Local anesthetic & general anesthetic

Presented by:Samya SayantanId: 121-29-381Batch: 7th

Sec: ADepartment of PharmacyDaffodil International University

Anesthetic: 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 anesthetic General anesthetic

Local anestheticLocal anesthetics are agents that prevent

transmission of nerve impulses without causing unconsciousness.

They are used mainly in- Minor surgery Dentistry Ophthalmology Acute pain Chronic pain

Properties

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 possible

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+

channel 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

Types There are two types of local anesthetic- Ester local anesthetic: Procaine Cocaine Tetracaine Benzocaine Propoxycaine Cyclomethycaine Proparacaine Chloroprocaine

Amide local anesthetic: Lidocaine Prilocain Mepivacaine Etidocaine Bupivacaine Ropivacaine Artcaine Levobupicaine Trimecaine

Adverse effect 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 fatal.

 

General anesthesiaA general anesthetic is a drug that has the ability

to bring about a reversible loss of consciousness.

Properties 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.

Classification

They are classified into three group- Pre-anesthetic: Anticholinergic Anti histamine Barbiturates Benzodiazepine Opioids

Intravenous: Barbiturates Benzodiazepine Ketamine Propofol Opioids

Inhalational: Desflurane Enflurane Halothane Isoflurane Nitrous oxide

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: Lipid theory Ion channel

Adverse effect Pain Nausea and vomiting Damage to teeth Sore throat and laryngeal damage Respiratory depression Hypoxic brain damage Nerve injury Headache