Department of Pharmacy
Daffodil International University
Anesthetic is a drug that temporarily depresses
neuronal function producing total or partial loss of
sensation with or without the loss of consciousness.
A drug that causes a person to lose feeling and to
feel no pain in part or all of the body.
Anesthetic mainly categorized into two classes-
Local anesthetics are agents that prevent
transmission of nerve impulses without causing
They are used mainly in-
It should not be irritating to the tissue.
Its systemic toxicity should be low because it is
eventually absorbed from its site of application.
The time for onset of action must be short as
The duration of action must be sufficient to
allow time for the surgery
It should be effective in body pH.
The time should not be so long for an extended
period of surgery.
Mechanism of action
Local anesthetic bind with the protein of Na+
Block the Na+conductance
Block the depolarization, fails to initiation and
propagation of action potential
Afferent impulse cannot go to the higher center
No pain sensation
There are two types of local anesthetic-
Ester local anesthetic:
The local adverse effects of anesthetic agents include
neurovascular manifestations such as prolonged anesthesia
and parasthesia(tingling, feeling of "pins and needles", or
strange sensations). These are symptoms of localized nerve
impairment or nerve damage.
General systemic adverse effects are due to the
pharmacological effects of the anesthetic agents used. The
conduction of electric impulses follows a similar
mechanism in peripheral nerves, the central nervous
system and the heart. The effects of local anesthetics are
therefore not specific for the signal conduction in
peripheral nerves. Side effects on the central nervous
system and the heart may be severe and potentially
A general anesthetic is a drug that has the ability to bring
about a reversible loss of consciousness.
Induce anesthesia smoothly and rapidly.
They must cause amnesia.
Ensure rapid recovery from its effect.
Be non-irritant, non-inflammatory.
They must have analgesic property.
Administration by simple apparatus.
Avoid adverse effect.
They are classified into three group-
Mechanism of action
General anesthesia works by altering the flow of sodium
molecules into nerve cells through the cell membrane. Exactly
how the anesthetic does this is not understood since the drug
apparently does not bind to any receptor on the cell surface
and does not seem to affect the release of chemicals that
transmit nerve impulses from the nerve cells. It is known,
however, that when the sodium molecules do not get into the
neurons, nerve impulses are not generated and the brain
becomes unconscious, does not store memories, does not
register pain impulses from other areas of the body, and does
not control involuntary reflexes. Although anesthesia may feel
like deep sleep, it is not the same. In sleep, some parts of the
brain speed up while others slow down. Under anesthesia, the
loss of consciousness is more widespread.
Actual theories are based on: