Pharmacology Flashcards
Classes of psychotropic medications
Anxiolytics
Anti-depressants
Antipsychotics
Mood Stabilizers
Stimulants
Anxiolytics
Anti-anxiety agents: Benzodiazepines
Diazepam
Clonazepan
Lorazepam
Nitrazepam
Benzos all have a different “half-life” influencing the speed, period and intensity of action required
Benzodiazepines: Mechanism of action and indications
Enhance the effects of gamma-aminobutyric (GABA) on the receptor sites
Used in all major anxiety conditions
Sedation in cases of agitation (often PRN)
Alcohol withdrawal syndrome
Sleep disturbance
Anti convulsant
Muscle relaxant
Benzodiazepines: Major Side Effects
Drowsiness, light-headedness and confusion
Unsteadiness (especially in older people, who may have falls and injure themselves as a result)
Dizziness and blurred vision.
Slurred speech
Muscle weakness
Memory problems
Constipation
Nausea and dry mouth
Benzodiazepines: Other issues.
Prescribing is restricted in many countries because of potential for tolerance, addiction.
For this reason Benzos are rarely prescribed long term, however their short term use in acute psychiatry is common.
Severe physical withdrawal syndrome.
Anti-depressants
Anti-depressants are the most commonly prescribed psychotropic medication
Commonly prescribed by GP’s in primary care
Recommended for mild-moderate depression in conjunction with evidence based psychological therapies
Anti-Depressants: Selective Serotonin Re-uptake Inhibitors
SSRI’s
Work very specifically to prevent the re-uptake of serotonin to maximize it’s potential in the synapse
SSRI’s are very specific, there are few side effects, much less associated with addiction and tolerance than first generation anti-depressants
Used to treat all forms of depression
Some are licensed for use in certain anxiety disorders.
Other Anti-depressants
Selective Noradrenaline Re-uptake Inhibitors
- Work very similarly to SSRI’s but targeting the re-uptake of noradrenaline
- This has been found to be particularly useful in depression complicated by anxiety conditions.
Monoamine Oxidase Inhibitors (Monoamine MAOIs).
- Withdrawn in many countries because of dietary contra-indications and side effects with tyramine.
Tricyclics: First generation anti-depressants.
- Less specific in action and often sedating. Generally a wider side-effect spectrum and association with addiction and tolerance.
Anti-depressants: Common side effects
Agitation and anxiety
Nausea
Indigestion, diarrhoea or constipation
Loss of appetite, weight loss/gain
Dizziness & blurred vision
Dry mouth
Excessive sweating
Issues with libido
Anti-psychotics
There are two types of anti-psychotics that you will come across working in acute mental health environments.
“Typical” antipsychotics: First generation
“A-typical” antipsychotics: Second generation
Typical anti-psychotics
Originally used as antihistamines, anti-psychotic properties when given in high doses discovered in the 1950’s.
Developed and used for their anti-psychotic and tranquillizing properties, and continue to be used extensively.
Often referred to as “major tranquilizers” or neuroleptics.
Associated with severe Extra-pyramidal Side Effects (EPSE)
Typical Anti-psychotics:
Mechanism of action and indications.
Their primary action is the blocking of dopamine receptors in the brain as per the “dopamine hypothesis”. Very simply, if dopamine receptors are blocked, dopamine can’t sit on and stimulate the receptor sites.
However they’re very unspecific in their selection, blocking lots of other receptors and causing severe side effects.
Used for:
- Acute psychotic episodes (all types)
- Schizophrenia
- Acute agitation and arousal
Side Effects of typical anti-psychotics
Typical Antipsychotics cause extrapyramidal side effects (EPSE)
These can cause movement and muscle disorders which can be extremely distressing for the patient, often manifesting in symptoms similar to Parkinson’s disease.
Long term use can cause Tardive Dyskenesia, a movement disorder affecting face, neck and trunk of the body
Other common side-effects of typical anti-psychotics
Other side effects include;
- Dry mouth
- Constipation
- Photosensitivy
- Blurred vision
Most side effects, including EPSE can now be treated with other medications with anti cholinergic properties (Benztropine).
A-typical anti-psychotics
Second generation antipsychotics are know as a-typical.
Their action is similar to typical psychotics but more specific to dopamine 2 receptors (a subset of receptors most involved with psychotic symptoms) and also act on serotonin, which is associated with mood and logical thinking.
This improves the adverse side effect profile
Side-effects of A-typical anti-psychotics
No other a-typical anti-psychotics cause agranulocytosis, however they do still cause significant side-effects including:
Weight gain
Insulin dysregulation
Loss of libido and sexual functioning
However, they are usually tolerated much better than the their first generation cousins, and extensively used in the contemporary management of schizophrenia and psychosis.
Clozapine
The first a-typical developed was Clozapine.
Clozapine has the most complex, but effective binding properties of any other anti-psychotic drug.
Unfortunately in 1% of users, it can also cause agranulocytosis, which if not detected early can compromise the immune system and lead to death.
For this reason, regular monitoring of neutrophil and lymphocytes is performed, and extra consideration is given when commencing the drug.
Clozapine is often effectively used when a person is unresponsive to any other medication.
The anti-psychotic depot injection
A depot injection is a slow-release form of antipsychotic medication.
Originally developed for slow release of typicals in an oil based solution.
Both Typical and A typical available as depot injections
Given as a deep intramuscular injection
Lasts for 2-4 weeks, commonly administered fortnightly.
Mood Stabilizers
Mood stabilizers are used to treat affective disorders such as BPAD, and mania.
Lithium
Is a mood stabiliser
Lithium is a naturally occurring salt and is extremely effective in treating BPAD.
The mechanism of action is not entirely understood, however Lithium is thought to act on serotonin and dopamine transmitters
Lithium has a very narrow therapeutic range, therefore regular monitoring of serum levels is required.
Toxicity can be life threatening, affecting CNS and commonly renal systems.
Anti-convulsants
Used as mood stabilisers
About 20 years ago, it was discovered that the use of anticonvulsants in high doses was also effective in the treatment of affective disorders.
Sodium-Valporate, Carbamazapine and Lamotrigine are now becoming mainstream.
Although still requiring monitoring of serum levels, these medications are less “toxic” and cause fewer side effects.
Stimulants
Because of the potential for addiction and abuse, stimulants are rarely used in mainstream psychiatry.
However amphetamines are still prescribed for narcolepsy in specialist settings
And amphetamine based medications such as Ritalin are used extensively in child and adolescent services for attention deficit disorders.
Mechanism of Action & common side effects of stimulants
Amphetamines inhibit the re-uptake of dopamine by effectively holding dopamine onto the receptor sites, stimulating them.
Increased stimulation of dopamine receptors at moderate levels is known to help with concentration and focus – hence the usefulness of Ritalin in attention deficit disorders.
Common side effects include: Nervousness, trouble sleeping, loss of appetite, weight loss, dizziness, nausea, vomiting, or headache.
