NURS 3517 - Pharmacology - Test 2 (Drugs Affecting the CNS - Analgesic Drugs, General and Local Anaesthetic, Anti-inflammatory (Week 3) Drugs Affecting the CNS - CNS Depressants and Muscle Relaxants, Antiparkinsonian Drugs, Anti-Epileptic Drugs (Week 4) P

NURS 3517 - Pharmacology - Test 2 (Drugs Affecting the
CNS - Analgesic Drugs, General and Local Anaesthetic,
Anti-inflammatory (Week 3) Drugs Affecting the CNS - CNS
Depressants and Muscle Relaxants, Antiparkinsonian Drugs,
Anti-Epileptic Drugs (Week 4) Psychotherapeutics (Week 5)
Questions With Complete Solutions


Pain Tolerance
- The amount of pain a person can endure without it interfering
with normal function
- Varies from person to person
- Subjective response to pain, not a physiological function
- Varies by attitude, personality, environment, culture, ethnicity
Classification of Pain by Onset and Duration
Acute pain:
- Sudden onset
- Limited, has an end

Persistent pain (chronic pain):
- Persistent or recurring - Lasts 3 to 6 months
- More difficult to treat - Tolerance
Classification of Pain
- Referred
- Neuropathic
- Phantom
- Cancer

,- Central
- Vascular
Gate Theory of Pain Transmission
- Most common and well-described theory
- Uses the analogy of a gate to describe how impulses from
damaged tissues are sensed in the brain
- Many current pain management strategies are aimed at altering
this system.
Transduction
- Transformation of stimuli into electrochemical energy
- Release of pain-medicating chemicals
- Nociceptors
Pain Transduction
Tissue injury causes the release of the following:
- Bradykinin
- Histamine
- Potassium
- Prostaglandins
- Serotonin
- Substance P

- These substances stimulate nerve endings, starting the pain
process.
- The nerve impulses enter the"gate" dorsal horn of spinal cord
- This gate regulates the flow of sensory impulses to the brain
- Closing the gate stops the impulses

,- If no impulses are transmitted to higher centers in the brain,
there is no pain perception.
Pain Transmission
Two types of nociceptor pain fibres:
- Large-diameter, A-delta fibres, and small-diameter C fibres
- These pain fibers enter the dorsal horn and travel up to the
brain
Pain Perception
- Subjective phenomenon of pain
- Identical stimulus can evoke different pain from one individual
to another
- "How it is felt"
- Complex behavioral, psychological, and emotional factors
- The number of mu receptors in the dorsal horn appear to play a
crucial role in pain perception and emotional well-being
- The larger the number of mu receptors, the less pain is
perceived
Pain Modulation
- Neural activity that controls pain transmission to neurons
- Both peripheral and central nervous systems
- Descending pain system
- Enkephalins and endorphins
Treatment of Pain in Special Situations
- Patient-controlled analgesia (PCA)
- Patient comfort versus fear of drug addiction
- Opioid tolerance

, - Use of placebos
- Recognizing patients who are opioid tolerant
- Breakthrough pain
- Synergistic effects
Adjuvant Drugs
- Drugs from chemical categories other than opioids

Assist primary drugs in relieving pain:
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Antidepressants - Anticonvulsants - Corticosteroids

Example: adjuvant drugs for neuropathic pain - Amitriptyline
(antidepressant) - Gabapentin or pregabalin (anticonvulsants)
World Health OrganizationThree-Step Analgesic Ladder
Step 1: Nonopioids with or without adjuvant medications after
the pain has been identified and assessed. If pain persists or
increases, treatment moves to:

Step 2: Opioids with or without nonopioids and with or without
adjuvants. If pain persists or increases, management then rises
to:

Step 3: Opioids indicated for moderate to severe pain,
administered with or without nonopioids or adjuvant
medications
Opioid Drugs