Drugs that affect psychic function, behaviour, experience or mental symptoms are called psychotropic and psychoactive dugs.
Terms :-
Agonist – Drug that activates receptor.
Antagonist – Drug that blocks receptor.
Drug – Acc. To WHO, A drug is any substance that, when taken into living organism may modify one or more of its functions.
Psycho-pharmacology – a branch of science which deals in the study of drugs which are used in the treatment of psychotic disorders / mental illness.
Classification of psycho-tropic drugs.
Psychotropic drugs are classified into following groups-
- Anti depressant drugs
- Anti psychotic drugs
- Anti anxiety or sedative hypotonic drugs
- Mood stabiliser drugs
- Miscellaneous drugs.
Anti depressant drugs
Anti depressant drugs also called mood elevator or thymoleptic drugs.
1st anti depressant drug ‘Imipramine’ discovered by Thomas Kohn in 1958
Indication :-
Used in all kind of depression and grief (the emotion that follows the loss of a loved person or thing)
Mechanism of action :-
- It increases extracellulair neurotransmitter (serotonin & nor epinephrine) level in to body.
- These neurotransmitter elevate the mood of patient.
- Reuptake inhibitor drugs block reuptake (reuptake is the process of neurotransmitter inactivation in to pre-synaptic neurons) of neurotransmitter, thus resulting in elevated level of extracellulair neurotransmitter at synapses for longer period.
Classification –
Antidepressant drugs are divided into following classes –
- Tricycles antidepressant (TCA) or monoamine reuptake inhibitors (MARIs)
These are named after their 3 ring structure (these blocks the reuptake of norepinephrine)
Examples are imipramine, clomipramine, trimipramine, desipramine, protriptyline, nortriptyline, amitriptyline, doxepine.
Side effects of TCA / MARIs
- Dry mouth
- Orthostatic hypotension
- Palpitation
- Tachycardia
- Blurred vision
- Urinary retention
- Constipation
- Seizures
- Sedation
- Weight gain
- Cardiovascular dysfunction (dysrhythmias)
- Ejaculation and erection disturbance.
- Selective serotonin reuptake inhibitor ( SSRI)
- These drugs inhibit reuptake of only serotonin by pre-synaptic neuron, so increase level of serotonin in synapses, elevates the mood of patient.
- It is most widely used class of antidepressant.
- Examples are fluoxetine, fluvoxamine, paroxetine, sertraline, citalopram, escitalopram.
Side effects of SSRIs
- Nausea, vomiting
- Diarrhoea
- Dry mouth
- Headache
- Nervousness
- Dizziness
- Apathy
- Tremor
- Seizure activities
- Priapism
- Sexual dysfunction
- Mono-amine oxidase inhibitor ( MAOI)
- Mono-amine oxidase (MAO) is an enzyme which inactivate neurotransmitters (norepinephrine & Serotonin)
- So by inhibiting MAO enzyme synthesis, Level of neurotransmitters increase in to Body which causes elevated mood.
- Examples are selegiline, phenelzine, isocarboxazid.
- Avoid food containing tyramine (an intermediate product in the conversion of tyrosine to epinephrine) because it may cause hypertensive crisis.
- Use phentolamine as an antidote in hypertensive crisis caused by MAOIs.
Side effects of MAOIs
- Dry mouth
- Orthostatic hypotension
- Palpitation
- Tachycardia
- Blurred vision
- Urinary retention
- Constipation
- Delay in ejaculation
- Peripheral oedema
- CNS stimulation
- Hypertensive crisis
- Occipital headache constricting chest pain
- Neck stiffness
- Soreness
- Novel compound or atypical anti-depressant :-
- These are newer anti-depressant drugs.
- Examples are trazodone, nefazodone, duloxetine.
Nurses role :-
- Advice the patient that medicine onset time is 2-4 week.
- Advice the patient that medicine should be taken with meal or after meal.
- Avoid alcohol and driving.
- Avoid anti-acid medication.
- Advice the patient to stay in bed for few minutes before getting out form the bed.
- Does not stop the medicines immediately or without advice.
- Caution the patient about photosensitivity and Advice to prevent sun exposure.
Note:-
- As drugs begin to start their effect, level of energy of the patient increase so patient can execute plan of suïcide if he/she have, so be careful after starting antidepressant.
- Tricyclic Antidepressant (TCA) can cause cardiac toxicity (tachycardia, dysrhythmia, heart block and ventricular fibrillation) and monoamine oxidase inhibitor (MAOIs) cause hypertensive crisis (severity increase in the liver disorder) so nurse should take precaution while administering antidepressant to patient with cardiovascular and liver disorder.