Pharmacology

1. GENERAL ANESTHETICS
&
LOCAL ANESTHETICS
DR FOUZIA

2. GENERAL ANESTHESIA
General anesthesia is a state characterized by
1-Unconsciousness
2-Analgesia
3-Amnesia
4-Skeletal muscle relaxation
5-Loss of Reflexes

3. CLASSIFICATION OF GENERAL ANESTHETICS
1-Volatile Liquids:
Chloroform
Halothane
Enflurane
Isoflurane
Desflurane
Sevoflurane
2-Gases:
Nitrous oxide

4. CLASSIFICATION OF GENERAL ANESTHETICS
Intravenous anesthetics:
Barbiturates
Thiopentone
Benzodiazepines
Midazolam, Diazepam
Opioid analgesics
Morphine, Fentanyl
Others
Propofol
Ketamine
Droperidol

5. INHALED ANESTHETICS
MAC:
It is the potency of inhaled anesthetics
It is defined as:
“ the concentration of inhaled anesthetic needed to eliminate movement in
50% of patients exposed to a noxious stimuli”
It is expressed as the percentage of gas in a mixture to achieve that effect.
MAC value is small for potent anesthetics (Desflurane 2%)
MAC value is large for less potent anesthetics (Nitrous oxide 105%)

6. PHARMACOLOGICAL EFFECTS OF INHALED
ANESTHETICS
1-CNS:
Vasodilation ↑ cerebral blood flow↑ intracranial pressure.
Enflurane cause seizures, NO cause analgesia and amnesia
2-CVS:
↓BP and cardiac out put
3-Respiratory system:
Bronchodilation
↓ mucociliary function in the airway
4-Uterus:
Relaxation (Intrauterine fetal manipulation or manual extraction of a retained
placenta )

7. ADVERSE EFFECTS OF INHALED ANESTHETICS
1-Cardiac effects:
Bradycardia, arrhythmias
2- Nephrotoxicity
Enflurane and sevoflurane
3-Hematotoxicity
NO  Megaloblastic Anemia
4-Hepatotoxicity
Halothane
5-Malignant hyperthermia:
Exposure to halothane or succinylcholine
Treatment: Dentrolene, Cooling blankets, Maintain respiration, acid base balance

8. INTRAVENOUS ANESTHETICS
Barbiturates
Thiopentone
Benzodiazepines
Midazolam, Diazepam
Opioid analgesics
Morphine, Fentanyl
Others
Propofol
Ketamine
Droperidol

9. THIOPENTAL
Ultra short acting Barbiturate
Clinical uses:
1-Induction (less than 30sec)
Adverse effects:
1-Intra-arterial injection :
Pain, vasoconstriction & gangrene.
2-Respiratory depression
3-Bronchospasm
4-↓BP

10. PROPOFOL
Clinical uses:
1-Induction and maintenance
2-Total I/V anesthesia with opioids
3-Sedation of patients in ICU
4-Short procedures (endoscopy, colonoscopy)
5-Low dose for postoperative nausea and vomiting
Adverse effects:
1-Severe hypotension
2-Respiratory depression
3-Pain at injection site

11. KETAMINE
I/V, I/M, oral, rectal, epidural routes
Clinical uses:
1- Dissociative anesthesia:
Patient is unconscious but appear to be awake with profound analgesia
2- Short surgical procedures (Analgesia)
3-I/V anesthetic of choice in
A-Children & Old persons
B-Septic shock, Cardiogenic shock, Bleeding
D- COPD
4-Arthritic pain (Topical)

12. ADVERSE EFFECTS OF KETAMINE
1-Emergence delirium
During recovery  hallucinations, illusions and dream like state (24 hrs)
2-I/V injection  necrosis, thrombophlebitis, nerve damage
3-↑ Intraocular pressure
4-↑ Intracranial pressure
5-↑ Blood pressure
6-↑ Heart rate
8- Contraindicated in head injuries

13. PREANESTHETIC MEDICATIONS
1-BZD:
↓Anxiety : Diazepam, Lorazepam, Midazolam
2-Opioids:
Analgesia : Morphine, Pethidine , Fentanyl
3- Antiemetics
↑ gastric emptying : Metoclopramide, Ondansetron
4-Anti-histamines
↓Anxiety , Antiemetic and Anticholinergic Properties : Promethazine
5-Anticholinergics
↓Salivary and bronchial secretions: Atropine, hyoscine
6-Proton pump inhibitors/ H2 blockers
↓ gastric acid ,↓ regurgitation : Omeprazole ,Pantoprazole/ Ranitidine ,Famotidine

14. LOCAL ANESTHETICS
“Produce reversible inhibition of impulses in nervous tissues when applied locally”
Classification of local anesthetics:
A-Esters:
Procaine
Cocaine
Tetracaine
Benzocaine
A-Amides
Lignocaine /Lidocaine
Bupivacaine
Ropivacaine
Articaine

15. LOCAL ANESTHETICS
Mechanism of action:
1-Block nerve conduction of sensory impulses
2-Na+ channels are blocked to prevent the action potential
3-Sensation cannot be transmitted from site of stimulation to brain

16. THERAPEUTIC INDICATIONS OF LOCAL ANESTHESIA
1-Surface anesthesia
2-Infiltration anesthesia & field block anesthesia
3-Nerve block anesthesia
4-Spinal anesthesia
5-Epidural anesthesia
6-Used in ophthalmology
7-Used in dentistry

17. ADVERSE EFFECTS OF LOCAL ANESTHETICS
1-CNS effects:
Light headedness
Restlessness
Sleepiness
Auditory/visual disturbance
Metallic taste
Tongue numbness

18. ADVERSE EFFECTS OF LOCAL ANESTHETICS
1-CNS effects:
Muscle twitching
Nystagmus
Tonic clonic convulsions
2- CVS effects:
Vasodilatation  Hypotensive effects
Cardiac arrhythmia
3-Local injury:
Neural injury