NURS 2550H Chapter 5: Week 5 readings
26 Jun 2018
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NURS 2550
CH 20- Intro to CNS pharmacology
- CNS drugs are agents that act on the brain and spinal cord
- They relieve pain, suppress seizures, produce anesthesia, and treat psychiatric disorders
- We are a long way from fully understanding the CNS and the drugs used to affect it
Transmitters of the CNS
- The PNS only has 3 compounds (acetylcholine, norepinephrine and epinephrine) that
serve as neurotransmitters
- The CNS contains at least 21 compounds that serve as neurotransmitters
- There are numerous sites within the CNS for which no transmitter has been identified
The Blood Brain Barrier
- Passage across the barrier is limited to lipid-soluble agents and to drugs that cross by
way of specific transport systems
- The barrier protects the brain from injury by potentially toxic substances, but it can also
be a significant obstacle to entry of therapeutic agents
- Blood-brain barrier is not fully developed as an infant
How do CNS drugs produce a therapeutic effect?
- In the case of most CNS disorders, our knowledge is limited
- Must exercise caution when attempting to assign a precise mechanism for a drug’s
therapeutic effects
- Although we can’t state with certainty how CNS drugs act, there are plausible
hypotheses
Adaptation of the CNS to Prolonged drug exposure
- Increased therapeutic effect: taken for several weeks before full therapeutic effects
develop
- Decreased side effects: the intensity of side effects decreases (while therapeutic effects
remain undiminished)
- Tolerance and physical dependence: special manifestations of CNS adaptation
oTolerance- a decreased response occurring during prolonged drug use
oPhysical dependence- abrupt discontinuation of drug use will precipitate a
withdrawal syndrome
Development of new psychotherapeutic drugs
- We lack adequate animal models of mental illness
- Mentally healthy individuals cannot be used as subjects to assess potential
psychotherapeutic agents, because most psychotherapeutic drugs either have no effect
on a healthy person or paradoxical effects
Approaching the study of CNS drugs
- All we need to know about CNS transmitters (unlike PNS transmitters) is:
1
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Document Summary
Cns drugs are agents that act on the brain and spinal cord. They relieve pain, suppress seizures, produce anesthesia, and treat psychiatric disorders. We are a long way from fully understanding the cns and the drugs used to affect it. The pns only has 3 compounds (acetylcholine, norepinephrine and epinephrine) that serve as neurotransmitters. The cns contains at least 21 compounds that serve as neurotransmitters. There are numerous sites within the cns for which no transmitter has been identified. Passage across the barrier is limited to lipid-soluble agents and to drugs that cross by way of specific transport systems. The barrier protects the brain from injury by potentially toxic substances, but it can also be a significant obstacle to entry of therapeutic agents. Blood-brain barrier is not fully developed as an infant. In the case of most cns disorders, our knowledge is limited. Must exercise caution when attempting to assign a precise mechanism for a drug"s therapeutic effects.
