Sec 5 Pharmacology PDF

Spinal cord stimulants *muscular activity *reflex excitability *center strychnine and brucine. Strychnine Origin: It is an alkaloid from strychnus nux vomica seeds Pharmacological actions and MOA 1- Spinal cord stimulant: inhibit inhibitory transmitter glycine at post-synaptic nerve endings, so...

Spinal cord stimulants *muscular activity *reflex excitability *center strychnine and brucine. Strychnine Origin: It is an alkaloid from strychnus nux vomica seeds Pharmacological actions and MOA 1- Spinal cord stimulant: inhibit inhibitory transmitter glycine at post-synaptic nerve endings, so increase the reflex excitability to external stimuli. 2- Aphrodisiac: It stimulates the sex centers in spinal cord 3- General tonic and stomachic: orally, it stimulates taste buds of the tongue and gustatory buds of stomach due to its bitter taste 4- Neuromuscular purgative: By stimulation of aurbach’s plexus of the intestinal mucosa so, increase the intestinal motility. 5- Ruminal tonic: By increasing the ruminal motility Therapeutic uses  For weak and depilating animals.  For ruminal atony.  For sexual impotency in dogs.  It illegally used as motor activator for race horses to increase their capacity for running (doping). It is used as a poison for stray dogs. Toxicity The toxic symptoms are characterized by: Convulsions in all skeletal muscles and diaphragm at the same time.  Poisoned animal shows a characteristic posture (opisistonous form) i.e. back become arched, limbs become rigid and extended, head raised upward and backward and tail raised upward and forward.  Convulsions are interrupted by periods of rest or relaxation (tonic convulsions).  The period of convulsion increased by increasing the toxic dose. Death occurs due to asphyxia as a result of prolonged contraction of the diaphragm. Treatment of strychnine poisoning  Symptomatic ttt  Keep the animal in a dark place to avoid external stimuli.  Inhalation of volatile anesthetic as ether and chloroform to quiet the animal.  Artificial respiration or fresh oxygen supply to avoid asphyxia.  Administration of antidotes as: a- For horse: Chloral hydrate b- For dog: Barbiturates or bromides. c- For man: Mephenesin which act as a central skeletal muscle relaxant by blocking the spinal transmitters. Experiment Animal: frog Drugs: Strychnine sulphate of 1:10000 solution Thiopental sodium (Nesdonal) 1 % solution Route: SC in dorsal lymph sac Experiment: Exam writing: the unknown drug has spinal cord stimulating effect as Strychnine sulphate or has no effect  Experiment Observations 1. Frog with pithed brain & normal spinal cord 2. Frog with pithed brain & injected with strychnine sulphate 3. Frog with pithed spinal cord and injected with strychnine 4. Frog shows strychnine poisoning and injected with pentobarbitone solution. The anaesthetic drug is injected around a main nerve trunk supplying an area and prevents the conduction of impulses from this area through its nerve supply so it loses its sensation. It is called also regional anaesthesia. Indications diagnosis of lameness in equine induction of surgical operations in the posterior region as castration. Experiment Animal: frog Drugs: Amethocaine Route: arround sciatic nerve plexus Experiment: Exam writing: the unknown drug has Nerve blocking anaesthetic effect as Amethocaine or has no effect Foot withdrawal reflex The time interval control Amethocaine 0 - - 3 - + 5 - + 10 - + 15 - + 30 - +