COMPLEMENTARY THERAPY: Herbal Medicines Cannabis and other herbal medicines Flashcards
what are the three types of cannabinoids?
– Endocannabinoids • Anandamide (AEA) • 2-arachidonoylglyerol (2-AG) – Phytocannabinoids • From plants – Synthetic cannabinoids • E.g. spice, nabilone, K2, dronabinol
what does endocannabinoid system regulate?
– sleep – mood – appetite – memory – reproduction and fertility
what are the two neurotransmittera?
• 2-arachidonoylglyerol (2-AG)
– Present at relatively high levels within the central nervous system
– Responsible for basal endocannabinoid signalling
– Is a much more potent agonist (activator) of CB1 receptors
• Anandamide (AEA)
– Present at very low levels and has a very short half-life
– Formation is induced by stress
– Is much less effective at activating CB1 receptors and can sometimes anatgonise (block) the effects of 2-AG
what are the main ingredients in phytocannabinoids?
tetrahydrocannabindol (THC) and Cannabidiol (CBD)
what is THC?
• Tetrahydrocannabinol – Lipid soluble • Mechanism of action – Partial agonist at cannabinoid receptors • CB1 – CNS CB2 – Immune system • Leads to decreased levels of cAMP – Mild antioxidant
what are the uses of THC/
– Licensed in US weight loss in patients with AIDS
– nausea and vomiting in people receiving chemotherapy
what is CBD?
• Cannabidiol (CBD) – Lipid soluble • Mechanism of action: – alters the shape of CB1 recepto which prevents activation by endocannabinoids. – It does not have any psychoactive effects • Availability – Health food shops • not regulated as a medicine
what are the uses of cbd?
– licensed in US for two rare and severe forms of childhood epilepsy
what are the pharmacokinetics of cannaniboids?
Absorption – Inhalation • Rapid onset and good bioavailability – Oral • Slow onset and poor bioavailability Distribution – Lipid soluble • Rapid accumulation in fatty tissues Metabolism – THC metabolites are active
what are the prescribing laws for cannabis in the UK?
• Prescribing is restricted to those on the GMC specialist register and within their speciality.
– Must have clear published evidence or UK guidelines to support treatment
– Only when clinical need cannot be met by a licensed medicine; and when established treatment options have been exhausted.
– Also need
• authorisation from the medical director
• agreement from the multidisciplinary team, using existing protocols on controlled drugs.
who is authorised to procure unlicensed CBPMs in the UK?
• a) Doctor on the GMC Specialist Register
• b) Specialist Importer with a Home Office import and Domestic licence and MHRA licence
• c) Registered pharmacies or retail pharmacy businesses (with Home Office Domestic licences, where appropriate)
– Some pharmacies will NOT need a domestic licence – as pharmacies and retail pharmacy business are able to produce / supply in accordance with their practice. However, if they are wholesale dealing the policy is that they do need a licence.
• d) Licensed wholesale dealers for supply
what is sativex?
- Patented by GW pharmaceuticals
- Licensed in the UK for moderate to severe spasticity in adult patients with MS
- A natural cannabis product which contains a 1:1 ratio of THC and CBD, and many other cannibinoids
- NICE does not recommend that patients are prescribed Sativex
- The only natural cannabis product licensed for use in the UK
how much does a vial of sativex cost the NHS?
£120 per 10 mL vial
what is dronabinol?
- Synthetic product which is identical to THC
- Produced in UK
- Unlicensed in the UK
- Assigned to schedule 2, prescribed on a named patient basis
- Can be prescribed for nausea and vomiting due to chemotherapy which is unresponsive to conventional antiemetics
what is nabilone?
- Synthetic product structurally similar to THC
- Produced in UK Licensed in the UK
- Assigned to schedule 2,no restrictions on prescribing, GPs can continue prescriptions
- Can be prescribed for nausea and vomiting due to chemotherapy which is unresponsive to conventional antiemetics
what are the adverse effects of cannabinoids?
Schizophrenia
• THC heavy cannabis such as skunk likely increases the risk of developing psychosis and causes an earlier emergence of symptoms. Cannabis alone is unlikely to be the sole cause.
• CBD heavy cannabis such as hash, may in fact be helpful in treating neuropsychiatric diseases
Memory loss
• Complex and multifactorial issue, but smoking regularly before the brain finishes developing (early twenties) may lead to poorer academic performance
Dependence
• Cannabis is thought to be addictive in about 9% of cases of heavy use
• Withdrawal symptoms, such as irritability, typically resolve within three days of cessation of use
what is echinacea?
• It is claimed that this herbal remedy
– Improves natural immunity
– prevent colds
– shorten duration of colds
• Evidence for benefit - Cochrane
– 24 double-blind trials (n=4631)
– None of the 12 prevention studies reported a statistically significant difference between Echinacea and placebo. However a post hoc pooling of their results, suggests a relative risk reduction of 10% to 20%.
– Two of the six treatment trials reported a significant effect of Echinacea over placebo.
– The number of patients dropping out or reporting adverse effects did not differ significantly between treatment and control groups in prevention and treatment trials.
– Conclusion - have not shown benefit for treating colds, it is possible there is a weak benefit in prophylaxis
what is the safety aspects of echinacea/
• Do not use if – pregnant – under 12 years of age – suffer from: • frequent allergic reactions • tuberculosis, multiple sclerosis, • connective tissue disease • auto immune disease, HIV or AIDS, low white cell count, • bone marrow disorders or blood cell cancer • Receiving immunosupression
what is valerian?
• It is claimed that this herbal remedy
– Aids sleep
– Stress relief
• Evidence for benefit
– RCT (n= 36) generalised anxiety disorder
– 4 week study of valerian, diazepam and placebo.
– no significant differences between the valerian and placebo groups and between the valerian and diazepam groups.
– no significant differences between the three groups in reporting side effects
– Authors - insufficient evidence to draw any conclusions about the efficacy or safety of valerian compared with placebo or diazepam for anxiety disorder
what are the safety precautions behind valerian?
– Safety not established in • Patients under 18 years • Pregnant or breastfeeding – Don’t take with • Other sleep or anxiety medication • Other medicines affected by alcohol
