Summer 2010 - The British Pain Society

to carry out any treatment that
a patient says he or she wants.
Doctors sometimes refuse to
prescribe antibiotics either because
the patient doesn't need them
or because over-prescription
could lead to antibiotic resistance
and put others at risk. Surgeons
sometimes have to refuse to
perform operations that patients
say they want but which are
considered futile or dangerous.
Similarly, patients cannot require
their doctors to kill them or to
help them kill themselves.
This bill has been designed around
the wishes of a small minority
of strong-minded and highlydetermined
people, but it would
put much larger numbers of less
resolute people at serious risk of
self-harm. It is not uncommon
for seriously ill people to think
in terms of 'ending it all' either
because of transient depression
or because they want to spare
their families a care burden - or,
in some cases, as a result of subtle
coercion by others. The law as it
stands protects them by putting
assisted suicide or euthanasia
safely out of reach. Responsible
law-making has to consider the
interests of the community as a
whole, and especially of its most
vulnerable members.
Laws can and do affect social
thinking. They provide a
benchmark of right and wrong,
indicating to many that 'if its
legal it must be ok'. This Bill runs
counter to suicide preventions
strategies. The Scottish Parliament
would be well advised to ignore
the spin and the soft euphemistic
wording and to read carefully what
Ms MacDonald's bill actually says
and to think about what it really
means.
PROFESSIONAL PERSPECTIVES
Diamorphine Necessary or Not?
The Home Offices recent Oxycodone consultation paper stated:
“The UK is a world leader in palliative care. It is one of the few countries in the world to use diamorphine, a
powerful opioid analgesic which has proved to have certain advantages over other painkillers. Diamorphine has a
more favourable side effect profile than morphine, in that it may cause less nausea and hypotension. Diamorphine
is also more soluble than morphine which means that effective doses can be administered in smaller volumes. This
is important in palliative care where patients may be emaciated.”
“It has a vital place in current clinical practice in the UK. The Government considers it essential that a suitable
supply of diamorphine is maintained.”
There has been an ongoing debate about the need to maintain diamorphine in the UK. This has been in part due
to the episodic shortages of the drug due to its reliance on one UK manufacturer. Here 2 BPS council members –
Dr Michael Platt and Professor Sam Ahmedazi put forward contrasting views on the evidence base for the need for
the continued supply of diamorphine in the UK.
Why diamorphine
should be retained
for pain management
Dr Michael Platt
Imperial College Healthcare NHS
Trust
Diamorphine was first synthesised
some 136 years ago in 1874
by Charles R. Alder-Wright at
St Mary’s Hospital Medical
School, following which it was
re-synthesised and manufactured
by Bayer, being released in the
same year as Aspirin some 23
years later 1 . Its brand name was
‘heroin’, meaning ‘strong’. It
has been used for the chronic
cough of tuberculosis, for pain
relief, breathlessness, cardiac
ischaemic pain and more recently,
intra-nasally for painful procedures
in Accident and Emergency 2 .
It is favoured by intravenous
drug mis-users because of its
potent and immediate ‘high’ or
‘rush’, producing a potent state
of euphoria. This phenomenon
highlights its main advantage over
morphine and other opioids, with
its greater lipid solubility, 200
times that of morphine 3 , due to
its two acetyl moieties, enabling
higher cell membrane transfer and
rapid tissue penetration.
It is used for pain management
either systemically, via
subcutaneous or intravenous
routes, or spinally, via the epidural
or intrathecal routes. In order to
reach the mu receptors, in the
dorsal horn of the spinal cord,
opioids have to penetrate the dura
and arachnoid layers and enter
the cerebrospinal fluid, before
penetrating the dorsal horn and
binding to mu receptors (with
lesser effects on delta and kappa
receptors), producing analgesia
via a G-protein coupling. When
administered intrathecally these
barriers are bypassed. Most
epidurally administered opioids
rapidly cross the dura, but the
rate of penetration across the
arachnoid mater is determined
by lipid solubility. Drugs with low
lipophilicity (e.g. morphine) cross
the arachnoid slowly and have
a slower onset of action; they
are cleared slowly, resulting in a
longer duration. Cephalad spread
of drugs with low lipophilicity
may result in delayed onset of
nausea and respiratory depression.
Drugs with higher lipid solubilities
(e.g. fentanyl) have a faster
onset, a shorter duration and are
associated with fewer late-onset
side-effects, but show more
localised segmental action at area
of spinal cord they are applied to,
with less spread and penetration
than diamorphine.
PAI N N E W S S U M M E R 2010 41