USES OF OPIOIDS IN ANAESTHESIA
 Mainly used for analgesia ,for both intra-operative &
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postoperative.
As a premedicant.
As an inducing agent ( rarely used as it requires very high
doses).
Blunting cardiovascular response to intubation. Fentanyl is
the most commonly used but sufentanil is the agent of
choice.
For day care surgery (Propofol + Alfentanil is the
combination of choice.
For painless labor ( Fentanyl + Bupivacaine by epidural route.
Pulmonary edema ( Morphine is the agent of choice).
Intra-operative myocardial ischemia ( Morphine is used ).
To abolish shivering ( Pethidine & Tramadol ).
Description
 Morphine, the most important alkaloid of opium, is
classified pharmacologically as a narcotic analgesic. a
white crystalline powder, soluble in water.
 It comes as a generic name – Morphine sulphate.
 Morphine can be given by IV, IM, subcutaneous, oral ,
rectal , transcutaneous ,intrathecal & epidural routes.
 Dose : 0.1- 0.2 mg /kg
Mechanism of action
 Mechanism of action is similar as other opioid drugs as
Meperidine.
 Morphine interacts predominantly with the μreceptor.
 Morphine produces respiratory depression by direct
action on brain stem respiratory centers.
 Morphine depresses the cough reflex by direct effect
on the cough center in the medulla.
 Morphine causes miosis.
Other effects
 Gastric, biliary, and pancreatic secretions are
decreased by morphine.
 Morphine can cause a marked increase in biliary tract
pressure as a result of spasm of sphincter of Oddi.
 Morphine produces peripheral vasodilation which may
result in orthostatic hypotension.
Indications and Usage
 Used in treatment of moderate to severe pain relief.
 Used in cancer related severe pain.
Side effects
 They include the following major hazards: respiratory
depression, apnea, and to a lesser degree, circulatory
depression, respiratory arrest, shock, and cardiac
arrest.
 Constipation, lightheadedness, dizziness, sedation,
nausea, vomiting, sweating, dysphoria, and euphoria.
 Urine retention or hesitance, reduced libido and/or
potency.
 Pruritus, urticaria
 Convulsions
Contraindication and Precautions
 In patients with known hypersensitivity to the drug.
 In patients with respiratory depression in the absence
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of resuscitative equipment, and in patients with acute
or severe bronchial asthma.
Head Injury and Increased Intracranial Pressure.
Severe Hypotensive patients.
Should be used in pregnant women only when clearly
needed.
Is not recommended for use in women during and
immediately prior to labor.
 Not used in Breast feeding mothers.
 Use of morphine has not been evaluated systematically
in children.
Overdosage
 Overdosage of morphine is characterized by respiratory
depression. Since respiratory arrest may result either
through direct depression of the respiratory center, or as
the result of hypoxia, primary attention should be given to
the establishment of adequate respiratory exchange
through provision of a patent airway and institution of
assisted, or controlled, ventilation.
 The narcotic antagonist, naloxone, is a specific antidote. An
initial dose of 0.4 mg of naloxone should be administered
intravenously, simultaneously with respiratory
resuscitation.
 Naloxone may be repeated at 2 to 3 minute intervals.
Meperidine (PETHIDINE)
 Meperidine hydrochloride is ethyl 1-methyl-4-
phenylisonipecotate hydrochloride, a white crystalline
substance with a melting point of 186°C to 189°C. It is
readily soluble in water and a slightly bitter taste. The
solution is not decomposed by a short period of
boiling.
 In foreign countries, it is known as pethidine.
Meperidine is not a natural opiate like morphine or
codeine, but is a synthetic compound belonging to the
phenylpiperidine class.
 Meperidine is recommended for relief of moderate to
severe pain but also has the unique ability to interrupt
postoperative shivering and shaking chills
Mechanism of action
 Despite being structurally distinct from morphine and
related opiates, meperidine's effects on opiate
receptors are similar to those of morphine; both are
agonists at mu and kappa receptors. Although the
exact physiologic action of opiates is not known,
stimulation of opiate receptors ultimately reduces
neurotransmitter release. This effect depends on –the
receptor it binds,the binding affinity ,and whether the
receptor is activated.
 Cellular mechanism- alterations in Potassium and
calcium condutance.
 Respiration is depressed by a direct effect on the brain stem
respiratory center, and the cough center is also suppressed
by meperidine.
 Nausea and vomiting may be induced from direct
stimulation of the chemoreceptor trigger zone. Opiate
agonists increase smooth muscle tone, which can affect the
intestinal, urinary, and biliary tracts. Digestion is delayed
by a decrease in gastrointestinal secretions. Some
references state that meperidine causes less biliary tract
spasm than does morphine. Vasopressin output is
stimulated, which can decrease urine output in
conjunction with increased tone of the detrusor muscle.
 Miosis is another characteristic of the opioid analgesics.
Compared with morphine, meperidine causes fewer of
these effects.
INDICATIONS AND USAGE
 Management of acute pain episodes of moderate to
severe in nature.
 Treatment of Post anesthesia shiverings.
Dosage and routes
 When changing route of administration, note that oral
doses are about half as effective as parenteral dose.
Oral route not recommended for chronic pain.
 Oral: Initial: 50 mg every 3-4 hours as needed; usual
dosage range: 50-150 mg every 2-4 hours as needed
 I.M. : Initial: 50-75 mg every 3-4 hours as needed;
patients with prior opiate exposure may require higher
initial doses; usual dosage range: 50-150 mg every 2-4
hours as needed
 Preoperatively: 50-100 mg given 30-90 minutes before
the beginning of anesthesia
 Slow I.V.: Initial: 5-10 mg every 5 minutes as needed
ADVERSE REACTIONS
 The major hazards of meperidine, as with other
narcotic analgesics, are respiratory depression and, to a
lesser degree, circulatory depression; shock, and
cardiac arrest have occurred.
 The most frequently observed adverse reactions
include : Dizziness, sedation, nausea, vomiting, and
sweating.
Other adverse reactions include:
 Nervous System: Euphoria, dysphoria, weakness,
headache, agitation, tremor, uncoordinated muscle
movements (e.g. muscle twitches, myoclonus), severe
convulsions, hallucinations and disorientation, visual
disturbances.
Gastrointestinal: Dry mouth, constipation, biliary tract
spasm.
Cardiovascular: Flushing of the face, tachycardia or
bradycardia, palpitation, hypotension ,syncope.
Genitourinary: Urinary retention.
Allergic: Pruritus, urticaria, other skin rashes, wheal and
flare over the vein with intravenous injection.
CONTRAINDICATIONS/PRECAUTIONS
 Meperidine should be used cautiously in patients with pulmonary
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depression or pulmonary disease such as acute bronchial asthma or
upper airway obstruction.
Patients with head trauma or with increased intracranial pressure
Patients with cardiac disease or hypotension.(vasovagal syncope or
orthostatic hypotension)
Meperidine should be used with caution in patients with
glaucoma(Increase IOP)
Pethidine is absolutely contraindicated in patients on monoamine
oxidase inhibitors therapy. Severe excitatory responses like restlessness,
hypertension,convulsion, coma & death can occur.
It should not be given to patients with myocardial ischemia as it
depresses the myocardium & by causing tachycardia increases the
oxygen demand.
 Meperidine should be prescribed extremely cautiously,
if at all, to patients with renal disease.
 patients undergoing biliary tract surgery, although
meperidine reportedly causes less biliary tract spasm
than does morphine.
 Meperidine readily crosses the placenta and normally
should not be given during pregnancy.
OVERDOSAGE
 Primary attention should be given to the reestablishment
of adequate respiratory exchange through provision of a
patent airway and institution of assisted or controlled
ventilation.
 The narcotic antagonist, naloxone hydrochloride, is a
specific antidote against respiratory depression which may
result from overdosage or unusual sensitivity to narcotics,
including meperidine. Therefore, an appropriate dose of
this antagonist should be administered, preferably by the
intravenous route, simultaneously with efforts at
respiratory resuscitation.
 Oxygen, intravenous fluids, vasopressors, and other
supportive measures should be employed as indicated.