AnalgesicsAnalgesicsAnalgesicsAnalgesics

Chapter 26Chapter 26Chapter 26Chapter 26

Types of Pain (acute, chronic)

Deep

Somatic

Superficial

Skin

Pin prickpinchingscraping

Conn.tissuesBonesJointsMuscles

ArthritisMuscle cramps/Bone fractures

Visceral

Kidney stonesGastric torsionIntussuceptionsColic etc.

Neuropathic

Therapeutic Management of Pain

IrritantsHeatingCoolingLotionsRadiations

Drugs AcupunctureElectro-acupuncture

NerveBlocks

NarcoticsOpiates

Non-NarcoticsNSAIDs

Opium 阿片 Poppy PlantPoppy Plant (Papaver somniferum (Papaver somniferum 罂粟罂粟 ))

– Cultivated in:Cultivated in:• Middle East (Afghanistan and Pakistan)Middle East (Afghanistan and Pakistan)• ThailandThailand• South America and MexicoSouth America and Mexico

Incision of the poppy seed pod reveals a Incision of the poppy seed pod reveals a substance that turns into a brown gum that substance that turns into a brown gum that is crude opium.is crude opium.

阿片生物碱类

镇痛镇痛药 药 阿片生物碱类阿片生物碱类

Fresh capsule of opium poppy

Cut capsule showing latex exuding from cut

Morphine Morphine 吗啡吗啡Actions

CNS : analgesia 镇痛作用 chronic continuous dull pain superior to acute

discontinuous sharp pain relief of pain without the loss of consciousness accompanied with sedation and euphoria 欣快 easy to fall asleep

respiration depression 抑制呼吸

reducing the sensitivity of respiratory center to COreducing the sensitivity of respiratory center to CO22

the most common cause of death in acute overdose the most common cause of death in acute overdose

depression of cough reflex 镇咳 Stimulate some certain parts of cerebra

miosis 缩瞳 ‘ ‘ pin-point pupils’pin-point pupils’

nausea and vomiting

Peripheral effects ： Gastrointestinal tract decreasing motility of smooth muscle and increasing tone

inhibiting gastric secretion

inhibiting center and leading to dull in awareness

of defecation 便意迟钝 constipation 便秘 Biliary tract

sphincter of oddi constrict biliary colic 胆绞痛 Uterus prolong labor

Renal urinary retention 尿潴留 sphincter of urinary bladder tension ↑ cardiovascular system

postural hypotension 体位性低血压 vasodilatation 血管舒张 the release of histamine

cerebral vessels dilatation and CSF pressure increase

respiratory depression and CO2 retention

Immune system:

Both cell immunity and humoral immunity are inhibited

Opioid Receptors

• μ= analgesia, respiratory depression ,

euphoria , dependence ,immunity inhibiton

• κ= analgesia , dysphoria 烦躁不安 , mania,

miosis 瞳孔缩小

• δ= analgesia

• σ

morphine decreases the release of substance P

Therapeutic uses of morphine analgesia 镇痛 : various cause of pains

especially when other analgesics are ineffective

biliary colic 胆绞痛 , renal colic 肾绞痛 + M ( － )

cardiac asthma 心源性哮喘sedation 镇静 镇静 and euphoria 欣快欣快 , removing tension

reducing the sensitivity of respiratory center to COreducing the sensitivity of respiratory center to CO22

dilating blood vessels, mitigating heart burdendilating blood vessels, mitigating heart burden cough codeine ( 可待因 ) diarrhea

Adverse effects nausea and vomitting, constipation, pressure increase

in the biliary tract tolerance and physical dependence

withdrawal syndrome 戒断综合征 acute poisoning

respiratory depression , pin-point pupilspin-point pupils

antagonizer － naloxone 纳洛酮

Contraindication of morphine

relieving expulsive pain, breast feeding women, newborn, relieving expulsive pain, breast feeding women, newborn, br

onchial asthma, , craniocerebral trauma 颅脑外伤者颅脑外伤者

不良反应不良反应 反复应用引起成瘾！反复应用引起成瘾！

SYMPTOMS OF WITHDRAWAL

Picture from: www.schoolscience.co.uk/.../4/ biology/medicines/drugs4.html

Synthesized analgesics

Pethidine 哌替啶 (dolantin, 度冷丁 ) Actionsmainlyactivate receptor

Therapeutic uses substitute of morphine analgesia 镇痛

the same analgesic effect as morphine cardiac asthma 心源性哮喘 pre-anesthesia medication and artificial hibernati

on

physical dependence!

fentanyl 芬太尼• mainly activate receptor

• 80 times the analgesic potency of morphine

• used as preoperative medication

• rapid onset and short duration of action

(15 to 30 minutes)

• combined with droperidol combined with droperidol 氟哌利多→氟哌利多→neurolepticanalgesia neurolepticanalgesia 神经松弛镇痛神经松弛镇痛

pentazocine 喷他佐辛 an agonist on κ and a partial agonist at μ receptors producing less euphoria 欣快 than morphine high doses increase blood pressure and can cause h

allucinations 幻觉 , tachycardia and dizziness mainly used in chronic pains belonging to nonrestrictive analgesics

rotundine 罗通定mainly used in chronic dull pain 慢性钝痛 and visceral

gia 内脏痛no addiction 成瘾性

Opioid receptor antagonist

naloxone 纳洛酮纳洛酮 , naltrexonenaltrexone 纳曲酮纳曲酮 competitive μ,μ, κκreceptors receptors antagonists

rapidly reversing respiratory depression and blood pres

sure fall of opioid overdose

used in emergency treatment of opioid overdose