Non-opioid analgesics and compound analgesic
preparations
Paracetamol has analgesic and antipyretic properties but no
demonstrable anti-inflammatory activity; unlike opioid
analgesics, it does not cause respiratory depression and is
less irritant to the stomach than the NSAIDs.Overdosage
with paracetamol is particularly dangerous as it may cause
hepatic damage which is sometimes not apparent for 4 to
6 days.
Non-steroidal anti-inflammatory analgesics(NSAIDs)
are particularly useful for the treatment of children with
chronic disease accompanied by pain and inflammation.
Some of them are also used in the short-term treatment of
mild to moderate pain including transient musculoskeletal
pain but paracetamol is now often preferred. They are also
suitable for the relief of pain indysmenorrhoeaand to treat
pain caused bysecondary bone tumours, many of which
produce lysis of bone and release prostaglandins. Due to an
association with Reye’s syndrome, aspirin p. 91 should be
avoided in children under 16 years except in Kawasaki
disease or for its antiplatelet action. Several NSAIDs are also
used for postoperative analgesia.
Compound analgesic preparations
Compound analgesic preparations that contain a simple
analgesic (such as paracetamol) with an opioid component
reduce the scope for effective titration of the individual
components in the management of pain of varying intensity.
Compound analgesic preparations containing paracetamol
with alow doseof an opioid analgesic (e.g. 8 mg of codeine
phosphate per compound tablet) may be used in older
children but the advantages have not been substantiated.
The low dose of the opioid may be enough to cause opioid
side-effects (in particular, constipation) and can complicate
the treatment ofoverdosageyet may not provide significant
additional relief of pain.
Afull doseof the opioid component (e.g. 60 mg codeine
phosphate) in compound analgesic preparations effectively
augments the analgesic activity but is associated with the
full range of opioid side-effects (including nausea, vomiting,
severe constipation, drowsiness, respiratory depression, and
risk of dependence on long-term administration).
In general, when assessing pain, it is necessary to weigh up
carefully whether there is a need for a non-opioid and an
opioid analgesic to be taken simultaneously.Opioid analgesics and dependence
Opioid analgesics are usually used to relieve moderate to
severe pain particularly of visceral origin. Repeated
administration may cause tolerance, but this is no deterrent
in the control of pain in terminal illness. Regular use of a
potent opioid may be appropriate for certain cases of chronic
non-malignant pain; treatment should be supervised by a
specialist and the child should be assessed at regular
intervals.Strong opioids
Morphine remains the most valuable opioid analgesic for
severe pain although it frequently causes nausea and
vomiting. It is the standard against which other opioid
analgesics are compared. In addition to relief of pain,
morphine also confers a state of euphoria and mental
detachment.
Morphine is the opioid of choice for the oral treatment of
severe pain in palliative care. It is given regularly every
4 hours (or every 12 or 24 hours as modified-release
preparations).
Buprenorphine p. 274 has both opioid agonist and
antagonist properties and may precipitate withdrawal
symptoms, including pain, in children dependent on other
opioids. It has abuse potential and may itself cause
dependence. It has a much longer duration of action than
morphine and sublingually is an effective analgesic for 6 to8 hours. Unlike most opioid analgesics, the effects of
buprenorphine are only partially reversed by naloxone
hydrochloride p. 842. It is rarely used in children.
Diamorphine hydrochloride p.^277 (heroin) is a powerful
opioid analgesic. It may cause less nausea and hypotension
than morphine p. 282 .Inpalliative carethe greater solubility
of diamorphine hydrochloride allows effective doses to be
injected in smaller volumes and this is important in the
emaciated child. Diamorphine hydrochloride is sometimes
given by the intranasal route to treat acute pain in children
and is available as a nasal spray; intranasal administration of
diamorphine injection has been used [unlicensed].
Alfentanil p. 818 , fentanyl p. 279 and remifentanil p. 819
are used by injection for intra-operative analgesia. Fentanyl
is available in a transdermal drug delivery system as a self-
adhesive patch which is changed every 72 hours.
Methadone hydrochloride p. 299 is less sedating than
morphine and acts for longer periods. In prolonged use,
methadone hydrochloride should not be administered more
often than twice daily to avoid the risk of accumulation and
opioid overdosage. Methadone hydrochloride may be used
instead of morphine when excitation (or exacerbation of
pain) occurs with morphine. Methadone hydrochloride may
also be used to treat children with neonatal abstinence
syndrome.
Papaveretum p. 287 should not be used in children;
morphine is easier to prescribe and less prone to error with
regard to the strength and dose.
Pethidine hydrochloride p. 287 produces prompt but
short-lasting analgesia; it is less constipating than
morphine, but even in high doses is a less potent analgesic.
Its use in children is not recommended. Pethidine
hydrochloride is used for analgesia in labour; however, other
opioids, such as morphine or diamorphine hydrochloride, are
often preferred for obstetric pain.
Tramadol hydrochloride p. 287 is used in older children
and produces analgesia by two mechanisms: an opioid effect
and an enhancement of serotonergic and adrenergic
pathways. It has fewer of the typical opioid side-effects
(notably, less respiratory depression, less constipation and
less addiction potential); psychiatric reactions have been
reported.Weak opioids
Codeine phosphate p. 276 can be used for the relief of short-
term acute moderate pain in children older than 12 years
where other painkillers such as paracetamol p. 271 or
ibuprofen p. 655 have proved ineffective.
Dihydrocodeine tartrate p. 278 has an analgesic efficacy
similar to that of codeine phosphate.
Postoperative analgesia
A combination of opioid and non-opioid analgesics is used to
treat postoperative pain. The use of intra-operative opioids
affects the prescribing of postoperative analgesics. A
postoperative opioid analgesic should be given with care
since it may potentiate any residual respiratory depression.
Morphine is used most widely. Tramadol hydrochloride is
not as effective in severe pain as other opioid analgesics.
Buprenorphine p. 274 may antagonise the analgesic effect of
previously administered opioids and is generally not
recommended. Pethidine hydrochloride is generally not
recommended for postoperative pain because it is
metabolised to norpethidine which may accumulate,
particularly in neonates and in renal impairment;
norpethidine stimulates the central nervous system and may
cause convulsions.
Opioids are also given epidurally [unlicensed route] in the
postoperative period but are associated with side- effects
such as pruritus, urinary retention, nausea and vomiting;
respiratory depression can be delayed, particularly with
morphine.270 Pain BNFC 2018 – 2019
Nervous system4