NEET MDS Lessons
Pharmacology
PHARMACOLOGY OF LOCAL ANESTHETICS
Characteristics
1. Block axon conduction (nerve impulse) when applied locally in appropriate concentrations.
2. Local anesthetic action must be completely reversible; however, the duration of the anesthetic block should be of sufficient length to allow completion of the planned treatment.
3. Produce minimal local toxic effects such as nerve and muscle damage as well as minimal systemic toxic effects of organ systems such as the cardiovascular and central nervous system.
Griseofulvin
- Griseofulvin is an antifungal drug. It is used both in animals and in humans, to treat ringworm infections of the skin and nails. It is derived from the mold Penicillium griseofulvum.
- It is administered orally.
Hydromorphone
- About 8-10 times more potent than morphine when given intravenously.
- Slightly shorter duration of action.
- More soluble than morphine, thus higher concentrations may be injected if necessary.
- Better oral/parenteral absorption ratio than morphine, but not as good as codeine or oxycodone.
- It is used for the treatment of moderate to severe pain
Fluconazole: an antifungal used orally, intravenously or vaginally to treat yeast and fungal infections. Side-effects of systemic administration include hepatotoxicity (liver damage).
- For vaginal candidiasis (vaginal thrush), a once-only oral dose is often sufficient.
GENERAL ANESTHETICS
General anesthesia often involves more than one drug to get different, favourable effects.
Premedication is often used to:
1. Treat anxiety - Benzodiazapenes
2. Reduce pain - Opiod anaglesics such as morphine
3. Produce muscle paralysis -E.g. Tubocurare
4. Reduce secretions
Induction of anesthesia is often done via intravenous anesthetics, which are quick and easy to administer.
Maintenance of anesthesia involves inhalation agents.
Prototype Agents:
Volatile Anesthetics:
• Nitrous Oxide
• Ether
• Halothane
• Enflurane
• Isoflurane
Injectable Anesthetics:
• Thiopental
• Ketamine
• Etomidate
• Propofol
• Midazolam
Neuron Basic Structure (How brain cells communicate)
• Synapse:A junction between the terminal button of an axon and the membrane of another neuron
• Terminal button(orbouton):The bud at the end of a branch of an axon; forms synapses with another neuron; sends information to that neuron.
• Neurotransmitter:A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron.
Different types of Synapses
1-Axo-denrdritic
2-Axo-axonal
3-Axo-somatic
Chemical transmission in the CNS
The CNS controls the main functions of the body through the action endogenous chemical substances known as “neurotransmitters”.
These neurotransmitters are stored in and secreted by neurons to “transmit”information to the postsynaptic sites producing either excitatoryor inhibitory responses.
Most centrally acting drugs exert their actions at the synaptic junctions by either affecting neurotransmitter synthesis, release, uptake, or by exerting direct agonistor antagonistaction on postsynaptic sites.
Buspirone
1. Short half-life (2–4 hours).
2. Relieves anxiety.
3. Does not act as an anticonvulsant.
4. Is not a good muscle relaxant.
5. Minimum abuse potential.