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Antidepressants drugs are drugs that can help with depression, social anxiety, anxiety disorders, seasonal affective disorder, dysthymia, or mild persistent depression, among other things. They attempt to fix chemical imbalances in the brain's neurotransmitters, which are known to be the cause of mood and behavior abnormalities.
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Keyterms: Antidepressants, Drgs, Depression, Social anxiety, Anxiety disorders, Seasonal affective disorder, Dysthymia, Mild persistent depression, Neurotransmitters, Compounds
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What are Drugs?
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Drugs are compounds with a low molecular mass that interact with macromolecular targets in the body and cause a biological reaction. Depending on their composition, dosage, and method of administration, they produce these effects. Some of them are made up of a single active ingredient, while others are made up of a combination of compounds. The ingredients can be synthesized chemically or biologically.
Medicines
Medicines are chemicals that are used in the diagnosis, prevention, and treatment of diseases. Most drugs used as medicines can be poisonous if used in higher dosages than those prescribed. Chemotherapy is the use of chemicals for therapeutic purposes.
Classes of Drugs
Drugs can be classified into the following classes:
- Antacids
- Antihistamines
- Tranquilizers or Antidrepressants
- Analgesics
- Antimicrobials
- Antifertility Drugs
Antidepressant drugs fall under the class of Tranquilizers.
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Tranquilizers
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Tranquilizers are medications that work on the nervous system. These have an impact on the nerve-to-receptor message transmission process. Tranquilizers are a class of pharmacological substances that are used to alleviate stress as well as mild to severe mental illnesses.
Tranquilizers are used in Sleeping pills
They give a person a sense of well-being, relieving him of stress, tension, anxiety, and irritation. They are one of the most important ingredients in sleeping medicines. There are numerous different forms of tranquilizers, each with its own set of functions.
Noradrenaline, for example, is a tranquilizer that helps to improve mood. When noradrenaline levels are low, signaling activity is likewise reduced, making a person feel depressed. Antidepressant medications or a tranquilizer can be utilized in these instances.
Noradrenaline Structure
The enzymes that catalyze the breakdown of noradrenaline are inhibited by these medications. Noradrenaline is slowly degraded when the enzymes are stopped, so it activates its receptors for a longer period of time, counteracting the depressive impact.
Classification of Tranquilizers
Tranquilizers are classified into,
- Minor Tranquilizers and
- Major Tranquilizers
Minor Tranquilizers: Minor Tranquilizers, often known as anxiolytics, are sedatives and anxiety relievers. These compounds are now known as anti-anxiety meds.
Types of Tranquilizers
Major Tranquilizers: Major Tranquilizers, also known as neuroleptics, were created to treat psychiatric conditions such as schizophrenia. These sedatives are used to treat hallucinations and other types of delusions. Tranquilizers such as phenothiazines, butyrophenones, thioxanthenes, rauwolfia alkaloids, and clozapine are commonly recommended for long periods of time.
Drug abuse causes mood melancholy
Tranquilizers, like all other medications, have the potential to cause negative effects, even when taken in prescribed amounts. Mild tranquilizers at lower doses can cause drowsiness and a loss of coordination that resembles drunkenness. These reactions are more common when the patient first starts taking the medicine, but they become more common as the medication accumulates. The use of Tranquilizers over an extended period of time can cause serious mood melancholy.
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Antidepressant Drugs as Tranquilizers
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When noradrenaline levels are low for any cause, signal-sending activity is reduced, and the person feels depressed. Antidepressant medications are essential in such instances.
The enzymes that catalyze the breakdown of noradrenaline are inhibited by these medications. When the enzyme is blocked, the key neurotransmitter is slowly metabolized and can activate its receptor for prolonged periods of time, counteracting the depressive effect.
Iproniazid and phenelzine are two examples of such medications. Some tranquilizers, such as chlordiazepoxide and meprobamate, are mild tranquilizers that can help to relax. Equanil is a drug that is used to treat depression and hypertension.
Antidepressant
Barbituric acid derivatives, such as Veronal, Amytal, Nembutal, Luminal, and Seconal, form a significant class of tranquilizers. Barbiturates are the name for these derivatives. Barbiturates are hypnotic (sleep-inducing) drugs. Valium and serotonin are two more tranquilizers that are commonly utilized.
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Types of Antidepressant Drugs
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Antidepressants are classified into five categories:
Serotonin and noradrenaline reuptake inhibitors (SNRIs)
Major depression, mood disorders, attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety disorders, menopausal symptoms, fibromyalgia, and chronic neuropathic pain are all treated with serotonin and noradrenaline reuptake inhibitors (SNRIs).
SNRI Mechanism of Action
Some examples are:
- duloxetine (Cymbalta)
- Venlafaxine (Effexor)
- desvenlafaxine (Pristiq)
SSRIs (selective serotonin reuptake inhibitors)
They are effective antidepressants. The most well-known drugs in this class are clomipramine, fluoxetine (Prozac), sertraline, and paroxetine.
Structure of SSRI Antidepressants
Examples include
- citalopram (Celexa)
- escitalopram (Lexapro)
- fluoxetine (Prozac, Sarafem)
- fluvoxamine (Luvox)
Tricyclic antidepressants (TCAs)
They are used to treat depression, fibromyalgia, few types of anxiety and chronic pain.
Structure of TCA Antidepressants
Examples include
- Amitriptyline (Elavil)
- Amoxapine- clomipramine (Anafranil)
- Desipramine (Norpramin), doxepin (Sinequan), imipramine (Tofranil), nortriptyline (Pamelor), protriptyline (Vivactil) and trimipramine (Surmontil).
Monoamine oxidase inhibitors (MAOIs)
Before the emergence of SSRIs and SNRIs, this antidepressant was extensively prescribed for pain.
Examples of MAOIs include
- Phenelzine (Nardil)
- Tranylcypromine (Parnate)
- Isocarboxazid (Marplan)
- Selegiline (EMSAM, Eldepryl)
Structure of MAO Antidepressants
Noradrenaline and specific serotoninergic antidepressants (NASSAs)
Anxiety disorders, several personality disorders, and depression are all treated with these.
Examples include
- Mianserin (Tolvon)
- Mirtazapine (Remeron, Avanza, Zispin).
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Side Effects of Antidepressant Drugs
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Common effects are nausea and anxiety, but this will depend on the type of drug used. Some of the side effects are:
- Anxiety
- Dizziness
- Nightmares or vivid dreams
- Electric shock-like sensations in the body
- Flu-like symptoms
- Abdominal pain
Effects of Antidepressants
Things to Remember
- Drugs are compounds with a low molecular mass that interact with macromolecular targets in the body and cause a biological reaction. Depending on their composition, dosage, and method of administration, they produce these effects.
- Antidepressants are a class of tranquilizers that includes antidepressants. Drugs that affect the nervous system are known as tranquilizers. They have an impact on the passage of messages from nerves to receptors. Anti-anxiety drugs are another name for them.
- Antidepressants are classified into five categories. Serotonin and noradrenaline reuptake inhibitors (SNRIs), selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants, Monoamine oxidase inhibitors (MAOIs), and Noradrenaline and specific serotoninergic antidepressants (NASSAs) are the different types of antidepressants.
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Sample Questions
Ques. What are drugs? What is its classification? [3 marks]
Ans. Drugs are low molecular mass substances that interact with macromolecular targets in the body and produce a biological response. They render these effects depending on their composition, dosage, and route of administration.
Classification of drugs are:
- On the basis of pharmacological effect
- On the basis of drug action
- On the basis of chemical structure
- On the basis of molecular targets
Ques. What are Tranquilizers? Give two examples. [2 marks]
Ans. Tranquilizers are chemical compounds used for the treatment of stress and mild or even severe mental diseases. Example: Equanil, meprobamate
Ques. Which class of drugs is used in sleeping pills? [2 marks]
Ans. Tranquilizers like barbiturates are used in sleeping pills.
Ques. What are monoamine oxidase inhibitors? Give examples. [3 marks]
Ans. Monoamine oxidase inhibitors inhibit the action of monoamine oxidase, a brain enzyme. Monoamine oxidase helps break down neurotransmitters, such as serotonin. This type of antidepressant was commonly prescribed before the introduction of SSRIs and SNRIs.
Examples of MAOIs include phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan) and selegiline (EMSAM, Eldepryl).
Ques. What are analgesic medicines? How are they classified and when are they commonly recommended for use? [2 marks]
Ans. Analgesic medicines are drugs that reduce or abolish pain without causing reduction of consciousness, mental confusion, incoordination or paralysis or some other disorder of the nervous system are called analgesic medicines.
They are classified into the following two categories :
- Non-narcotic (non-addictive) drugs Example: Aspirin, Ibuprofen
- Narcotic (addictive) drugs Example: Morphine, Heroin.
They are recommended with proper prescription because they are habit forming drugs
Ques. What are some of the side effects of antidepressants? [2 marks]
Ans. Common effects are nausea and anxiety, but this will depend on the type of drug used. Some of the side effects are:
- Anxiety
- Dizziness
- Nightmares or vivid dreams
- Electric shock-like sensations in the body
- Flu-like symptoms
- Abdominal pain
Ques. Why do we need to classify drugs in different ways? [3 marks]
Ans. Drugs are classified in the following different ways:
- Based on pharmacological effect.
- Based on action on a particular biochemical process.
- Based on chemical structure.
- Based on molecular targets.
Each classification has its own usefulness.
- Classification based on pharmacological effect is useful for doctors because it provides them the whole range of drugs available for the treatment of a particular disease.
- Classification based on action on a particular biochemical proc*ess is useful for choosing the correct compound for designing the synthesis of the desired drug.
- Classification based on chemical structure helps us to design the synthesis of a number of structurally similar compounds having different substituents and then choosing the drug having the least toxicity.
- Classification on the basis of molecular targets is useful for medical chemists so that they can design a drug which is most effective for a particular receptor site.
Ques. Why the medicines should not be taken without consulting doctors? [2 marks]
Ans. No doubt medicines are a panacea for most of body ailments. But their wrong choice and overdose can cause havoc and may even prove to be fatal. Therefore, it is of utmost importance that medicines should not be given without consulting doctors.
Ques. Antacids and antiallergic drugs interfere with the function of histamines but do not interfere with the function of each other. Explain. [2 marks]
Ans. They do not interfere with the functioning of each other because they work on different receptors in the body. Histamine stimulates the secretion of pepsin and hydrochloric acid in the stomach. The drug cimetidine (antacid) was designed to prevent the interaction of histamine with the receptors present in the stomach wall. This resulted in the release of a lesser amount of acid. Antacid and antiallergic drugs work on different receptors.
Ques. A low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem? Name two drugs. [2 marks]
Ans. In case of a low level of the neurotransmitter, noradrenaline, tranquilizer (antidepressant) drugs are required because low levels of noradrenaline lead to depression. These drugs inhibit the enzymes which catalyze the degradation of noradrenaline. If the enzyme is inhibited, noradrenaline is slowly metabolized and can activate its receptor for longer periods of time thereby reducing depression. Two important drugs are iproniazid and phenelzine.
Ques. How do antiseptics differ from disinfectants? Give one example of each. [3 marks]
Ans. Many times, the same substance can act as an antiseptic as well as a disinfectant by changing the concentration of the solution used. For example, a 0.2 percent solution of phenol acts as an antiseptic and its 1 percent solution is a disinfectant. Chlorine is used in India for making water fit for drinking at a concentration of 0.2 to 0.4 ppm (parts per million). A low concentration of sulphur dioxide is used for sterilizing squashes for preservation. A few points of distinction between antiseptics and disinfectants are listed.
| Antiseptics | Disinfectants |
|---|---|
| Can kill or prevent the growth of micro-organisms. | Can kill micro-organisms. |
| Do not harm the living tissues. Therefore, these can be applied to the skin. | Toxic to the living tissues. Therefore, these cannot be applied to the skin. |
| These are used for the dressing of wounds, ulcers and in the treatment of diseased skin. | These are used for disinfecting floors, toilets, drains, instruments etc. |
Ques. Explain the following as used in medicinal chemistry [3 marks]
Lead compounds
Target molecules or drug targets.
Ans.
- Lead compounds are the compounds that are effective in different drugs. They have specific chemical formulas and may be extracted either from natural sources (plants and animals) or may be synthesised in the laboratory.
- Target molecules or drug targets. An enzyme (E) functions by combining with the reactant (called a substrate) denoted as ‘S’ to form an activated complex known as the enzyme-substrate complex (E-S). The complex dissociates to form a product and releases the enzyme for carrying out further activity.
E + S → [E – S] → P + E
Complex
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