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Flashcards in Pain E-book Deck (35)
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Adjuvant analgesics

- Adjuvant analgesics (also known as co-analgesics) are drugs with a primary
indication other than pain which are used for analgesia.
- Adjuvants may be used in both acute and chronic pain and are recommended by
WHO at all stages of the pain ladder (see stage 3 pain module and section 4 of this
eBook). They are of particular value in neuropathic, post-operative and cancer pain.


Types of adjuvant
analgesics & examples

-Alpha-2 agonists Clonidine

-Antidepressants Amitriptyline

-Anticonvulsants Gabapentin

-Bisphosphonates Pamidronate
Zoledronic acid

-Corticosteroids Dexamethasone

-NMDA receptor

-Topical agents Capsaicin


Neuropathic pain

Neuropathic pain occurs when there is damage to, or a change within, the central or
peripheral nervous systems. This may occur with Herpes zoster infections (the pain
of shingles), direct damage to, or compression of, a nerve (e.g. sciatica), tumour
infiltration of a nerve or as the result of chemotherapy for cancer. The pain may be
continuous or consist of unpredictable episodes, the latter often being likened to
having an electric shock.


Neuropathic pain is often described as:

• Tingling
• Burning
• Electrical
• Stabbing
• Pins & needles
• Itching


Tactile allodynia

This is when even a very light touch on the skin of the patient will result in the sensation of severe pain in the area and the patient may find the touch of clothing or bedclothes intolerable.


Neuropathic pain often responds very poorly to

conventional analgesia and drugs
which work centrally may be more effective. These include (not an exhaustive list):
amitriptyline, carbamazepine, duloxetine gabapentin, pregabalin, tramadol.


Phantom Limb Pain

Phantom Limb Pain (PLP) affects 50-80% of amputees. It is often confused with
residual-limb or stump pain or amputation pain. These are nociceptive types of pain,
whereas PLP is a neuropathic pain. Pressure on the residual limb, certain times of
the day and the weather can make the pain worse, as can emotional stress. The
pain is often described as sharp, cramping, burning, electric, jumping, crushing and
cramping. Often the pain is associated with particular movements or positions of the
phantom limb. It differs from phantom limb sensation, which is a normal
phenomenon for almost all amputees, but unlike PLP, is not distressing. Phantom sensation has been described as itchiness, tingling or pins and needles, squeezing
and toe crossing.


Post-operative Pain operative P

Post-operative pain is usually acute and usually decreases in the days following
surgery. Inadequate control of pain within the post-operative period can lead to the
pain becoming chronic

The WHO pain ladder (refer back to your stage 3 pain module) is used to treat acute
pain such as post-operative pain


WHOs pain relief ladder

1 (mild pain) Paracetamol and NSAIDs

2 (mild – moderate pain) Paracetamol and NSAIDs plus weak opioid
e.g. codeine or dihydrocodeine

3 (severe pain) paracetamol and NSAIDs plus strong opioids
(eg morphine, alfentanil, diamorphine,
fentanyl, or oxycodone)


Non-opioids used may include

paracetamol or NSAIDs e.g. ibuprofen. Non-opioids
are administered orally or rectally (although rectal adsorption of paracetamol can
often lead to sub-therapeutic levels).


Opioids used may include (amongst others):

• Codeine (weak opioid)
• Dihydrocodeine (weak opioid)
• Tramadol (moderate opioid)
• Morphine (strong opioid)
• Diamorphine (strong opioid)
• Oxycodone (strong opioid)
• Fentanyl (strong opioid)
• Buprenorphine (strong opioid)
• Pentazocine (strong opioid)
• Tapentadol (strong opioid)


Patient controlled analgesia (PCA)

PCA allows a patient to administer their own pain relief; a syringe containing the
chosen drug is inserted into the computerised pump. The pump can be set to
administer prescribed doses of the drug when the patient presses the button on the
pump, there will be a ‘lock-out’ period whereby if the patient presses the button they
will not receive any further doses thus minimising the risk of overdose. Alternatively
the pump can be set to administer a small constant flow of analgesia; additional
doses can also be administered by the patient pressing the button. The usual route
for PCA is IV. The video in the recommended reading shows a PCA being used in
adolescent patients.


Adjuvant therapies that might be used may include (amongst others):

• Entonox (50% nitrous oxide 50% oxygen)
• Antidepressants e.g. amitriptyline
• Anticonvulsants e.g. gabapentin, pregabalin
• NMDA-receptor antagonists e.g. ketamine


more likely to be used in the immediate
post-operative period

Entonox and ketamine


antidepressants and anticonvulsants are more likely to be

if other first line options are not adequately controlling a patients’ pain.


Pain associated with burns can originate in many different ways. For example:

• Pain associated with the burn itself
• Dressing changes
• Donor graft sites
• Nerve regrowth


useful for dressing changes.

Remifentanil, is a very short acting opioid, which is useful for dressing changes


used for procedural pain

Ketamine or inhaled nitrous oxide


The pain from fractures may be described as a deep, intense ache. Some people
also experience sharp pain with broken bones. Patients may also feel:

• Bruising
• Stiffness
• Swelling
• Warmth
• Weakness.


The pain
associated with non-complex fractures of the arm or leg bones in adults is managed

• oral paracetamol for mild pain
• oral paracetamol and codeine for moderate pain
• intravenous paracetamol supplemented with intravenous morphine titrated to
effect for severe pain.


NSAIDs should not be considered in

frail or older adults due to
the risk of NSAIDs impeding the bone healing process


The pain associated with non-complex fractures of the arm or leg bones in children
under 16 is managed with:

• oral ibuprofen, or oral paracetamol, or both for mild to moderate pain
• intranasal or intravenous opioids for moderate to severe pain (use intravenous
opioids if intravenous access has been established).


suspected displaced femoral fractures

A femoral nerve block or fascia iliaca block may be used in the emergency
department for children (under 16s) with suspected displaced femoral fractures.


Complex fractures

IV Morphine should be used as first line
with ketamine as second line.


ACS includes:

• Unstable angina
• Non-ST elevation myocardial infarction (NSTEMI)
• ST elevation myocardial infarction (STEMI).


ACS pain relief

Pain relief should be provided as soon as possible. Buccal or sublingual GTN may
provide this relief however IV opioids e.g. morphine or diamorphine should be
offered, particularly in STEMI or NSTEMI


Treatment for
All neuropathic pain (except trigeminal neuralgia)

Offer a choice of amitriptyline, duloxetine, gabapentin or pregabalin as initial treatment for neuropathic pain (except trigeminal neuralgia.

If the initial treatment is not effective or is not tolerated, offer one of the remaining 3 drugs, and consider switching again if the second and third drugs tried are also not effective or not tolerated.

Consider tramadol only if acute rescue therapy is needed.

Consider capsaicin cream for people with localised neuropathic pain who wish to avoid, or who cannot tolerate, oral treatments.


Do not start the following to treat neuropathic pain in non-specialist settings, unless advised by a specialist to do so:

cannabis sativa extract

capsaicin patch







tramadol (long-term use)


sodium valproate


Trigeminal neuralgia treatment

Offer carbamazepine as initial treatment for trigeminal neuralgia.

If initial treatment with carbamazepine is not effective, is not tolerated or is contraindicated, consider seeking expert advice from a specialist and consider early referral to a specialist pain service or a condition-specific service.


For patients with major trauma, use

intravenous morphine as the first‑line analgesic and adjust the dose as needed to achieve adequate pain relief.

If intravenous access has not been established, consider the intranasal route for atomised delivery of diamorphine or ketamine.

Consider ketamine in analgesic doses as a second‑line agent.