DRUG TRENDS
SA JOURNAL OF DIABETES & VASCULAR DISEASE
142
VOLUME 9 NUMBER 3 • SEPTEMBER 2012
Table 2.
Pathophysiological targets in pain management
1.
Peripheral activation
(
mainly prostaglandin mediated)
NSAIDS, COXibs
2.
Factors affecting transmission
e.g. increased sodium channels
Carbamazepine, lignocaine
3.
Conduction via afferent neurons to dorsal horn
(
alpha-2 delta subunit)
Pregabalin, gabapentin
4.
Dorsal horn receptors
(
NMDA receptors)
Ketamine (anaesthesia)
Gabapentinoids
5.
Spinal cord
(
COX-3 mediated and other mediators)
NSAIDS, paracetamol
6.
Brain
(
µ
,
κ
,
δ
receptors)
Opioids
7.
Modulation of the feedback mechanism (sero-
tonin and noradrenaline mediated)
Tramadol
SNRIs (selective noradrenaline reuptake inhibitors)
SSRIs (selective serotonin reuptake inhibitors)
New South African guidelines for the
management of neuropathic pain are
available on the
South African Medical
Journal
website:
php/smj/article/download/5472/4036.
Second-line therapy consists of a combi-
•
nation of these drugs.
Third-line therapy involves the use of
•
tramadol and the opioids (morphine,
oxycodone, fentanyl).
‘
Interestingly, our so-called proven use of
tricyclic antidepressants with their known
wide spectrum of side effects is based on a
very small study of 79 cases’, Dr Raff said.
‘
Gabapentin works, despite a host of side
effects including dizziness, somnolence and
peripheral oedema. Pregabalin is effective,
but it is essential to use a therapeutically
adequate twice-daily dose, between 75 and
150
mg bid’, Dr Raff noted.
Duloxetine at a dosage of 60 mg daily is the
recommendeddoseand there ismoreevidence
for its use in painful diabetic neuropathy (PDN)
than there is for venlafaxine use.
Oxycodone in controlled-release format is
nowavailable in South Africa. ‘It can however
take up to four weeks to provide pain relief
and patients must be prepared for this
treatment delay’, he noted. ‘Tramadol has
adequate but not large studies supporting
its third-line use.’
The therapeutic rationale for post-herpetic
neuralgia (PHN) is treatment with gabapentin,
pregabalin, TCAs, and strong opioids as they
have evidence of efficacy for PHN. The first-,
second- and third-line therapy is therefore
essentially the same for PNP and DPN.
Trigeminal neuralgia therapy options
are sparse with only carbamazepine and
oxcarbazepine achieving positive outcomes.
Therapy for central neuropathic pain
from spinal cord injuries and stroke is a
neglected field with few clinical trials. South
African guidelines suggest carbamazepine,
pregabalin or amitryptiline but note that
there is limited supporting evidence in this
category of patients.
‘
Non-pharmacological treatments, if they
work for the patient, should be positively
regarded by the attending physician’, Dr Raff
concluded.
J Aalbers
Dickenson AH,
1.
et al
.
Pharmacological treatment of
peripheral neuropathic pain conditions based on
shared commonalities despite multiple aetiologies.
Pain
2005;
113
(3): 251–254.
Ahal N,
2.
et al
.
EFNS guidelines on the pharmacological
treatment of neuropathic pain. 2010 revision.
Eur J
Neurol
2010;
17
: 1113-
e88.
Chetty S, Baalbergen E, Bhigjee AI, Kamerman
3.
P, Ouma J,
et al
.
Clinical practice guidelines from
management of neuropathic pain: expert panel
recommendations for South Africa.
S Afr Med J
2012;
102
(5): 312–325.
It's the
shell that
makes
safer.
Safety-Coated
R
81
mg
The ORIGINAL low dose aspirin
for optimum cardio-protection
Hp
Each tablet contains Aspirin 81mg. Reg.No.: 29/2.7/0767
Pharmafrica (Pty) Ltd, 33 Hulbert Road, New Centre, Johannesburg 2001
Under licence from Goldshield Pharmaceuticals Ltd. U.K.
Congratulations to Gerda van Rensburg on
winning the Ipad in our competition, which
was drawn at the CDE meeting recently.
