Anaesthesia & Exodontia Third Year

1. Analgesics
Dr. Wael M. Talaat

2. Objectives



Knowledge of different types of analgesics
How to manage the side effects of these
analgesics
How to write a prescription

3. Topics to be discussed




Acetaminophen
Salicylates
Nonsteroidal anti-inflammatory agents
Opiates

4. Acetaminophen
Background

Common in OTC
products (Tylenol,
Paracetamol)

Found in combination
with other products

5. Acetaminophen
Pharmacokinetics




Rapidly absorbed from GI tract
Peak concentrations w/in 1-2 hrs (tabs)
10% bound to plasma proteins
Half-life is 2-3 hrs

In overdose can be 12 hours

6. Acetaminophen
Metabolism
Acetaminophen
5%
urine
80-90%
Glucuronic Acid
or sulfate
Non Toxic

7. Acetaminophen
Clinical Presentation (Stages)

Stage 1 (0-24 hours)
Often no symptoms
 Nausea, vomiting, anorexia may occur


8. Acetaminophen
Clinical Presentation (Stages)

Stage 2 (24-48 hours)


bilirubin , PT prolonged
Stage 3 (3-4 days)
Coagulation defects, jaundice, renal failure, hepatic
complications may be present
 Death is usually due to hepatic failure


9. Acetaminophen
Clinical Presentation (Stages)

Stage 4 (Recovery)

Liver returns to
normal within 3
months

10. Acetaminophen
Rumack-Matthew Nomogram
Acetaminophen (mcg/ml)
1000
Probable
toxicity
100
10
Toxicity
unlikely
1
4
8
12
18
Hours from ingestion
24

11. Acetaminophen
N-acetylcysteine cont.

Administration Overview
It comes in 10% and 20% solutions
 Must be diluted to a 5% solution prior to
administration


12. Acetaminophen
N-acetylcysteine cont

Oral Administration
Load: 140mg/kg
 Maintenance: 70mg/kg Q 4 hours X 17 doses
 If pt vomits w/in 1 hour, repeat dose and consider
increasing dilution


13. Acetaminophen
N-acetylcysteine cont

IV administration (not FDA approved)
Dilute 1:5, administer over 1 hour through 0.22
micron filter
 Load: 140mg/kg
 Maintenance: 70mg/kg Q 4 hours X 11 doses


14. Acetaminophen
Management cont.

Supportive care



Vitamin K considered if PT> 1.5X control
For extended relief product, repeat level 6-8
hours after ingestion
Hemoperfusion or hemodialysis have no
conventional role

15. Salicylates

Sources

Acetylsalicylic acid
(Aspirin)


Methyl salicylate


regular, buffered,
enteric coated
oil of wintergreen
Bismuth
subsalicylate

PeptoBismol

16. Salicylates
Pharmacokinetics





Absorbed rapidly
Peak of 2-5 hours
Highly protein bound
Mainly metabolized by conjugation in liver
Renal excretion

17. Salicylates
Dosing

Toxic dose
< 150mg/kg
 150-300mg/kg
 300-500mg/kg
 >500mg/kg

no symptoms expected
mild to mod. symptoms
serious symptoms
potentially lethal

18. Salicylates
Mechanisms of toxicity


Stimulates the CNS respiratory center
Alters glucose metabolism

19. Salicylates
Clinical Presentation

Respiratory


Electrolytes


Tachypnea, pulmonary edema
Sodium, potassium, and bicarbonate excretion
CNS

coma, seizures

20. Salicylates
Clinical Presentation

GI


CV


Nausea, vomiting
Hypotension, tachycardia
Other

Fever, glucose abnormalities, PT prolongation,
tinnitus

21. Salicylates
Treatment



ABC’s
Hemodialysis
Replace electrolytes

22. Salicylates
Hemodialysis Indications






Coma
Seizures
Pulmonary edema
Acute level >100mg/dl
Refractory acidosis
Renal failure

23. Nonsteroidal Anti-inflammatory
Agents

24. NSAID’s
Pharmacokinetics





In general, rapidly absorbed
Highly protein bound
Time to peak between 1-4 hours
Half-lives vary from 1-86 hours
Undergo hepatic metabolism and are mainly
renally eliminated (some thru feces also)

25. NSAID’s
Toxic dose

Generally, significant symptoms occur after the
ingestion of more than 5-10 times the usual
therapeutic dose

26. NSAID’s
Clinical presentation

GI


CNS


Nausea, vomiting, abdominal pain
Drowsiness, headache, tinnitus, dizziness, coma and
seizures (severe ingestions)
CV

Hypotension (severe ingestions), tachycardia

27. NSAID’s
Clinical presentation

Renal


Hematologic


Acute renal failure
Aplastic anemia, prolonged PT
Acid-Base

Metabolic acidosis is seen rarely (usually due to
seizures)

28. NSAID’s
Clinical presentation

In piroxicam and massive ibuprofen
overdoses….seizures, coma, renal failure, and
cardiorespiratory arrest may occur

29. NSAID’s
Treatment

Supportive care
Antacids may be used for GI upset
 Fluids if dehydrated


Hemodialysis may be effective for ketoprofen

30. Opiate/Opiod Toxicity

Opiates


Naturally occurring compounds
Opiods

Refers to derivatives and synthetic analogs

31. Opiate/Opiod Toxicity
Agents




Codeine, morphine, hydromorphone,
hydrocodone, oxycodone, levorphanol,
oxymorphone
Meperidine, diphenoxylate, fentanyl, alfentanil,
sufentanil, remifentanil
Methadone, propoxyphene
Pentazocine, butorphanol, nalbuphine

32. Opiates
Pharmacokinetics




Usually peak within 2-3 hours
Half-lives vary
First pass effect when adminstered orally
Variable rates of elimination

33. Opiate Toxicity
Clinical Presentation

CNS


Respiratory


Seizures (meperidine, propoxyphene), coma,
pinpoint pupils
Respiratory depression, apnea
GI

Decreased gut motility

34. Opiate Withdrawal






Anxiety, sweating
Abdominal cramps
Nausea, vomiting,
diarrhea
Insomnia, restlessness
Tachycardia
Yawning

35. Opiate Toxicity
Treatment



ABC’s
Supportive care
Antagonists
Naloxone
 Nalmefene


No way to enhance elimination

36. Opiate Toxicity
Naloxone


Administered via IV, IM, SC
Dose



0.4-2mg IV, repeated Q 2-3 minutes up to 10mg trial
Duration is 30min-2hrs
Asymptomatic for 3-4 hours since last dose
prior to discharge

37. Opiate Toxicity
Naloxone

Continuous infusion
To prevent resedation
 2/3rds initial reversal dose per hour administered IV
 1/2 initial reversal dose given as a bolus when
infusion started


38. Opiate Toxicity
Nalmefene (Revex®)


Administered IV, IM, or SC
Dose
0.5mg IV followed by
 1.0mg IV 2-5 minutes later if needed
 Unlikely any response if none by 1.5mg



Duration is 3-10 hours
Asymptomatic for 8-12 hours after last dose

39. Prescription

A written order or authorization directing a
pharmacist to furnish certain drugs to a patient

40. Writing the Prescription

Five Parts
Superscription
 Inscription
 Subscription
 Signa (Sig.)
 Signature


41. Writing the Prescription

Superscription

The patients name, address and symbol Rx (“take
thou”)

42. Inscription


The body of the prescription
Contains the official names and quantities of
drug prescribed

43. Subscription


The directions to the pharmacist
Indicates dosage form and quantities to be
dispensed

44. Signa (sig)

The instruction to the patient for use of the
preparation

45. Signature



The prescriber’s signature and professional
degree
DEA number for controlled substances
Refills

46. Some sample scenarios

During your history taking, the patient informs
you that he has been taking aspirin daily for the
last 2 years. Upon clinical examination, you find
3 badly decayed teeth indicated for extraction.
How would you manage this case ??

47. Some sample scenarios

A diabetic patient needs to extract his tooth. The
patient informs you that he has recently had a
prosthetic valve. How will you prepare this
patient for extraction ??

48. Some sample scenarios

Upon prescribing a NSAID postoperatively
following surgical extraction, you noticed that
the patient was suffering from a peptic ulcer.
How are you going to manage this case ??