Pain control and controlled
drug prescribing
Gayle Munro
Specialist Pharmacist
22.03.10
Types of pain
Somatic
Activation of pain receptors in either
cutaneous or deep tissues (muscoloskeletal)
Cutaneous – sharp, burning, pricking
Deep – dull, aching (eg. bone mets)
Types of pain
Visceral
Internal areas of the body enclosed within
Cavity. Pain caused by infiltration,
compression, extension or stretching of the
thoracic, abdominal or pelvic viscera
eg. liver capsule pain.
Types of pain
Neuropathic
Damage to the nervous system:
Compression of nerves/spinal cord
Infiltration of nerves/spinal cord
Chemical damage – chemotherapy/XRT
Burning/tingling
Types of pain
All 3 types of pain can be acute or chronic
Acute: short-lived
Chronic: at least 3 month duration
Other factors affect the perception of pain:
Mood – depression, anxiety
Context – expectation, pain beliefs, placebo
Treatment
Pain can adversely affect a patient’s life in
many ways:
Personality
Quality of life
Ability to function
Good pain control is important
Assessment of pain
What the patient says it is!
Treatment
Assess cause of pain
Review current medication
Initiate treatment or
Step up the pain ladder or
Add adjuvant drug
WHO Pain Ladder
MILD: Paracetamol
MILD to MODERATE: Co-codamol 30/500, dihydrocodeine, tramadol
MODERATE to SEVERE: Morphine, diamorphine, oxycodone, hydromorphone,
Methadone
ADJUVANT: NSAID’s, TCA’s, anticonvulsants, corticosteroids, anxiolytics, muscle
relaxants, antimuscarinics
Controlled Drug Prescribing
• Patient’s name and address
• Name of drug and the FORM eg. tablet, patch
• Dose and frequency of administration
• Strength to be supplied
• Total quantity in words and figures
e.g. for MST 40mg bd 7 day supply
14 (fourteen) 10mg tablets and
14 (fourteen) 30mg tablets
Opioids
Act on opiod receptors: Mu, kappa
Initial side-effects
N&V, drowsiness, unsteadiness, confusion
On-going side-effects
Constipation
Occasional side-effects
Dry mouth, sweating, pruritus, hallucinations, myoclonus
Rare
Respiratory depression, psychological dependence
Opioids
Conversion from Morphine
Drug
Potency
Codeine
1/10th
Tramadol
1/10th - 1/5th
Oxycodone
2
Hydromorphone
7.5
Methadone
10
Fentanyl patch 25mcg/hr = 90mg/24h
Opioids
Convert co-codamol 30/500, 2 tabs qds
to MST in a patient who has used 4
breakthrough doses of oramorph 10mg in 24
hours.
Opioids
Convert 60mg bd of MST to
Oxycodone
Hydromorphone
What would the breakthrough dose be?
What other regular medication should be
prescribed?
Opioids
Oral to subcutaneous route
Oral
Morphine
Morphine
Oxycodone
Hydromorphone
Morphine
Morphine
Subcutaneous
Morphine ÷ 2
Diamorphine ÷ 3
Oxycodone ÷ 2
Hydromorphone ÷ 2*
Fentanyl ÷ 200**
Alfentanil ÷ 30**
*Different ranges quoted in the literature
**Seek advice from HPCT
Opioids
Convert a fentanyl 50mcg/hr patch to a
diamorphine syringe driver.
The patient is stabilised on diamorphine
90mg/24hrs after titration of the dose. Convert
back to a fentanyl patch.
What issues do you need to consider?
Opioid Choice
Morphine most commonly used
Oxycodone/Hydromorphone – less CNS
side-effects
Fentanyl – less constipation
Fentanyl/Alfentanil – good in renal
Impairment (shorter half-life)
Opioids
Management of side-effects
Initiation of opioid – antiemetic for first few days
Regular laxative
Hallucinations – haloperidol (nausea) or switch
Myoclonus – reduce dose, switch or benzodiazepine
Drowsiness – reduce dose or switch
Pruritus – antihistamine or switch if does not settle
Respiratory depression - naloxone
Adjuvant Drugs
Can be used at any point in the pain ladder
NSAID’s
bone pain (watch renal function, other medicines,
platelet count)
Diclofenac 50mg tds (rectal route available)
Corticosteroids
Reduce inflammation (cerebral mets, spinal cord
compression, liver capsule pain),
stimulate appetite, antitumour effect (lymphoma etc)
Adjuvant Drugs
Neuropathic pain
TCA’s
amitriptyline (small doses may suffice)
Anti-convulsants
Carbamazepine 100-200mg tds
Na Valproate 200mg tds
Gabapentin titrate dose gradually
300mg nocte day 1,
300mg bd day 2,
300mg tds day 3 then
increase up to 900mg tds. Elderly patients, start with a 100mg dose
and titrate. Watch renal function.
Adjuvant Drugs
Anxiolytics (agitation, dyspnoea)
Agitation, dyspnoea
Diazepam 2mg tds
Lorazepam 0.5-1mg Sub-lingual 8-12hrly
Midazolam 2.5mg s/c or 10-30mg via
syringe driver
Muscle Relaxants (muscle spasm pain)
Diazepam 2mg tds prn
Baclofen 5mg tds increased every 3 days to 20mg tds
Antimuscarinics (colic)
Hyoscine Butylbromide 20mg qds
Adjuvant Drugs
Ketamine
Reduces opioid requirement
Neuropathic pain – HPCT advice
Oral 50mg in 5ml – titrate dose usually start
10mg (1ml) qds
Subcut – usually start 50mg/24hrs and
titrate
Side-effects - hallucinations
Adjuvant Treatment
• A single fraction of radiotherapy can be
used for pain control
Answers
Co-codamol 30/500
2 tabs qds = 240mg codeine ÷ 10
= 24mg morphine + 40mg from breakthrough
= 64mg morphine
Give MST 30mg bd + 10mg oramorph hourly as required
for breakthrough pain (1/6th total daily dose)
Answers
Oxycodone is twice as potent as morphine therefore divide
morphine dose by 2
Give oxycodone sustained release tablets (oxycontin)
30mg bd with oxycodone normal release (oxynorm) 10mg
hourly as required for breakthrough pain
Hydromorphone is 7.5 times more potent therefore divide
morphine dose by 7.5
Give hydromorphone sustained release capsules 8mg bd
with hydromorphone normal release capsules 2.6mg hourly
as required for breakthrough pain
Always prescribe a laxative
Answers
Fentanyl 50mc/hr patch is equivalent to oral morphine
180mg in 24 hours. Divide oral morphine dose by 3 to get
diamorphine dose. Give 60mg diamorphine subcutaneously
via syringe driver over 24 hours
To convert subcutaneous diamorphine back to oral morphine
multiply by 3 = 270mg morphine which is equivalent to a
75mcg/hr fentanyl patch.
It takes 12-24 hours after a fentanyl patch is started to reach steady state
and 12-24 hours after a patch is removed for the reservoir of drug in the
skin to be depleted. When changing from a syringe driver to a patch,
keep the driver going for approx 12 hours after the patch has been
applied.
Questions
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