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

Codeine Tramadol Oxycodone

Potency

1/10 th 1/10 th - 1/5 th 2 Hydromorphone Methadone 7.5

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 (1/6 th 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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