiles and lymphocyte counts, packed-cell volume and red blood cells) were determined in Wistar rats after 1, 2 and 3 weeks of treatment. The, internal,acgans~(liver,heart, kidney, spleen, lungs and the brain) from the treated rats were examined histopathologically to ascertain degeneration on chronic administration of Cannabis crude resin. Results were analysed statistically using the Analysis of Variance (SPSS) and Student's t-test. Means that differed significantly were identified by the least significant difference (LSD) Post-hoc test at 95 % confidence interval i.e. (Pc0.05).

The result showed that the extraction process yielded 10 % (wlw) of the Cannabis crude resin. The presence of alkaloids, glycosides, saponins, tannin, terpenes and steroids was detected in the crude resin and dried plant. Cannabis crude resin syrup was stable even without the addition of EDTA with a shelf-life of 50 days. The degradation of Cannabis crude resin syrup formulation followed a first-order kinetic with the degradation rate constant of 0.0039 min-I. At a minimum inhibitory

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concentration (MIC) of 12.5 mglml, the chloroform, methylene chloride, ethanol, n-hexane: chloroform (1:l) and n-hexane extracts of Cannabis sativa showed significantly (Pc0.05) higher antimicrobial activity against S. aureus and Ps. aeruginosa than Penicillin G (MIC 18.0 mgfml). The crude resin syrup formulation exhibited a significant (Pc0.05) dose-related inhibition of paw edema in rats. The crude resin caused changes in biochemical and haematological parameters in a dose-dependent manner with no significant increase in the first two weeks of treatment, which markedly changed at week 3. The histopathological results of the various organs showed lesions of varied intensity suggesting possible toxicity in chronic use of Cannabis crude resin.

These findings suggest that crude Cannabis resin can be used for its antimicrobial and antiinflamatory effect and that its formulation into syrup favours its pharmacological activity and have good stability.

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Chapter One

1 .O        INTRODUCTION

For centuries, man has used various preparations of Cannabis saliva L. (Cannabinaceae) for their psychotomimetic and supposed medicinal effects. Since the pioneering studies of Emperor Shan Nung of China 2737 BC, 'this natural product has been investigated in various parts of the world for its potentially therapeutic uses. The world literature is replete with folkloric accounts of its use in medicine. The ancient world of the Middle East and Europe comprising Assyria, ancient Egypt, the Scythians, Judea and ancient Greece and Rome have reported its various medicinal

uses. The ancient Assyria of the sixth century B.C cultivated Cannabis for medical purpose. It was known as "qaunnabu" and externally it served as a constituent of various ointments for bruises and swellings, and as a bandage; its fumes were used for managing arthritis and it was prescribed for impotence.3

The  ancient Egyptians  also  used  Cannabis (called  "3MSM.T')  for   prevention

of/controlling haemorrhages in women during childbirth, in enemas, eye medication and bandages." In ancient Greece and Rome, though its psychotropic properties were not known but Cannabis was commonly used as a laxative, painkiller and an ointment for ear treatment. It was often linked to male impotence.677

In ancient India, Cannabis also referred to as "bhang" was prescribed for the treatment of fever, earache, lepyosy,,,g~n~r;rhoeaasthma, hysteria and sciatica. It was

also  believed  to   be   an   aphrodisiac.*'     The   leaves  were   recommended as

antiphlegmatic and also as a remedy for catarrh accompanied by diarrhoea. Marijuana - derived drugs were also used in the treatment of cramps, convulsion in children, headache, hysteria and tetanus. " Tetrahydrocannabinol (THC), in particular reduces intestinal mobility ''-I3. In ancient China, Cannabis also known as "Ma" was

reported to have psychotropic action. It was used in the treatment of rheumatism, haemorrhages during childbirth and vomiting. It was also used in combination with wine as an anaesthetic in major ~ ~ e r a t i o n s l ~The''~ .ancient Scythians, the medieval Arabs, the Syrians were all familiar with Cannabis even though they were more interested in the plant for religious rite17-19. Cannabis use in western Europe and America was only reported as late as lgth century by the following researchers: O'Shaughnessy, et a1 who all agreed on the fact that Cannabis has been in use for a very long time as a medicinal treatment for various maladies. 20-22 The 2oth century

use of Cannabis is restricted to the treatment of vomiting in cancer chemotherapy as well as an appetite stimulant.23,24 It is also used as a painkiller for excruciating pains in multiple sclerosis 25.26.

1.2 Historical Background of Marijuana (Cannabis)

Interest in drugs from Cannabis (marijuana) has had a long history of medical and therapeutic use in India and the middle ~ a s wheret~ ~it has been variously used as analgesic, anti-convulsant, antispasmodic, anti-emetic and hypnotic. Marijuana was introduced to British medicine in the mid-nineteenth century by O'Shanghnessy who had gained clinical experience with the drug as an Army Surgeon in ~ n d i a ~He~ . recommended its use for the relief of skin, muscle spasm, and convulsions occurring in tetanus, rabies, rheumatism and epilepsy29. Partly as a result of his advocacy Cannabis came to be widely used as an analgesic, anti-convulsant and anti-spasmodic throughout the middle part of the 191h century in Britain and the USA. However, the medical use of Cannabis declined around the turn of the 20"' century. Because the active constituents of Cannabis were not isolated until the second half of the 20Ih century, Cannabis continued to be used in the form of natural preparations which varied in purity and hence in effectiveness. The use of Cannabis was largely supplanted by other pharmaceutically purer drugs, which could be given in standardised doses to produce more dependable effects. These include the opiates, aspirin, chloral hydrate and thq.barbitluates30. The promulgations of laws in the early part of the 20Ih century also further discouraged the medicinal use of such Cannabis preparations, since Cannabis was treated as a "narcotic" drug. It finally disappeared from the American Pharmacopoeia in the 1940s after the passage of the Marijuana Tax A C ~ ~ ' .

Tetrahydrocannabinol (THC), the major psychoactive ingredient of Cannabis was not isolated until 1964~',shortly before Cannabis achieved widespread popularity as a recreational drug among American youths. Its widespread recreational use, and its symbolic association with a rejection of traditional social values, undoubtedly hindered pharmaceutical research into its therapeutic uses. Consequently, the rediscovery of some of its traditional therapeutic uses was largely serendipitous, as was the discovery of some newer uses. For example, its value as an anti-emetic agent in the treatment of nausea caused by cancer chemotherapy seems to have been rediscovered by young adults who had used