9.Evaluation analgesic effects by hot plate apparatus - Copy.pptx

9.Evaluation analgesic effects by hot plate apparatus - Copy.pptx

• 1.
  Evaluation of analgesiceffects by hot plate apparatus Dr. Mahmood Salim
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  Pain “An unpleasantemotional experience usually initiated by noxious stimulus and transmitted over a specialized neural network to the CNS” The word pain is derived from the Latin word Peone Greek word Poine meaning penalty or punishment
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  Cross Roads fortransmission of pain and its response by the body:  Receptors - free nerve endings Electro-chemical transmission Synapse in the spinal cord - convergence Ascent in the spinal cord to pain receiving areas in the brain  Facilitatory/Inhibitory neurons Motor response
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  Initiation of theresponse Algesic ( pain producing ) Substances: BK - Bradykinin  5-HT - Serotonin H+ Acidic substance  PgE – Prostaglandins  SP - Substance P  Pain Fiber: *C fiber *A δ fiber
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  The purpose ofpain: protective mechanism  A signal of a disease.  Occurs whenever any tissue is being damaged.  Helps in detection, localization and identification of tissue damage.  Causes the individual to react to remove the pain stimulus.
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  Mechanism
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  Fast Pain: *Sharp/Prick/acute/electric pain. *Within millisecond. *Notfelt in the deeper tissues of the body. Types of Pain Slow Pain: *Burning/aching/throbbing/nauseating. *Can be excruciating. *Can occur in both skin and deeper tissues.
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  The non –pharmacological management involves the following approaches • Physiotherapy • Psychological techniques •Stimulation therapies – Acupuncture & Transcutaneous Electrical Nerve Stimulation (TENS) •Palliative care – involves the alleviation of symptoms but does not cure the disease.
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  Pharmacological medications  Non-Narcoticsor NSAIDs oral / local  Narcotics (IM, IV, SC, PCA intrathecal, epidural)  Local anesthetics (combination of local anesthetic & narcotics)  Psychotherapeutic approaches (Anxiolytic, biofeedback, relaxation).  Anticonvulsant therapy.
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  Evaluation of Analgesic effect Principle: Painis induced to a suitable animal and the response of the animal to the painful stimuli is recorded before and after administration of drugs. Analgesics drugs inhibit the perception (sensation) of the pain. Two types of acute pain Superficial- Fast response Deep - Slow response
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  Requirements • Animal: Mouseor Rat • Instrument: Hot Plate Analgesiometer • Painful Stimulus: Heat (550 C) • Drug used: Morphine 1-2 mg/kg, i.p Pentazocine 20mg/kg, i.p
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  Procedure 1. Weigh andmark the rats 2. Place the animals on the hot plate 3. Observe the basal reaction time (paw licking or jumping response)with a constant temperature (55 ͦ C) 4. Inject Morphine sulphate (5mg/kg), I.P 5. Note down the reaction period at different time intervals (30, 60 and 120 min) 6. Observations note down in the table
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  Procedure • In thismodel prior to the experiment the hot plate was set for a temperature 550 C. Weight animal and number the rat. Take the basal reaction time by observing hind paw licking or jump response (whichever appears 1st) in animal when placed on hot plate. Normally an animal shows such response in 6-8 seconds. • A cut off period of 15 sec is observed to avoid damage to paws. • Inject Pentazocine to the animals 30 minutes prior to the recording the response.
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  The time forlicking paws or jumping in hot plate was recorded as a response, prior and 0, 30, 60, 90, 120 min after administration of the drug. As the reaction time increased with Pentazocine, 15 seconds is taken as maximum analgesia and the animals are removed from the hot to avoid injury to the paws. • Calculate percentage increase in reaction time (as index of analgesia) at each time interval.
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  Observation Table S.No. Drug Treatmen tdose Time in (min) Basal reaction time (sec) Reaction time (sec) after drug administration Paw licking Jump response Paw licking Paw licking 1. Pentazocine 20mg/kg,ip 30 2 4 7 >10 2. 60 2 4 6 >10 3. 90 2 4 6 >10 4. 120 2 4 5 9 5.