Analgesia: Word Breakdown
Prefix “an-” means without
Suffix “-algesia” means pain, sensitivity
ANALGESIA: LACK OF SENSATIONS
A deadening or absence of the sense of pain
without the loss of consciousness.
An analgesic (also known as a painkiller) is
any member of the group of drugs used to
The main pharmacological action of
analgesics is on the cerebrum and medulla
of the central nervous system.
Classes of Analgesics
Paracetamol and NSAIDs
The exact mechanism of action of
paracetamol/acetaminophen is uncertain, but it appears
to be acting centrally (in the brain rather than in nerve
Aspirin and the other non-steroidal anti-inflammatory
drugs (NSAIDs) inhibit cyclooxygenases, leading to a
decrease in prostaglandin production.
This reduces pain and also inflammation (in contrast to
paracetamol and the opioids).
Classes of Analgesics (cont’d)
These drugs have been derived from NSAIDs.
Opiates and morphinomimetics
Morphine, the archetypal opioid, and various other
substances (e.g. codeine, oxycodone, hydrocodone,
dihydromorphine, pethidine) all exert a similar influence on
the cerebral opioid receptor system.
Flupirtine is a centrally acting K+ channel opener with weak
NMDA antagonist properties.
It is used in Europe for moderate to strong pain and migraine
and its muscle relaxant properties.
Found in paracetamol and codeine preparations found
in many non-prescription pain relievers.
Found in vasoconstrictor drugs such as
pseudoephedrine for sinus-related preparations, or with
antihistamine drugs for allergy sufferers.
Topical or Systemic
Topical analgesia is generally recommended to avoid
Painful joints, for example, may be treated with an
ibuprofen- or diclofenac-containing gel
Specific Forms (continued)
Tetrahydrocannabinol (THC) and some other
cannabinoids, either from the Cannabis sativa plant or
synthetic, have analgesic properties, although the use of
cannabis derivatives is currently illegal in many
A recent study finds that inhaled cannabis is effective in
alleviating neuropathy and pain resulting from e.g.
spinal injury and multiple sclerosis.
Specific Forms (continued)
Atypical and/or adjuvent analgestics
Orphenadrine, cyclobenzaprine, scopolamine, atropine,
gabapentin, first-generation antidepressants and other drugs
possessing anticholinergic and/or antispasmodic properties are
used in many cases along with analgesics to potentiate centrally
acting analgesics such as opioids when used against pain especially
of neuropathic origin and to modulate the effects of many other
types of analgesics by action in the parasympathetic nervous system
The use of adjuvant analgesics is an important and growing part of
the pain-control field and new discoveries are made practically
Many of these drugs combat the side effects of opioid analgesics.
Patient Controlled Analgesia (PCA)
Patient Controlled Analgesia (PCA) is a method of
pain control that gives the patient the power to control
Pain medication is administered through a
The pump contains a syringe of pain medication as
prescribed by a doctor that is connected directly to a
patient’s intravenous (IV) line.
The pump is set to deliver a small, constant flow of pain
Additional doses can be self-administered as needed by the
patient pressing a button.
Safety of PCA Pumps
PCA pumps have built in safety features.
The total amount of analgesic (pain reliever)
that a patient can self-administer is within a
Because of these features, there is no worry
Who uses PCA?
Patients recovering from surgery most
often are equipped with PCA pumps.
Patients coping with other kinds of
pain can also use the PCA pump.
Advantages of PCA
The physician determines the dosage based on the
patient’s weight to prevent overdose.
Narcotic addiction can be avoided because the drug is
taken on a short-term controlled basis.
Pain relief is available around the clock.
The PCA unit is programmed to control the dosage;
the unit “locks out” if the dosing frequency is
Most adults and children can use PCA
Disadvantages of PCA
The button on the PCA pump can be
accidentally pressed, delivering an
unneeded dose of medication.
If the PCA pump isn’t programmed properly,
results include an under-dose or overdose in
Prefix “an-” means without.
Suffix “-esthesia” means feeling, sensation.
Anesthesia means without feeling or
Local or general insensibility to pain with or
without the loss of consciousness, induced by an
anesthetic (drug that produces anesthesia).
Types of Anesthesia
There are four main types:
Local – numbs one small area of the body. You stay alert and
Conscious or IV sedation - uses a mild sedative to relax you
and pain medicine to relieve pain. You stay awake but may not
remember the procedure afterwards.
Regional anesthesia- blocks pain in an area of the body,
such an arm or leg. Epidural anesthesia, which is sometimes
used during childbirth, is a type of regional anesthesia.
General anesthesia- affects your whole body. You go to sleep
and feel nothing. You have no memory of the procedure
Features of Anesthesia
There are four features of anesthesia:
The lack of motor response to instructions
suppression of autonomic and skeletal responses to
intraoperative stimuli such as incisions
absence of retrospective awareness of pain
postoperative amnesia for surgical events such as
conversations among the medical team
How Does Anesthesia Work?
It is currently unknown how anesthesia works, but
there a number of plausible hypotheses.
The most common accepted theory is that that general
anesthetics operate directly on the central nervous
system to temporarily inhibit synaptic transmission (the
chemical means by which neural impulses are
transmitted between adjacent neurons).
This results in a general loss of consciousness that
affects sensory awareness in all modalities and at all
Major Differences Between
Analgesia and Anesthesia
Analgesia is lack of pain, anesthesia refers to lack of
Anesthesia is usually accompanied by analgesia
Patients are fully aware and awake while using
analgesia; with anesthesia, patient can be either
unconscious and asleep or awake and fully
Analgesia is patient controlled, anesthesia is
controlled by a person specializing in administration