The document defines various terms related to analgesics including opioids and non-opioid analgesics. It describes opioids as originating from the opium poppy and acting primarily through mu receptors to powerfully relieve pain. It notes opioids can cause tolerance, dependence, and withdrawal symptoms. Non-opioid analgesics like paracetamol and NSAIDs inhibit prostaglandin synthesis to reduce pain and fever without dependence. The document provides details on specific opioid and non-opioid analgesic drugs, their uses, mechanisms, and side effects.

1. ANALGESICS

2. Introduction
TERMINOLOGIES
Analgesic: A drug that selectively relieves pain by acting
in the CNS or on peripheral pain mechanism, without
significantly altering consciousness.
Analgesia: refers to absence of pain without the loss of
consciousness.
Narcotics: they are analgesic, CNS depressant, and any
drug capable of causing physical dependence.
Opioid: is any drug natural, semi synthetic or synthetic
that has actions similar to those of morphine.

3. Definitions continued
Opiates- refers to any compound present in
Opium-(alkaloids derived from opium) e.g
morphine, codeine, heroin and opium.
Pain- is any unpleasant sensation ranging from
mild discomfort to organized distress caused by
disease, injury, or emotional sufferings that hurts
the body.

4. Definition continued
 Pain can be classified as;
 (a) Acute- it is usually associated with trauma or
disease and has a well defined location, character
and timing. It is accompanied by symptoms such
tachycardia, hypertension, sweating and
mydriasis.
 (b) Chronic- this is pain lasting more than a few
months. It may not be associated with disease or
trauma or may persist after initial injury has
healed. Location, character and timing are more
vague in chronic than in acute pain.

5. Opioid Analgesics
 Originate from the opium poppy (plant).
 Powerful pain relievers.
 Opioid analgesics are the most effective
analgesics and are used in the management of
severe pain.
 They are divided into two: weak opioid analgesics
e.g. codeine, dihydrocodeine and strong opioid
analgesics such as morphine pethidine,
methadone.

6. Classified according to their chemical
structure and action
 Morphine-like derivatives (codeine, morphine,
oxycodone, hydromorphone, oxymorphone).
 Pethidine/meperidine-like derivatives (fentanyl,
pethidine)
 Methadone-like derivatives (methadone)
 Other: tramadol 50 to 100 mg 4 hrly (no risk of
physical addiction – inhibits reuptake of serotonin
and norepinephrine)

7. Opioid receptors
Three main classes of opioid receptors, designated
as mu, kappa, and delta.
From the pharmacologic perspective, mu receptors
are the most important. This is because opioid
analgesics act primarily through activation of mu
receptors, although they also produce weak
activation of kappa receptors.
As a rule, opioid analgesics do not interact with
delta receptors. In contrast to opioid analgesics,
endogenous opioid peptides act through all the
types of opioid receptors.

8. Mechanism of action
Stimulate opiate receptors in the brain.
They relieve pain by mimicking the action of
endogenous opioid peptides, primarily at mu
receptors.

9. Opioid analgesics
 Repeated administration may cause tolerance
(patient needs increasing dose of drug to get
same analgesic effect) or psychological or physical
dependence.
 Withdrawal signs: restless, sweating, runny eyes,
runny nose, dilated pupils, can develop into
muscle spasms, muscle cramps, insomnia, N, V, D,
inc temp, inc BP, inc HR and RR
 Withdrawal symptoms reach peak at 36-72hrs after
stopping the drug and disappear over the next 5 to 14
days.

10. Opioids: Uses
 Opioids used to control moderate to severe pain
particularly of visceral origin.
 Used for pain control after surgical operation.
 Codeine Phosphate 30mg tab also used as cough
suppressant.
 Morphine Sulphate is used most widely.
 Tramadol Hcl is not as effective in severe pain as
other opioid analgesics.

11. Opioids: Side effects
 The most common include nausea, vomiting,
constipation, drowsiness, sedation, confusion,
euphoria, urinary retention.
 Larger doses produce respiratory depression and
hypotension.
 Convulsions and worsening of asthma may occur.
 Tolerance and physical dependence may occur.
 Drowsiness affects performance of skilled labour and
it is increased by presence of alcohol.

12. Opioids: Contraindications
 Known medicine allergy.
 Severe asthma.
 Used with caution in:
– Patients with severe head injuries (mask level of
consciousness).
– Morbid obesity with respiratory disturbances
when asleep (apnoea).
– Bowel paralysis – opioids tend to slow bowel
movements and can cause constipation.

13. 13
Opioids
Medicine Formulation Dosage
Adult Child
Morphine
Sulphate
Tablet 10mg 5 – 20mg (or more)
every four hours
(chronic pain)
2.5-5mg every four
hrs prn
10mg/30mg/60mg
(Slow release)
Daily dose in two
divided doses
Adjusted as needed
Inj 10mg in 1ml amp 10mg every 4hrs
(acute pain)
Syrup 10 mg / 5 ml Adjusted as needed 2.5-5mg as needed
Dyhydrocodeine
(DF118)
Tab: 15 mg ,30 mg
(phosphate).
15-30mg every four
hours
0.5-1mg/kg every
four hours.

14. Opioids: Toxicity
 When used in overdose, opioids are toxic.
Signs and symptoms:
Coma
Respiratory depression
Pinpoint pupils
 Antidote used is Naloxone.
 It acts by blocking the effects of opioids including CNS
and respiratory depression.
 Therapeutic outcome is reversal of signs of opioid toxic
effects.

15. Antidote: Naloxone
 Dosage form 400mcg/ml injection
 Dose: IV injection, ADULT: 0.4-2mg repeated
at intervals of 2-3 minutes up to a maximum
of 10mg. CHILD: 10mcg/kg, subsequent dose
of 100mcg/kg if no response.

16. Points to note
 Opioids are controlled medicines and should
only be supplied on prescription by qualified
medical practitioner.
 Prescribing of these medicines are subject to
legal requirements.
 Strict legal requirements require detailed
recording of dispensing and issue of these
medicines.

17. Points to note
 Drug intxn: other CNS depressants i.e. Alcohol,
antihistamines, antidepressants (TCAs)
 If someone is on chronic pain treatment with opiates,
need to also be on drugs for prophylaxis of constipation.
Start opiate and the drug for constipation at the same
time i.e. Can use a stool softener (docusate
calcium/sodium) PLUS bisacodyl daily
 Patient can develop tolerance to nausea side effect of
opiates, but will NEVER develop tolerance to
constipation, therefore need to PREVENT constipation
when starting chronic opiate use

18. Morphine sulphate
 Indications - severe pain, pulmonary oedema, and pain
associated with heart attack, during major surgery and
postoperative analgesia, Myocardial infarction, Sickle cell
crisis, Chronic pain(cancer).
 Contraindication: Acute respiratory depression, Known
hypersensitivity to morphine, Acute alcoholism, Head
injury
 Dose – 10mg initially, reduce to 5mg in the elderly;
children 100mcg/kg
 Adverse Reactions- severe respiratory depression,
constipation.

19. Codeine/dihydrocodeine
 Uses - allergy, cold and cough remedies, antitussives,
opioid analgesics
 Side Effects - confusion, sedation, hypotension,
constipation.
 Contra-indications: Respiratory depression,
Obstructive airway disease, Hypersensivity to codeine,
Acute alcoholism, Raised intracranial pressure or head
injury, Risk of paralytic ileus
 Usually supplied in combination with other analgesics
 Dosing: 10-60mg every four hours.

20. PETHIDINE
 Indications: Pre-operative medication, Acute
analgesia, Post-operative, Moderate to severe
acute pain, Obstetric analgesia.
Contra indications: Severe renal impairment,
Acute respiratory depression, acute alcoholism,
Head injury, Severe liver disease, Avoid injection in
phaeochromacytoma, Known hypersensitivity to
pethidine.
 Side effects: Confusion, Spasm of urinary tract.

21. TRAMADOL
MOA: It inhibits reuptake of noradrenalin and 5HT,
and thus activates monoaminergics spinal inhibition
of pain.
Indications: Moderate to severe pain,
Postoperative pain, Neuropathic pain, Cancer pain,
Low back pain,Pain associated with orthopedic
disorders.
Contraindications: known hypersensitivity to
tramadol, Acute intoxication with alcohol,Severe
renal impairment

22. TRAMADOL
 Side effects: Weakness, Fatigue, Diarrhea,
Headache, Hypotension, Sweating, Constipation,
Dizziness, Hallucination, Nausea and vomiting,
Dry mouth, Urticaria.
Precautions
Avoid rapid IV injection since it associated with a
higher incidence of side effects
Inform a patient that tramadol causes dizziness and
drowsiness which may impair the ability to perform
activity require mental alertness
Avoid alcohol and other medications that cause
sedation

23. NONNARCOTIC ANALGESICS

24. INTRODUUCTION
• They do not depress CNS
• They do not produce physical dependency
• Have no abuse liability and weaker analgesics
• Most of these drugs can produce three clinical effects:
suppression of inflammation; relieve of pain and reduction of
fever.
Mechanism of action
Inhibition of cyclooxygenase, an enzyme require for the
biosynthesis of prostaglandins and related metabolites of
arachidonic acid (prostacyclin and thromboxane A2)

25. Non-Opioid analgesics
 Paracetamol/Acetaminophen.
 Salicylates (Anti-inflammatory medicine)-
acetylsalicylic acid (Aspirin) prototype for class.
 Non-Steroidal Anti-Inflammatory medicines
(NSAIDS) e.g. Ibuprofen, diclofenac sodium,
naproxen sodium, aceclofenac.
 All these substances also reduce fever.

26. Paracetamol/Acetaminophen
 Action: Blocks central pain impulses (cyclo-oxygenase 3
inhibitor).
 Note: Acetaminophen does not block the prostaglandin synthesis
in the peripheral tissues but instead produces pain relief through
central mechanisms.
 Uses: Treatment of mild to moderate pain, to lower elevated
body temperature., Treatment of Gout i.e.
Aetaminophen+probenicid.
 Contraindications: Medicine allergy, liver disease.
 Cautions: Hepatic impairment, renal impairment, alcohol
dependence.
 Side effects: Rare, but rashes, blood disorders, liver damage.
 Dose: By mouth, 0.5–1 g every 4–6 hours to a max. of 4 g daily.

27. Paracetamol: Toxicity
 Ingestion of large amounts of paracetamol, as
in acute overdose, or even chronic
unintentional misuse can cause liver damage.
 Acute ingestion of doses of 150 mg/kg or
more may result in severe hepatic toxicity,
dizziness and disorientation.
Treatment: Liver damage is minimized by
administering Acetylcysteine (Mucomyst)

28.  Action: Aspirin provide analgesia by blocking prostaglandins
synthesis, that sensitize the peripheral pain receptors to
send a pain signal to the central nervous system (CNS). i.e.
Non-selective cyclo-oxygenase inhibitor.
 Use: Mild to moderate pain including dysmenorrhoea,
headache, acute migraine attack and pyrexia (fever). It
prevents platelets aggregation (Thromboembolic disorders,
Prophylaxis in myocardial infarction).
 Cautions: Asthma, allergic disease.
 Contra-indications: Children and adolescents under 16
years and in breast-feeding, previous or active peptic
ulceration, haemophilia, Pregnancy, gout.
Acetysalicylic acid (ASPIRIN)

29. Acetysalicylic acid
• Dose: by mouth 300-900mg every 4-6 hours when
necessary. Maximum dose 4g per day.
• Side effects:
– GI ulceration: Gastric acidity  GI protection
–  Bleeding.
–  Renal elimination.
–  Uterine contractions during labour.

30. Reyes Syndrome
 The acetic class of medicines e.g. aspirin is
contraindicated in children.
 It is associated with Reyes syndrome - a fatal
disease affecting many organs especially the
brain and liver.
 Symptoms include vomiting and rashes.
 Manage fever in children with paracetamol and
not with acetylsalicylic acid.

31. Diclofenac sodium
• Use: Anti-inflammatory, analgesic, and antipyretic.
Treatment of Acute gout, Rheumatoid arthritis, Migraine,
Renal colic pain, Tendonitis, Strains and sprain, Post
operative pain.
• Cautions: Asthma, allergic disease.
• Contra-indications: Children and adolescents under 16
years and in breast-feeding, previous or active peptic
ulceration.
• Dose:
– By mouth, 25–100 mg every 8 -12 hours when necessary; max.
100mg daily.
– IM 75mg daily.

32. Ibuprofen
 Use: anti-inflammatory, analgesic, and antipyretic.
Used in treatment of gout.

 Cautions: asthma, allergic disease.
 Contra-indications: children and adolescents under 16
years and in breast-feeding, previous or active peptic
ulceration and pregnancy.
 Dose: By mouth,400mg three times daily max 1.8 g
daily. doses preferably after food; increased if
necessary to max. 2.4 g daily.

33. Indomethacin
Indications
Treatment of rheumatoid arthritis, osteoarthritis,
tendonitis
Contraindications
Cardiac dysfunction, Hypertension, Decreased
renal/hepatic function, Epilepsy, Concurrent
anticoagulant therapy.
 Adverse effects
Severe frontal headache, Dizziness, Vertigo,
Confusion

34. END