Learn Pharmacology Using Classes Clinical Placement Guide

By Dr Yangama Jokwiro

Pharmacology Short Notes: Mechanism of action of drugs: Drug Classes: Placement and examination guide: Nursing Students: Medical Students: Allied Health Students

• Language: English
• Publisher: Yangama
• Release date: Dec 5, 2023
• ISBN: 9780645633894

Book preview

5-ALPHA-REDUCTASE INHIBITORS

ANTIANDROGEN

Mechanism of Action

5-alpha-reductase inhibitors are a class of drugs that inhibit the activity of the enzyme 5-alpha-reductase, which is responsible for converting testosterone to dihydrotestosterone (DHT) in the body. By inhibiting this enzyme, these drugs reduce the levels of DHT in the body, which can have a number of therapeutic effects

Therapeutic use

The most well-known use of 5-alpha-reductase inhibitors is in the treatment of benign prostatic hyperplasia (BPH), a condition in which the prostate gland enlarges and obstructs the urinary tract. By reducing DHT levels, these drugs can help shrink the prostate gland and relieve the symptoms of BPH, such as urinary urgency and frequency. Another use of 5-alpha-reductase inhibitors is in the treatment of male pattern baldness. DHT is known to contribute to hair loss in men, and by reducing its levels, these drugs can help slow or even reverse the balding process.

Side Effects

They increase the risk of developing prostate cancer, decrease libido, causes erectile dysfunction and ejaculatory dysfunction, may cause infertility, breast tenderness, gynecomastia. They are also associated with depression, anxiety, self-harm, and dementia.

5-AMINOSALICYLATES

AMINO-SALICYLATES

ANTI-INFLAMMATORY

Mechanism of Action

The exact mechanism of action of 5-ASAs is not completely understood, but it is believed that they act locally on the inflamed tissues in the digestive tract. 5-ASAs are thought to block the production of pro-inflammatory chemicals and to stimulate the production of anti-inflammatory chemicals in the colon. There are several types of 5-ASAs available, including mesalamine, sulfasalazine, and olsalazine. Mesalamine is the most commonly used 5-ASA and is available in various formulations, such as oral tablets, capsules, enemas, and suppositories. Sulfasalazine and olsalazine are also available as oral tablets and capsules.

Therapeutic use

5-aminosalicylates (5-ASAs) are a class of anti-inflammatory drugs used to treat inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease. These drugs work by reducing inflammation in the colon and other parts of the digestive tract.

Side Effects

5-ASAs are generally well-tolerated, but they can cause side effects such as nausea, vomiting, diarrhea, and headache. Rarely, they can cause more serious side effects, such as liver or kidney damage.

5HT3 RECEPTOR ANTAGONISTS

ANTIEMETIC

Mechanism of action

5HT3 receptor antagonists, also known as serotonin 5HT3 receptor antagonists or simply 5HT3 antagonists, are a class of drugs that block the action of serotonin at the 5HT3 receptor. Serotonin is a neurotransmitter that is involved in regulation of mood, appetite, and sleep. In the digestive system, serotonin can stimulate the vomiting centre in the brain and cause nausea and vomiting.

Therapeutic use

5HT3 receptor antagonists are primarily used to prevent nausea and vomiting caused by chemotherapy, radiation therapy, and surgery. They are also sometimes used to treat nausea and vomiting associated with other conditions, such as migraine headaches and gastroenteritis. These drugs are available in various formulations, including oral tablets, oral dissolvable tablets, injections, and patches.

Side effects

5HT3 receptor antagonists are generally well-tolerated, but they can cause side effects such as headache, constipation, and fatigue. In rare cases, they can cause more serious side effects, such as changes in heart rhythm.

ACE INHIBITORS WITH CALCIUM CHANNEL BLOCKING DRUGS

ANTIHYPERTENSIVE

Mechanism of action

ACE inhibitors with calcium channel blocking drugs (CCBs) are a combination of two classes of drugs used to treat high blood pressure. ACE inhibitors work by inhibiting the production of angiotensin II, a hormone that constricts blood vessels and raises blood pressure. CCBs work by blocking the influx of calcium into muscle cells in blood vessels, which also causes them to relax and lowers blood pressure.

Therapeutic use

This combination therapy is generally well-tolerated and is often used when single-drug therapy is not effective in controlling blood pressure for people with hypertension.

Side effects

ACE inhibitors with CCBs can cause side effects, which may include dizziness, fatigue, headache, and low blood pressure.

ACE INHIBITORS WITH THIAZIDES

ANTIHYPERTENSIVE

Mechanism of action

ACE inhibitors with thiazides are a combination of two classes of drugs used to treat high blood pressure. ACE inhibitors work by inhibiting the production of angiotensin II, a hormone that constricts blood vessels and raises blood pressure. Thiazide diuretics work by increasing the excretion of sodium and water from the body, which also lowers blood pressure.

Therapeutic use

This combination therapy is generally well-tolerated and is often used when single-drug therapy is not effective in controlling blood pressure for people with hypertension

Side effects

ACE inhibitors with thiazides can cause side effects, which may include dizziness, fatigue, headache, and low blood pressure. Thiazides can also cause electrolyte imbalances, such as low levels of potassium, sodium, and magnesium, and can increase the risk of gout.

ADAMANTANE ANTIVIRALS

Mechanism of action

Adamantane antivirals are a class of antiviral drugs that are used to treat influenza A virus infections. They work by inhibiting the viral protein M2, which is necessary for the virus to replicate and spread. By blocking the function of M2, the virus is prevented from infecting new cells and replicating itself, which can help to reduce the severity and duration of the infection.

Therapeutic use

Adamantane antivirals are a class of antiviral drugs that are used to treat influenza A virus infections. In addition to their use in treating influenza A, amantadine has also been used to treat Parkinson's disease and drug-induced extrapyramidal symptoms, while rimantadine has been used to treat respiratory syncytial virus (RSV) infections.

Side effects

Common side effects may include nausea, vomiting, diarrhea, dizziness, and headache. More serious side effects, such as seizures, confusion, and psychiatric symptoms, may occur in rare cases.

ADRENAL CORTICAL STEROIDS

STEROIDAL ANTI-INFLAMMATORY DRUGS

Mechanism of action

Adrenal cortical steroids, also known as corticosteroids, are a class of hormones produced by the adrenal cortex, which is the outer layer of the adrenal gland. These hormones have a wide range of effects on the body, including regulating metabolism, reducing inflammation, and controlling the body's response to stress.

There are two main types of adrenal cortical steroids: glucocorticoids and mineralocorticoids. Glucocorticoids, such as cortisol, are involved in regulating metabolism and reducing inflammation. Mineralocorticoids, such as aldosterone, are involved in regulating electrolyte balance and blood pressure.

Glucocorticoids

Mineralocorticoids

Therapeutic use

Synthetic versions of these hormones, known as synthetic corticosteroids, are used in medicine to treat a variety of conditions, including inflammatory disorders, autoimmune diseases, and certain types of cancer. Corticosteroids can be taken orally, applied topically, or injected directly into the affected area. They are generally well-tolerated when used as prescribed, but can cause side effects, particularly with long-term use or high doses.

Side effects

Common side effects may include weight gain, mood changes, increased appetite, and fluid retention. Long-term use of corticosteroids can also lead to more serious side effects, such as osteoporosis, diabetes, and increased risk of infection.

ADRENAL CORTICOSTEROID INHIBITORS

Mechanism of action

Adrenal corticosteroid inhibitors are a class of drugs that work by blocking the production or actions of adrenal cortical steroids, which are hormones produced by the adrenal gland. They can be steroid synthesis inhibitors or steroid receptor antagonists.

Steroid synthesis inhibitors

Steroid receptor antagonists/abortion drug

Therapeutic use

Steroid synthesis inhibitors, such as ketoconazole and aminoglutethimide, work by blocking the production of adrenal cortical steroids, particularly cortisol. They are used to treat patients with Cushing syndrome and virilization caused by adrenal carcinoma. Steroid receptor antagonists, such as mifepristone, work by blocking the action of adrenal cortical steroids at the cellular level. Mifepristone (RU 486) is used to terminate the early part of a pregnancy.

Side effects

Common side effects of steroid synthesis inhibitors may include nausea, vomiting, and fatigue, while steroid receptor antagonists may cause menstrual changes, dizziness, and headache. In addition, long-term use of these drugs can lead to adrenal insufficiency, which is a condition in which the adrenal gland does not produce enough cortisol on its own. As such, these drugs are typically used for short periods of time.

ADRENERGIC BRONCHODILATORS

MECHANISM OF ACTION

Adrenergic bronchodilators are a class of drugs that are used to treat bronchial asthma and other respiratory conditions by relaxing the smooth muscles in the airways and improving breathing. These drugs work by activating beta-2 adrenergic receptors in the lungs, which leads to relaxation of the smooth muscle cells and dilation of the airways, making it easier to breathe. There are two main types of adrenergic bronchodilators: short-acting and long-acting. Short-acting bronchodilators are used to provide quick relief of symptoms during an asthma attack or other respiratory distress.

Long-acting bronchodilators are used to provide more sustained relief of symptoms and are often used in combination with other asthma medications, such as corticosteroids.

Therapeutic use

Adrenergic bronchodilators are used to treat and manage respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and bronchitis. They are administered by inhalation, injection, or oral tablet. Inhalation is the preferred route of administration for bronchodilators, as it allows for targeted delivery to the lungs with fewer systemic side effects. However, oral tablet formulations may be used for more severe cases or when inhalation is not possible.

Side effects

Common side effects may include tremors, nervousness, headache, and increased heart rate. More serious side effects, such as chest pain and difficulty breathing, may occur in rare cases.

ADRENERGIC UPTAKE INHIBITORS FOR ADHD

Mechanism of action

Adrenergic uptake inhibitors are a class of medications used to treat attention deficit hyperactivity disorder (ADHD). These drugs work by increasing the levels of norepinephrine and dopamine in the brain, which can improve attention, focus, and impulse control. There are two main types of adrenergic uptake inhibitors used for ADHD: methylphenidate and amphetamine derivatives. Methylphenidate, sold under brand names such as Ritalin and Concerta, is a mild stimulant that increases the levels of norepinephrine and dopamine in the brain by blocking their reuptake into nerve cells.

Amphetamine derivatives, such as Adderall and Vyvanse, also work by blocking the reuptake of norepinephrine and dopamine but are more potent and longer acting than methylphenidate.

Therapeutic use

Adrenergic uptake inhibitors for ADHD are typically taken orally, either as tablets or capsules. They may be taken once or twice daily, depending on the medication and the severity of symptoms.

Side effects

Common side effects may include insomnia, loss of appetite, and nervousness. More serious side effects, such as heart problems and hallucinations, may occur in rare cases.

ALDOSTERONE RECEPTOR ANTAGONISTS

DIURETIC

Mechanism of action

Aldosterone receptor antagonists are a class of medications that block the action of aldosterone, a hormone that regulates salt and water balance in the body. These drugs are used to treat several conditions, including heart failure, hypertension, and oedema.

The two most commonly used aldosterone receptor antagonists are spironolactone and eplerenone. These drugs work by binding to the aldosterone receptor and blocking the effects of aldosterone. This leads to an increase in the excretion of sodium and water and a decrease in potassium excretion.

Therapeutic use

Spironolactone is used primarily to treat hypertension and heart failure, while eplerenone is used primarily to treat hypertension and to reduce the risk of cardiovascular events in patients with heart failure after a heart attack.

Side effects

Aldosterone receptor antagonists can have several side effects, including hyperkalaemia (elevated potassium levels), gynecomastia (breast enlargement in men), and menstrual irregularities in women.

ALKYLATING DRUGS

ANTICANCER

CHEMOTHERAPEUTIC AGENTS

CHEMOTHERAPY

Mechanism of action

Alkylating drugs are a class of chemotherapy drugs that are used to treat cancer. These drugs work by attaching an alkyl group (a chemical structure consisting of carbon and hydrogen atoms) to the DNA of cancer cells, which damages their DNA and prevents them from dividing and growing.

Therapeutic use

Alkylating drugs can be used to treat a wide range of cancers, including leukemia, lymphoma, breast cancer, ovarian cancer, lung cancer, and multiple myeloma.

Side effects

These drugs can have significant side effects, including bone marrow suppression (which can lead to anaemia, infection, and bleeding), nausea and vomiting, hair loss, and an increased risk of developing other cancers. Some alkylating drugs, such as cyclophosphamide, can also cause bladder damage if not adequately flushed out of the body.

ALLERGENICS

ANTIALLERGY

Mechanism of action

Allergenics are a class of medications used to treat allergies. These medications work by exposing the body to small amounts of allergens, such as pollen, dust mites, or pet dander, in order to build up the body's immunity to these substances over time.

There are two main types of allergenics: immunotherapy and sublingual immunotherapy (SLIT). Immunotherapy involves receiving regular injections of allergens over a period of several months to several years, with the goal of desensitizing the body to the allergen. SLIT involves placing a tablet containing the allergen under the tongue, which is then absorbed by the body.

Therapeutic use

Allergenics can be effective in reducing allergy symptoms, including sneezing, runny nose, and itchy or watery eyes.

Side effects

Side effects, include local swelling and redness at the injection site or itching and irritation in the mouth and throat with SLIT.

ALPHA-ADRENORECEPTOR ANTAGONISTS

ALPHA-BLOCKERS

ANTIHYPERTENSIVE

Mechanism of action

These drugs work by blocking the action of adrenaline and noradrenaline on the alpha-adrenergic receptors, which leads to relaxation of smooth muscles in blood vessels and in the prostate gland. This results in increased blood flow and reduced pressure in the blood vessels, as well as decreased symptoms of BPH, such as urinary frequency and urgency.

Therapeutic use

Alpha-adrenoreceptor antagonists (alpha-blockers) are used to treat various conditions, including high blood pressure, benign prostatic hyperplasia (BPH), and Raynaud's disease. Tamsulosin is a more selective alpha-blocker that is often used specifically for BPH and has fewer cardiovascular side effects.

Side effects

These medications can have side effects such as dizziness, light-headedness, fatigue, and orthostatic hypotension (a drop-in blood pressure when standing up from a sitting or lying position).

ALPHA-GLUCOSIDASE INHIBITORS

ANTIDIABETIC

ORAL HYPOGLYCEMICS

Mechanism of action

Alpha-glucosidase inhibitors are a class of medications used to treat type 2 diabetes by slowing down the digestion of carbohydrates in the small intestine. These drugs work by inhibiting the action of alpha-glucosidase enzymes, which are responsible for breaking down carbohydrates into glucose. By slowing down carbohydrate digestion, alpha-glucosidase inhibitors can help regulate blood sugar levels and reduce the risk of hyperglycaemia (high blood sugar).

Therapeutic use

They are used in the treatment of diabetes mellitus. They are not typically used as a first-line treatment for type 2 diabetes but may be used in combination with other medications such as metformin or insulin.

Side effects

These medications are taken orally with meals, and can cause side effects such as bloating, gas, and diarrhea due to undigested carbohydrates passing through the intestines.

AMOEBICIDES

ANTI-AMOEBA

ANTIBIOTIC

Amoebicides are medications used to treat infections caused by amoebae, which are single-celled parasites that can infect humans and animals. These infections can range from mild to severe, and may affect the intestines, liver, or other organs.

There are several classes of amebicides, including nitroimidazoles, luminal drugs, and tissue drugs. Nitroimidazoles such as metronidazole and tinidazole are commonly used to treat intestinal and liver infections caused by amoebae. Luminal drugs such as paromomycin are used to treat intestinal infections, while tissue drugs such as chloroquine and primaquine are used to treat infections that have spread to other parts of the body.

Amebicides can have side effects such as nausea, vomiting, diarrhea, and headache. Some medications, such as metronidazole, should not be taken with alcohol due to the risk of a disulfiram-like reaction, which can cause severe nausea and vomiting. In some cases, prolonged or repeated use of amebicides can lead to drug-resistant infections.

AMINOGLYCOSIDES

ANTIBIOTIC

Mechanism of action

Aminoglycosides are a class of antibiotics used to treat bacterial infections. These drugs work by binding to the bacterial ribosome, preventing the bacteria from synthesizing proteins necessary for their growth and reproduction.

Therapeutic use

Aminoglycosides are effective against a wide range of gram-negative and some gram-positive bacteria. These medications are typically administered intravenously or intramuscularly and are often reserved for serious infections that are resistant to other antibiotics.

Side effects

Aminoglycosides can have side effects, including kidney damage, hearing loss, and damage to the vestibular system (which controls balance). Aminoglycosides should not be used during pregnancy or in breastfeeding mothers. Regular monitoring of kidney function and hearing is also important during treatment with aminoglycosides.

AMINOPENICILLINS

ANTIBIOTIC

Mechanism of action

Aminopenicillins are a type of beta-lactam antibiotic that is effective against a wide range of gram-positive and gram-negative bacteria. They are a subclass of the penicillin family and are structurally similar to penicillin G. These drugs work by inhibiting the synthesis of bacterial cell walls, leading to bacterial death.

Therapeutic use

Aminopenicillins are used to treat a variety of bacterial infections, including respiratory tract infections, urinary tract infections, and skin infections. They may also be used to treat certain types of sexually transmitted infections, such as gonorrhoea.

Side effects

Aminopenicillins can have side effects, including allergic reactions, gastrointestinal symptoms such as nausea and diarrhea, and skin rashes. Patients who have a history of allergic reactions to penicillin should not take aminopenicillins.

AMPA RECEPTOR ANTAGONISTS

Mechanism of action

AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor antagonists are a class of drugs that block the action of glutamate on the AMPA receptor. The AMPA receptor is a type of ionotropic glutamate receptor that is important in the transmission of signals in the brain.

Therapeutic use

AMPA receptor antagonists are used to treat a variety of neurological and psychiatric conditions, including epilepsy, neuropathic pain, and anxiety disorders. By blocking the action of glutamate on the AMPA receptor, these drugs can reduce neuronal excitability and improve symptoms associated with these conditions.

Side effects

These medications can have side effects, including dizziness, nausea, and fatigue. In rare cases, they may cause more serious side effects, such as seizures or psychiatric symptoms.

AMYLIN ANALOGS

ANTIDIABETIC

Mechanism of action

Amylin analogs are a class of drugs used to treat type 1 and type 2 diabetes. Amylin is a hormone that is normally produced by the beta cells of the pancreas, along with insulin. It helps regulate blood sugar levels by slowing the rate at which food is absorbed from the stomach and by suppressing the release of glucose from the liver. Amylin analogs are designed to mimic the action of natural amylin.

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Therapeutic use

They are usually administered as an injection, along with insulin, and can help control postprandial blood glucose levels in people with diabetes.

Side effects

Amylin analogs can have side effects, including nausea, vomiting, and decreased appetite. They may also increase the risk of hypoglycaemia when used with insulin.

ANDROGENS

TESTOSTERONE

Androgens are a class of hormones that are primarily responsible for the development and maintenance of male secondary sexual characteristics. The main androgen is testosterone, which is produced by the testes in men and in smaller amounts by the ovaries in women and the adrenal glands in both sexes.

Androgens are involved in a number of physiological processes, including the development of muscle mass and bone density, the growth of facial and body hair, and the deepening of the voice during puberty. They also play a role in the maintenance of sexual function and libido in both men and women.

In addition to their natural production, androgens can also be used as medications to treat conditions such as hypogonadism (low testosterone levels), delayed puberty, and certain types of breast cancer. Androgens can have side effects, including acne, hair loss, and an increased risk of prostate cancer in men.

ANABOLIC STEROIDS

ANABOLIC TESTOSTERONE

Anabolic steroids are synthetic variations of the male sex hormone testosterone. These drugs are typically used to enhance muscle growth, increase strength, and improve athletic performance. Anabolic steroids work by increasing protein synthesis in muscle cells, which leads to an increase in muscle size and strength. They can also decrease the amount of time it takes for muscles to recover after a workout, allowing for more frequent and intense training sessions.

They can have a number of side effects, including acne, hair loss, mood swings, and an increased risk of heart disease and liver damage. They can also cause a number of physical changes in both men and women, including the development of breast tissue in men and the growth of facial hair and a deepening of the voice in women.

Anabolic steroids are classified as controlled substances in many countries and are illegal to use without a prescription. They are often abused by athletes and bodybuilders who are seeking to gain a competitive edge or to improve their physical appearance.

Analgesic

Paracetamol

Trade names are Panadol, Panadol osteo. They may have different quantities of paracetamol.

Mechanism of action

Selectively inhibit Cyclooxygenases (COX) activities in the brain, which may contribute to its ability to treat fever and pain (it has no effect on the periphery unlike Non-steroidal ant--inflammatory drugs (NSAIDs) which means it’s not anti-inflammatory)

Paracetamol metabolite inhibit the reuptake of the endogenous cannabinoid/vanilloid anandamide by neurons, making it more available to reduce pain.

Paracetamol is available in a tablet, capsule, liquid suspension, suppository, intravenous, intramuscular and effervescent forms

Indication

Fever and Pain

Side effects

Can cause liver functions, pparacetamol poisoning and pprecautions for clients with a history of alcohol abuse, hepatitis or taking another paracetamol containing drugs.

ANGIOTENSIN CONVERTING ENZYME INHIBITORS

ANTIHYPERTENSIVE

Mechanism of action

Angiotensin-converting enzyme (ACE) inhibitors are a class of medications that are primarily used to treat hypertension (high blood pressure) and heart failure. They work by blocking the action of ACE, an enzyme that converts angiotensin I to angiotensin II, a powerful vasoconstrictor that raises blood pressure.

Therapeutic use

ACE inhibitors reduce the risk of heart attack, stroke, and other cardiovascular events in people with hypertension or heart failure. These medications are usually taken once or twice a day, with or without food, and are generally well-tolerated.

Side effects

The side effects include a persistent dry cough, dizziness, and low blood pressure.

ANGIOTENSIN RECEPTOR BLOCKERS

ANTIHYPERTENSIVE

Mechanism of action

Angiotensin receptor blockers (ARBs), also known as angiotensin II receptor antagonists, work by blocking the action of angiotensin II, a hormone that causes blood vessels to constrict, raising blood pressure. This causes blood vessels to relax, allowing blood to flow more easily and reducing blood pressure.

Therapeutic use

ARBs are often used as an alternative to angiotensin-converting enzyme (ACE) inhibitors, for people who cannot tolerate ACE inhibitors. People with hypertension and heart failure.

Side effects

Side effects include dizziness, low blood pressure, and an increased risk of hyperkalaemia (high potassium levels).

ANGIOTENSIN RECEPTOR BLOCKERS AND NEPRILYSIN INHIBITORS

ANTIHYPERTENSIVE

Mechanism of action

Angiotensin receptor blockers and neprilysin inhibitors (ARNIs) are a newer class of medication used to treat heart failure. They work by combining two types of medications: angiotensin receptor blockers (ARBs) and neprilysin inhibitors. nARBs block the action of angiotensin II, which constricts blood vessels and raises blood pressure. Neprilysin inhibitors work by inhibiting the enzyme neprilysin, which breaks down natural substances in the body that promote blood vessel dilation and lower blood pressure.

Therapeutic use

ARNIs can improve heart function and reduce