What are the pharmacological actions of Non-steroidal anti-inflammatory drugs?
Antipyretic - reduce body temperate during fever
Analgesic - relief of pain associated with increased production of PGs eg. arthritic, muscular, dental pain, post-partum, bone cancer pain
Anti-inflammatory - reduce oedema, sensitisation of nociceptors
Side effects of NSAIDS and how to reduce
Indigestion, diarrhoea, nausea, vomiting, gastric bleeding, ulceration
Reduce side effects by developing drugs that only inhibit cox2 enzyme, have enteric coating of tablets, administer pro-drugs eg. sulindac
Aspirin
NSAID
Effective against mild pain and fever Non-selective cox inhibitor Should not be given to: - children under 16 - history of peptic ulcers - haemophilia/ other bleeding disorders - patients taking anti-coagulant drugs - liver disease
Ibuprofen
NSAID
Non-selective cox inhibitor
1st choice drug as has less risk of side effects compared to aspirin however can cause indigestion/peptic ulcers
eg. Naproxen - more potent, longer lasting so fewer doses
eg. Dexibuprofen, Fenbufen, Ketoprofen
Paracetomol
NSAID
Antipyretic Analgesic Limited anti-inflammatory action Used to treat children Toxic to the liver 2/3 times the normal therapeutic dose
NSAIDs and opioid analgesics
Eg. Co-codamol (aspirin and codeine phosphate)
Eg. Co-codaprin (Paracetomol and codeine phosphate)
Increased number of side effects
Opioid analgesics
Enkephalins, endorphins and dynorphins
Bind to opioid receptors
Used for pain of visceral origins eg. surgery, terminal illness
Action:
- encephalin released
- binds to opioid receptors on AO/C fibres
- substance P release inhibited (inhibits Ca+ influx)
- signal not transmitted to thalamus
Examples:
- Mild/moderate pain = codeine, dihydrocodeine, meptazinol
- Moderate/severe pain = MORPHINE, diamorphine (heroin), tramadol
- Intraoperative analgesia = fentanyl, alfentanil
- Postoperative analgesia = morphine
-Overdose = naloxone
Morphine
Acute/chronic pain (palliative care)
State of euphoria/mental detachment
Slowly absorbed by the mouth to give a sustained release
IV/IM/subcutaneous/rectal administration also
Side effects: constipation, nausea/vomiting, sedation, confusion, hallucinations, dependency, respiratory depression
Local anaesthetics
Can be applied topically to skin or mucosal surfaces or by subcutaneous injection to act on nerve endings
Nerve block: anaesthetic infiltrated around a nerve
Intravenous regional anaesthesia
Examples: lidocaine, bupivicaine, prilocaine, tetracaine