Bone Pain - Pharmacology and Prescribing Flashcards
What is an opiate?
Compounds that are found in te opium poppy e.g., morphine and codeine
What is an opiod?
Any substance, whether endogenous or synthetic, produces morphine - like effects that are blocked by anatagonists
Where does opium come from?
Extract from seed capsule of opium poppy (papaver somnifermu)
Describe products directly derived from opium
Opium poppy
- White milky latex containing alkaloids
- Varying proportion of morphine, codeine, thebaine
Purification
- Extraction focused on obtaining morphine
- Further processing to obtain morphine derivatives
Chemical modification
- Heroin (3,6-diacetylymorphine or diamorphine)
- Codeine (3-methylmorphien)
Other opiods can be synthesised. What are the two products thebaine is synthesised to?
- Oxycodone
- Hydrocodone
There are laboratory production of substances that act on similar receptors to natural opiods. List 3 examples of these substances
- Fentanyl
- Methadone
- Buprenorphine
Describe the chemical structure of opiods
Opioid activity comes from free hyrdoxyl on benzene ring, linked with carbon atoms to a nitrogen
There are three main types of receptors. Name the three receptors and describe their role
- Mu (for morphine) - analgesia, euphoria (but also constipations and respiratory depression)
- Kappa (for ketocyclazocine) - analgesic periphery (also dysphoria and hallucinations)
- Delta [for (vas) Deferencs in mice] - analgesics at spine
What type of receptors are the Mu-opiod peoptide receptors and describe their role
The Mu-opioid peptide receptors are G-protein coupled receptors. They open K+ channels and close Ca++ channels
List 6 of the most common opiods
- Morphine
- Codeine
- Diamorphine
- Methadone
- Oxycodone
- Fentanyl
What systems does morphine have an effect on?
- CNS
- GI
- Respiratory
List the pharmacological effects of morphine on the CNS
- Analgesia
- Euphoria (particularly with IV administration)
- Sedation
- Pupillary construction (stimulation of oculomotor nucleus brainstem)
List the pharmacological effects of morphine on the GI
- Nausea and vomiting - chemoreceptors trigger zone in
- Constipation - from reduced motility and muscle tightening
List the pharmacological effects of morphine on the respiratory
- Depression - inhibits respiratory centres in brainstem
- Suppress cough reflex
Describe some of the safety problems regarding morphine
- Acute - sedation, respiratory depression, vomiting
- Chronic - constipation
- Tolerance with recurrent use - causes desensitisation of mu receptors therefore increasing doses needed to achieve sufficience analgesisa
- Dependance causes problems with opioid withdrawal - Physical e.g., restlessness, aggression, runny nose, diarrhoea, shivering and also psychological eg., cravings may persist months and years