FACULTY OF HEALTH
Department of Community Health and Social Work
Learning Disability Division
PHARMACOLOGY IN LEARNING DISABILITIES NURSING
Resource Pack
Fiona Rich
Senior Lecturer
PHARMACOLOGY IN LEARNING DISABILITIES NURSING
INTRODUCTION
There are a number of main groups of drugs used in learning disability nursing.
These groups of drugs are generally used to help people with learning
disabilities lead a more independent life or to cope more effectively in society.
GROUP 1 – ANTICONVULSANT DRUGS
Epilepsy
Epilepsy is characterised by the following:
 Sensory disturbances - e.g. blurred vision
 Motor disturbances - e.g. thrashing limbs or stiffening of
limbs
 Autonomic disturbances - e.g. contraction of the bladder
leading to incontinence
 Changes in the level of consciousness
One in 20 people have a seizure of some sort in their life, however, in
order to constitute epilepsy, the seizures must recur. Epilepsy affects at
least 5 in every 1,000 people (i.e. - 1 in 200 have recurrent seizures.)
The frequency of epilepsy occurring in people with learning disabilities is
higher than average and increases in proportion with the severity of their
disability. About 30% of people with a learning disability also have some
form of epilepsy. The incidence increases in those who have severe
learning disability. At least 50% of people with severe learning disability
will have epilepsy (NSE 1996)
Changes in Brain Activity
Normally there is a relatively low level of electrical activity within the
brain. It is known that those who suffer from epilepsy have a loss of
inhibitory cells, i.e. that there is an inability to switch off cells once they
have been stimulated – there is nothing to stop the cells from firing.
During an epileptic fit, excessive electrical activity builds up causing
uncontrolled stimulation of the brain. Excitatory cells fire in rhythmic,
uncontrolled bursts, which can spread from a localised area of the brain
to a generalised area, eventually involving the whole brain.
Anticonvulsant Drugs
Anticonvulsant drugs are used to reduce the risk of an epileptic fit or to
stop one that is in progress. Anticonvulsant drugs permit people who
have Epilepsy to lead a more independent life, reducing the possibility of
brain damage that can result from recurrent seizures.
Anti-convulsant drugs have an inhibitory effect, which neutralises
excessive electrical activity in the brain – the drugs inhibit the electrical
impulses thereby changing the levels of neurotransmitters in the brain.
[See appendix 1]
Examples of Drugs Used
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Carbamazepine
Clobazam
Clonazepam
Diazepam (Rectal)
Ethosuximide
Gabapentin
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Lamotrigine
Phenobarbitone
Phenytoin
Sodium Valporate
Topiramate
Vigabatrin
Recognising Anti-epileptic Drugs
(Not to scale)
Common Side Effects
 Like most drugs working on the Central Nervous System, drowsiness is
often noted. Phenobarbitone causes the most drowsiness.
 Phenytoin is known for coarsening facial features, causing hirsuteness
(excessive hair) and hypertrophy of the gums.
 Sodium Valporate is irritant to the intestine and causes transient hair loss
and some liver damage.
 Carbamazepine causes a rash with 3% of users
 Phenytoin and Carbamazepine are liver enzyme inducers, which means that
they sometimes interfere with how other drugs are used in the body, and it is
also the reason why they have to be introduced gradually
 Long term use of some anti-convulsants has caused depletion of folic acid
and problems with Vitamin D metabolism.
 If users exhibit Ataxia or slurred speech, this indicates a toxic level in the
blood
GROUP 2 – ANTIPSYCHOTICS
Psychosis
Psychosis is a term used to describe mental disorders that prevent the
person from thinking clearly, recognising reality and acting rationally.
These disorders include:
 Schizophrenia
 Manic Depression
 Paranoia
There have been various estimates of the incidence of mental illness on
people with a learning disability. These range from 10% (Heaton Ward,
1984) to 60% (Jancar, 1988). It is difficult to compile statistics on the
prevalence of mental illness in learning disabilities because diagnosis is
problematic due to communication difficulties. Mental Illness in learning
disabilities may take the following forms:
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Severe challenging behaviour
Anxiety States
Manic Depression
Obsessional Neurosis
Antipsychotic Drugs
The aim of this drug treatment is to calm the clients without making them
too drowsy to function so that they may lead a more independent life.
Action of Antipsychotic Drugs
Brain activity is partly governed by the action of Dopamine, which
transmits signals between brain cells. In psychotic illness, the brain cells
release too much dopamine, causing excessive stimulation. Dopamine is
said to be the cause of hallucinations. Antipsychotic drugs help reduce
the adverse effects of excess dopamine. [See appendix 2]
Examples of Antipsychotics used
1. Phenothiazine Anti-psychotics
Ø Chlorpromazine
Ø Thioridazine
Ø Trifluoperazine
2. Butyrophenone Anti-psychotics
Ø Haloperidol
Common Side Effects
1. Extra Pyramidal Side effects – The extra pyramidal tract contains the
motor nerves which commence at the Basal Ganglia. Its main function
is to co-ordinate steady movement. Because the amount of dopamine
is reduce, it also reduces the amount of dopamine in the Basal
Ganglia, causing the following symptoms:
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Tremor, rigidity (Parkinson-like symptoms)
Motor restlessness (Akathisia)
Facial Twitch
Arching of back
Lock jaw
Occulogyric Crisis
2. Tardive Dyskinesia – May develop one to five years after taking
antipsychotics. Consists of repeated jerking movements of the mouth,
tongue and face and sometimes the hands and feet. This is an
irreversible side effect.
3. Anti-cholinergic Effects
 Dry mouth
 Blurred vision
 Constipation
4. Weight Gain
Effects of Sudden Withdrawal
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Nausea
Vomiting
Sweating
Headache
Restlessness
GROUP 3 – ANTICHOLIERGIC DRUGS
Action of Anticholinergic Drugs
Normal movement depends on a balance between Dopamine and
Acetylcholine (neurotransmitters). When anti-psychotic drugs reduce the
amount of dopamine, the balance is disturbed – there is over activity of
Acetylcholine.
Anticholinergic drugs occupy the receptors and displace Acetylcholine,
therefore the normal balance is restored. [see appendix 3]
Examples of Drugs Used
 Procyclidine
 Orphenadrine
 Benzhexol
Properties of Acetylcholine
1. Stimulation of Parasympathetic Nervous System
Area Affected
Pupil
Heart Rate
Bronchial Muscle
Stomach Secretions
Intestinal Juices
Saliva
Bladder Muscle
Bladder Sphincter
Effect of Stimulation
Contracted
Decreased
Contracted
Increased
Increased
Increased
Contracted
Relaxed
2. Stimulation of Autonomic Ganglia
Area Affected
Stomach
Intestines
Heart Rate
Blood Pressure
Saliva
Water
Effect of Stimulation
Motility increase
Motility increase
Decrease
Rise
Increase
Retention
Common Side Effects
The effects of Acetylcholine noted above are reduced in the body
because of the reduction in Acetylcholine. Side effects therefore occur
which are opposite to the properties of Acetylcholine:
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Blurred vision - due to dilated pupils
Tachycardia - due to increased heart rate
Gastro-intestinal disturbances - due to motility decrease
Dry Mouth - due to reduction in saliva
Retention of Urine - due to contraction of Bladder Sphincter
Other side effects include:
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Hypersensitivity
Confusion
Nervousness
Excitement
Dizziness
Psychiatric Disturbances
GROUP 4 – ANTIDEPRESSANTS
Depression
Depression is thought to be caused by a reduction in the level of certain
excitatory neurotransmitters that affect mood by stimulating brain cells.
Antidepressants increase the level of excitatory neurotransmitters, and
are used to relieve a state of endogenous or reactive depression.
[appendix 4]
Types of Antidepressant
1. Tricyclic agents
 Amitriptyline
 Imipramine
When excitatory neurotransmitters are released by brain cells, they are
normally rapidly taken up again by the cells. Tricyclic agents block this
re-uptake, thus increasing the level of excitatory neurotransmitters
outside of the cell, prolonging the stimulating effect on the brain. [see
appendix 5]
Risks and Precautions
 can produce coma
 can cause fits (due to an increase in excitatory stimulation)
 Can disturb heart rhythm
2. Monoamine Oxidase Inhibitors (MAOI's)
These drugs block the action of the enzyme that normally breaks
down the excitatory neurotransmitters.
MAOI's allow the
neurotransmitters to build up to a high level and produce a greater
stimulation of the brain. [see appendix 6]
Risks and Precautions
 can cause fits (due to an increase in excitatory stimulation)
 can de-activate enzymes in the body that normally break down
chemicals, particularly Tyramine
 MAOI's taken with foods rich in Tyramine (cheese, meat, yeast
extracts, red wine) can produce a dramatic rise in blood pressure
(Tyramine has a similar affect to adrenaline, which raises blood
pressure)
3. Selective Serotonin Re-uptake Inhibitors (SSRI's)
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Fluoxetine (Prozac)
The serotonin uptake inhibitors are a new class of antidepressants which block the uptake of the excitatory
neurotransmitter serotonin, and do not have many of the side
effects of the tricyclic and MAOI anti-depressant drugs.
Side Effects Common to all groups
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Anti-cholinergic effects
Toxic cardiac effects
Weight gain
Drowsiness
GROUP 5 – MUSCLE RELAXANTS
Muscle spasm is an involuntary, painful contraction of a muscle or a group of
muscles that can stiffen a limb or back. Spacticity is another form of muscle
tightness seen in some neurological disorders such as multiple sclerosis, stroke
or cerebral palsy. Drugs can be used to relieve the symptoms.
In Spasticity, the sufferer's legs may become so stiff and uncontrollable that it is
impossible for them to walk unaided. Drugs can help relieve the symptoms
without taking all the strength away. Relaxation of the muscles often permits
physiotherapy to be given for longer term relief.
Action of Muscle Relaxants
Muscle relaxant drugs work in one of 2 ways:
Centrally acting drugs damp down the passage of the nerve signals from the
brain and spinal cord that cause muscles to contract, thus reducing excessive
stimulation of muscles and unwanted muscular contraction. [see appendix 7]
Centrally-acting muscle relaxants restrict the passage of nerve signals to the
muscles by occupying a proportion of the receptors in the central nervous
system that are normally used by chemical neurotransmitters to transmit such
impulses. Reduced nervous stimulation allows the muscles to relax.
Other drugs (such as Dantrolene) reduce the sensitivity of the muscles to the
nerve signals.
Examples of drugs used
Centrally-acting drugs
 Baclofen
 Tizanidine
 Diazepam
Others
 Dantrolene
 Quinine
Side Effects
most centrally-acting drugs can have a generally depressant effect on nervous
activity and produce drowsiness, particularly at the beginning of the treatment.
Too high a dosage can excessively reduce the muscles' ability to contract and
therefore can cause weakness
Risks
Dependency on the drug for depressing the excessive nervous activity
responsible for muscle spasm.
Sudden withdrawal causes stiffness
ACTIVITY
Discuss the medication likely to be prescribed for the following people:
Jane, who has quadriplegia, spastic paralysis and generalised tonicclonic seizures which at present are uncontrolled. She is 30 years old,
but has the stature and size of a 10 year old child
Adam, an elderly gentleman who has muscle spasm following a stroke
and also suffers from depression
Ben, who suffers from a right-sided hemiplegia (spastic paralysis) and
psychosis. Ben is also clinically obese.
You are required to consider:
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the dose
the route of administration
side effects
contra-indications and risks of the drug
Please refer to the BNF and other guides to medicines and drugs as necessary
You will be required to feedback this information in the feedback session
identified on the module timetable