D. PHARMACY 2ND YEAR PHARMACOLOGY IMPORTANT LONG QUESTIONS WITH ANSWERS PART 3

 

PHARMACOLOGY IMPORTANT LONG QUESTIONS (15 MARKS)

(PART 3: QUESTION NO. 15-21)

PREPARED BY MR. ABHIJIT DAS

 

1.    What do you mean by parenteral route? What are advantages of parenteral routes over oral route? Classify parenteral route.

2.    Define absorption of drugs. Give a note on different processes of absorption of drugs and factors affecting the absorption process.

3.    Define biotransformation of a drug. Describe various processes of drug metabolism.

4.    Explain the various factors affecting the dose and action of drugs.

5.    Define cholinergic drugs. Classify it with suitable suitable examples. Give a note on pharmacological action of acetylcholine.

6.    What do you mean by sympathomimetics and parasympathomimetics? Classify anti-cholinergic drugs. Discuss pharmacological action of atropine on eye, CVS, glands and smooth muscles.

7.    Define adrenergic drugs & classify them. Describe about pharmacological action, adverse effect and use of adrenaline.

8.    Write down the definition, classification, mechanism of action, pharmacological action and use of local anaesthetics.

9.    Explain general anaesthetics. Briefly describe the different stages of general anaesthesia. Write a note on barbiturates.

10.                       What are NSAIDS? Classify them. Write the mechanism of action, pharmacological action and uses of aspirin.

11.                       what is the difference between narcotic and non-narcotic analgesics? Classify opiod  analgesics. Give a note on pharmacological actions, ADME, side effects and therapeutic effects of morphine.

12.                       Define epilepsy. Describe shortly different types of epilepsy. Classify anti epileptic drugs. Write the mechanism of action and adverse effects of phenytoin.

13.                       What is sedative? Classify the drugs used as sedative-hypnotics. Give an account of pharmacological action, ADME, adverse reactions and therapeutic uses of barbiturates.

14.                       Define diuretics. Classify it. Write down the pharmacological action, adverse effect and use of furosemide.

15.                       What do you mean by cardiac glycosides? Write the mechanism of action, pharmacological action, adverse effects and uses of digoxin.

16.                       Enumerate the drugs used for the treatment of peptic ulcer and describe pharmacological action, toxicities of H2 blockers.

17.                       What is purgative? Classify it with example. Give a note on irritant purgatives.

18.                       Define chemotherapeutic agents and antibiotics. Write the mechanism of action of penicillins and a note on semi-synthetic penicillins. Or Classify penicillins and describe their method of action, toxicity and therapeutic uses.

19.                       What is tuberculosis? Classify anti tubercular drugs with examples. Give a note on firstline anti tubercular drugs.

20.                       What is amoebiasis? Classify antiamoebic drugs. Discuss about the mechanism of action, pharmacokinetics, side effects and uses of metronidazole.

21.                       What is cancer? Classify anti cancer drugs. Discuss shortly the mechanism of action of anti metabolites and alkylating agents.

 

15.       WHAT DO YOU MEAN BY CARDIAC GLYCOSIDES? WRITE THE MECHANISM OF ACTION, PHARMACOLOGICAL ACTION, ADVERSE EFFECTS AND USES OF DIGOXIN.

ANS:

CARDIAC GLYCOSIDES

Cardiac glycosides are medicines that increase the cardiac output and rate of contraction of heart.

They are used for treating heart failure and certain irregular heart beats.

Cardiac glycosides are found in several plants, including the leaves of the digitalis plant. This plant is the original source of this medicine.

DIGOXIN

Digoxin is one of the oldest medications used in the field of cardiology.

It is taken through oral route or by injection into vein.

MECHANISM OF ACTION OF DIGOXIN

Digoxin is a potent inhibitor of Na+/K+-ATPase.

This inhibition promotes sodium-calcium exchange, which increases the intracellular calcium concentration, resulting in an increase in the force of myocardial contraction.

Calcium particles bind to cell that helps the cell to contract, which makes the heart to pump blood.



PHARMACOLOGICAL ACTIONS

HEART

Digoxin increases myocardial contractility in the failing heart. It also increases cardiac output.

Digoxin helps to increase the heart rate.

BLOOD VESSELS

Digoxin has mild direct vasoconstriction action. Systolic blood pressure may increase and diastolic blood pressure may fall in CHF patients.

KIDNEY

Diuresis is seen in CHF patients. The retained salt and water is gradually excreted.

No diuresis occurs in normal individuals due to other causes.

CNS

Digoxin has little effect on CNS in therapeutic doses.

Higher doses causes nausea and vomiting.

Still higher doses produce mental confusion, disorientation and visual disturbances.

ADVERSE EFFECTS OF DIGOXIN

The adverse effects are often grouped as cardiac and extra cardiac.

CARDIAC

Ø Delayed AV conduction

Ø Ventricular tachycardia

Ø Ventricular fibrillation

EXTRA CARDIAC

Ø Nausea & vomiting

Ø Anorexia (fear of being overweight)

Ø Head ache

Ø Blurring of vision

Ø Mental confusion

THERAPEUTIC USES

1.    Digoxin is used to treat heart failure.

2.    Digoxin is also used to treat cardiac arrhythmias.

 


16.       ENUMERATE THE DRUGS USED FOR THE TREATMENT OF PEPTIC ULCER AND DESCRIBE PHARMACOLOGICAL ACTION, TOXICITIES OF H2 BLOCKERS.

ANS:

DRUGS USED FOR THE TREATMENT OF PEPTIC ULCER

1.    REDUCTION OF GASTRIC ACID SECRETION

a.     H2 BLOCKERS: Cimetidine, Ranitidine, Famotidine, Roxatidine

b.    PROTON PUMP INHIBITORS: Omeprazole, Lansoprazole, Pantoprazole, Rabeprazole, Esomeprazole

c.     ANTICHOLINERGICS: Pirenzepine, Propantheline, Oxyphenonium

d.    PROSTAGLANDIN ANALOGUE: Misoprostol

2.     NEUTRALIZATION OF GASTRIC ACIDS (ANTACIDS)

a.     SYSTEMIC: Sodium bicarbonate, Sodium citrate

b.    NONSYSTEMIC: Magnesium hydroxide, Magnesium trisilicate, Aluminium hydroxide gel, Magaldrate, Calcium carbonate

3.    ULCER PROTECTIVES: Sucralfate, Colloidal bismuth subcitrate (CBS)

4.    ANTI H.PYLORY DRUGS: Amoxicillin, Clarithromycin, Metronidazole, Tinidazole, Tetracyclin

H2 BLOCKERS

These drugs are the first class of highly effective drugs for peptic ulcer.

These drugs inhibit the action of histamine on H2 receptors and thereby reduce gastric secretion.

They can cause 90% reduction in gastric secretion by a single dose.

Four H2 blockers cimetidine, ranitidine, famotidine and roxatidine are available in india.

MECHANISM OF ACTION

All four drugs have similar mechanism of action..

Combination of histamine with H2 receptors present on the surface of gastric parietal cell increases HCl secretion.

But when H2 receptor blockers bind with the H2 receptor and block the binding of histamine with H2 receptors, resulting in inhibition of HCl secretion.



PHARMACOLOGICAL ACTIONS

H2 BLOCKADE: H2 blockers block histamine induced gastric secretion.

BLOOD VESSELS: They cause fall in blood pressure

LUNGS: They cause bronchial relaxation. So H2 blockers are used in histamine induced bronchospasm.

ADVERSE EFFECTS

1.    Diarrhoea

2.    Muscle pain

3.    Dry mouth

4.    Rashes

5.    Dizziness

6.    Headache

THERAPEUTIC USES

1.    They are used to treat duodenal ulcer and gastric ulcer

2.    They are used to treat Zolinger-Ellison Syndrome ( a rare digestive disorder that results in too much gastric secretion).

3.    They are also used to treat GERD (gastro esophageal reflux disease).

 

 

17.       WHAT IS PURGATIVE? CLASSIFY IT WITH EXAMPLE. GIVE A NOTE ON IRRITANT PURGATIVES.

ANS:

PURGATIVES

Purgatives are drugs that promotes defecation. They are also called laxatives or cathartics. Laxatives are milder evacuants while cathartics are more powerful evacuants.

CLASSIFICATION OF PURGATIVES

1.    BULK FORMING AGENTS

Dietary fibre: Bran, Psyllium (Plantago), Ispaghula, Methylcellulose

2.    STOOL SOFTNER

Docusates (DOSS), Liquid Paraffin

3.    OSMOTIC PURGATIVES

Magnesium Sulfate, Magnesium Hydroxide, Sodium Sulfate, Sodium Phosphate, Lactulose

4.    STIMULANT PURGATIVES/IRRITANT PURGATIVES

A.  DIPHENYLMETHANES: Phenolphthalein, Bisacodyl, Sodium Picosulfate

B.   ANTHRAQUINONES (EMODINS): Senna, Cascara Sagrada

C.   5-HT4 AGONIST: Tegaserod

D.  FIXED OIL: Castor Oil

STIMULANT PURGATIVES/IRRITANT PURGATIVES

These are powerful purgatives. They produce peristalsis in the small or large intestine which helps in purgation.

They may cause abdominal cramps.

Larger doses of stimulant purgatives can cause excess purgation resulting in fluid and electrolyte inbalance.

1.   BISACODYL

MECHANISM OF ACTION

Bisacodyl is converted to active metabolite in the intestines.It irritates colonic mucosa to increase fluid secretion as well as stimulates enteric neurons to promote peristaltic movements.

ADVERSE AFFECTS

Ø Nausea

Ø Diarrhea

Ø Stomach pain or cramps

2.   SODIUM PICOSULFATE

MECHANISM OF ACTION

It is hydrolysed by colonic bacteria to the active form, which then acts locally to irritate the mucosa and activate the enteric neurons, resulting in peristalsis.

ADVERSE EFFECTS

Ø Nausea

Ø Diarrhea

Ø Headache

Ø Stomach pain

3.    SENNA

MECHANISM OF ACTION

They are activated into their active form in the intestines and stimulate the enteric neurons in the colon, resulting in peristalsis.

ADVERSE EFFECTS

Ø Nausea

Ø Diarrhea

Ø Stomach pain

Ø Excessive bowel activity

4.   CASTOR OIL

MECHANISM OF ACTION

Castor oil is hydrolysed in the upper small intestine to ricinoleic acid, a local irritant that increases intestinal motility.

ADVERSE EFFECTS

Ø Nausea

Ø Diarrhea

Ø Stomach pain

Ø Electrolyte disturbance

 

18.       DEFINE CHEMOTHERAPEUTIC AGENTS AND ANTIBIOTICS. WRITE THE MECHANISM OF ACTION OF PENICILLINS AND A NOTE ON SEMI-SYNTHETIC PENICILLINS. OR CLASSIFY PENICILLINS AND DESCRIBE THEIR METHOD OF ACTION, TOXICITY AND THERAPEUTIC USES.

ANS:

Penicillins are a type of antibiotic derived from penicillium fungi (Penicillium notatum & Penicillium chrysogenum).

Most penicillins in clinical use are chemically synthesized from naturally produced penicillins.

These penicillin antibiotics have a beta-lactam ring. The beta-lactam antibiotics act by inhibiting the cell wall synthesis in the bacteria.

 

CHEMOTHERAPEUTIC AGENTS

These are synthetic compounds which suppress the growth or kill microorganisms. These drugs also inhibit the growth of malignant cells (cancer cells).

ANTIBIOTICS

These are substances produced by microorganisms which suppress the growth or kill bacteria.

 

CLASSIFICATION

A.  NATURAL: Penicillin G

B.   SEMISYNTHETIC:

1.    ACID RESISTANT PENICILLINS: Penoxymethyl Penicillin (Penicillin V)

2.    PENICILLINASE RESISTANT PENICILLINS: Methicillin, Cloxacillin

3.    EXTENDED SPECTRUM PENICILLINS

a.     Aminopenicillins: Ampicillin, Bacampicillin, Amoxicillin

b.    Carboxypenicillins: Carbenicillin, Ticarcillin

c.     Ureidopenicillins: Piperacillin, Mezlocillin

4.    BETA-LACTAMASE INHIBITORS: Clavulanic acid, Sulbsctsm, Tazobactam

MECHANISM OF ACTION

The beta-lactam antibiotics act by inhibiting the cell wall synthesis in the bacteria.

The cell wall of the bacteria protects it from lysis. Peptidoglycan, a complex polymer, is an important component of the cell wall.

Peptidoglycan consists of glycan chains which are cross-linked by peptide chains.

The synthesis of this peptidoglycan requires enzymes called transpeptidases.

Beta-lactam antibiotics inhibit these transpeptidases enzyme and thus inhibit the synthesis of the peptidoglycan, resulting in the formation of cell wall deficient bacteria. So bacteria undergo lysis.

That’s why penicillins are bactericidal.

PENICILLIN G

Penicillin G is a narrow spectrum antibiotic.

ADVERSE EFFECTS

1.    Hypersensitivity: skin rashes, urticarial, fever, bronchospasm and rarely anaphylaxis.

2.    Local pain at the site of injection, thrombophlebitis on IV injection.

3.    Large doses of penicillin G may produce confusion, muscle twitching, convulsion and coma.

USES

Penicillin G is the antibiotic of choice for several infections unless the patient is allergic to it.

1.    Orodental infection

2.    Pneumococcal infection

3.    Streptococcal infection

4.    Meningococcal infection

5.    Staphylococcal infection

6.    Diptheria

 

SEMISYNTHETIC PENICILLINS

Semisynthetic penicillins are produced by chemically combining specific side chains in place of benzyl side chain of penicillin G.

The aim of producing semisynthetic penicillins has been to overcome disadvantages of penicillin G such as:

1.    Poor oral efficacy

2.    Susceptibility to penicillinase

3.    Narrow spectrum of activity etc. 

1.  ACID RESISTANT PENICILLINS

It differs from penicillin G because it is acid stable.

PHENOXYMETHYL PENICILLIN (PENICILLIN V)

It is administered orally.

It should not be preferred for more serious infections and is occasionally used for

·       Streptococcal pharyngitis

·       Sinusitis

·       Otitis media (ear infection)

·       Less serious pneumococcal infections

·       Trench mouth etc (gum infection)

2.  PENICILLINASE-RESISTANT PENICILLINS

These drugs have side chains that protect the beta-lactam ring from attack by penicillinase.

They are only used in infections caused by penicillinase producing staphylococci.

 

METHICILLIN

Methicillin is highly penicillinase resistant but not acid resistant.

Methicillin can be destroyed by gastric juice, hence given parenterally.

CLOXACILLIN

It is highly penicillinase as well as acid resistant.

It is given orally.

It is more active than methicillin against penicillinase producing bacteria.

3.  EXTENDED SPECTRUM PENICILLINS

These semisynthetic penicillins are active against a wide variety of bacteria.

AMPICILLIN

It is active against all organisms sensitive to penicillin G.

But due to wide spread use, many bacteria have developed resistance against amphicillin.

Ampicillin is not degraded by gastric acid. So oral route is adequate.

ADVERSE EFFECTS

1.    Diarrhea

2.    Intestinal irritation

3.    Hypersensitivity reaction

USES

1.    Urinary tract infections

2.    Respiratory tract infection

3.    Meningitis

4.    Gonorrhea

5.    Endocarditis

CARBENICILLIN

Carbenicillin is neither penicillinase-resistant nor acid-resiatant.

It is inactive orally and is excreted rapidly in urine.

ADVERSE EFFECT: Bleeding

USE: It is used to treat infections caused by pseudomonas (UTI, Septicaemia).

4.  BETA-LACTAMASE INHIBITORS

Beta-lactamase are a family of enzymes produced by many bacteria that inactivate beta-lactam antibiotics by opening the beta-lactam ring.

CLAVULANIC ACID

It inhibits a wide variety of beta-lactamases produced by many bacteria.

It is administered orally.

USE: It is used against beta-lactamase producing bacteria (E.coli, Salmonella, Shigella etc).

 

19.       WHAT IS TUBERCULOSIS? CLASSIFY ANTI TUBERCULAR DRUGS WITH EXAMPLES. GIVE A NOTE ON FIRSTLINE ANTI TUBERCULAR DRUGS.

ANS:

TUBERCULOSIS

Tuberculosis is a serious infectious bacterial disease, caused by mycobacterium tuberculosis, which mainly affects the lungs.

TB spreads from person to person through air.

When a person develops active TB disease, symptoms (such as cough, fever, night sweats or weight loss) may be mild for many months.

CLASSIFICATION OF ANTITUBERCULAR

DRUGS

FIRST LINE DRUGS

1.    Isoniazid

2.    Rifampin

3.    Pyrazinamide

4.    Ethambutol

5.    Streptomycin

SECOND LINE DRUGS

1.    Thiacetazone

2.    Paraaminosalicylic acid

3.    Ethionamide

4.    Cycloserine

5.    Kanamycin

6.    Amikacin

7.    Capreomycin

FIRSTLINE DRUGS: These drugs have high anti tubercular efficacy as well as low toxicity.

SECOND LINE DRUGS: These drugs have low efficacy and high toxicity.

 

FIRST LINE ANTI TUBERCULAR DRUGS

ISONIAZIDE (ISONICOTINIC ACID HYDRAZIDE)

Isoniazide is an essential component of all anti tubercular resimens. It is primarily tuberculocidal.

It is one of the cheapest anti tubercular drugs.

MECHANISM OF ACTION

Isoniazid inhibits the synthesis of mycolic acids which are unique components of bacterial cell wall.

ADVERSE EFFECTS

1.    Peripheral neuritis

2.    Mental disturbances

3.    Hepatitis

4.    Arthralgia (joint pain)

RIFAMPICIN

It is a tuberculocidal as well.

MECHANISM OF ACTION

Rifampicin inhibits DNA dependent RNA synthesis.

ADVERSE EFFECTS

1.    Hepatitis

2.    Breathlessness

3.    Haemolysis

4.    Rashes, redness and watering of eyes.

ETHAMBUTOL

Ethambutol is tuberculostatic.

MECHANISM OF ACTION

It inhibits mycolic acid incorporation in mycobacterial cell wall. So it works by inhibiting cell wall synthesis.

ADVERSE EFFECTS

1.    Rashes

2.    Fever

3.    Nausea

STREPTOMYCIN

It was the first clinically useful antitubercular drug.

It is tuberculocidal, but less effective than isoniazid or rifampin.

MECHANISM OF ACTION

Streptomycin blocks the ability of ribosomes to make proteins.

ADVERSE EFFECTS

1.    Stomach upset

2.    Lack of appetite

3.    Vertigo

4.    Chest pain

 

20.       WHAT IS AMOEBIASIS? CLASSIFY ANTIAMOEBIC DRUGS. DISCUSS ABOUT THE MECHANISM OF ACTION, PHARMACOKINETICS, SIDE EFFECTS AND USES OF METRONIDAZOLE.

ANS:

AMOEBIASIS

Amoebiasis is a parasitic infection of the intestines caused by the amoeba Entamoeba histolytica.

The symptoms of amoebiasis include loose stool, abdominal cramping, stomach pain etc. However, some people with amoebiasis won’t experience any symptom.

E. histolytica is a protozoan than enters the human body through water or food contaminated with stool.

The infection can also spread through the bloodstream to the liver.

CLASSIFICATION OF ANTIAMOEBIC DRUGS

1.    TISSUE AMOEBICIDES

a.     FOR BOTH INTESTINAL AND EXTRAINTESTINAL AMOEBIASIS:

NITROIMIDAZOLES: Metronidazole, Tinidazole, Secnidazole, Ornidazole, satranidazole

ALKALOIDS: Emetine, Dehydroemetine

b.    FOR EXTRAINTESTINAL AMOEBIASIS: Chloroquine

2.    LUMINAL AMOEBICIDES

a.     AMIDE: Diloxanide furoate, Nitazoxanide

b.    8-HYDROXYQUINOLINES: Quiniodochlor, Diiodohydroxyquin

c.     ANTIBIOTICS: Tetracyclines

METRONIDAZOLE

Metronidazole is one of the popular drugs for protozoal infections (E. histolytica).

MECHANISM OF ACTION



Metronidazole is selectively toxic to anaerobic microorganisms (E. histolytica is an anaerobic microorganism). E. histolytica reduces the nitro group of metronidazole by nitroreductase and convert it to a cytotoxic derivative which binds to DNA and inhibits protein synthesis.

PHARMACOKINETICS (ADME)

ABSORPTION: Metronidazole is well absorbed from the small intestines.

DISTRIBUTION: It is widely distributed in the body.

METABOLISM: It is metabolized in the liver by oxidation and glucuronide conjugation.

EXCRETION: Metronidazole is excreted in urine.

ADVERSE EFFECTS

1.    Anorexia (fear of being overweight)

2.    Metallic taste

3.    Abdominal cramps

4.    Dryness of mouth

5.    Rashes

6.    Seizures at high doses

THERAPEUTIC USES

1.    Metronidazole is used to treat amoebiasis.

2.    It is used to treat giardiasis (an intestinal infection caused by a giardia parasite).

3.    It is used to treat peptic ulcer.

4.    It is also used to treat trench mouth (a severe gum infection).

5.    It is also used to treat anaerobic bacterial infections.

  

21.       WHAT IS CANCER? CLASSIFY ANTI CANCER DRUGS. DISCUSS SHORTLY THE MECHANISM OF ACTION OF ANTI METABOLITES AND ALKYLATING AGENTS.

ANS:

CANCER

Cancer is a large group of diseases that can start in almost any organ or tissue of the body when abnormal cells grow uncontrollably.

One defining feature of cancer is the rapid creation of abnormal cells that grow beyond their usual boundaries, and which can then invade adjoining parts of the body and spread to other organs.

Cancer is the second leading cause of death globally (9.6 million deaths in 2018).

Other terms used for cancer are malignant tumours and neoplasm.

CLASSIFICATION OF ANTICANCER DRUGS

1.    ALKYLATING AGENTS

Nitrogen mustards: Mechlorethamine (Mustine HCL), Cyclophosphamide, Ifosfamide, Chlorambucil, Melphalan

Ethylenimine: Thio-Tepa

Alkyl sulfonate: Busulfan

Nitrosoureas: Carmustine, Lomustine

Triazine: Dacarbazine

2.    ANTIMETABOLITES

Folate antagonist: Methotrexate (Mtx)

Purine antagonist: 6-Mercaptopurine, 6-Thioguanine, Azathioprine, Fludarabine.

Pyrimidine antagonist: 5-Fluorouracil, Cytarabine

3.    VINCA ALKALOIDS: Vincristine, Vinblastine

4.    TAXANES: Paclitaxel, Docetaxel

5.    EPIPODOPHYLLOTOXIN: Etoposide

6.    CAMPTOTHECIN ANALOGUES: Topotecan, Irinotecan

7.    ANTIBIOTICS: Actinomycin D (Dactinomycin), Doxorubicin, Daunorubicin, Mitoxantrone, Bleomycins, Mitomycin C

8.    MISCELLANEOUS: Hydroxyurea, Procarbazine, L-Asparaginase, Cisplastin, Carboplatin, Imatinib

ANTIMETABOLITES

These drugs generally inhibit purine or pyrimidine synthesis in the cancer cells.

So no nucleotide is synthesized and no DNA or RNA is formed.

METHOTREXATE (MTX)

Methotrexate is the most important antimetabolite anticancer drug. Methotrexate inhibits folic acid synthesis.

MECHANISM OF ACTION

Mtx binds to dihydrofolate reductase (DHFR) and prevents the formation of tetrahydrofolate.

This tetrahydrofolate is essential in several reactions in DNA synthesis.

The deficiency results in inhibition of DNA synthesis.



ADVERSE EFFECTS

1.    Gastritis, gastric erosion

2.    Thrombocytopenia

3.    Hair loss

4.    Meningitis

6-MERCAPTOPURINE (6-MP)

It is structurally related to purine.

MECHANISM OF ACTION

6-MP enters the cancer cell and becomes converted to 6-mercaptopurine ribose phosphate (6-MPRP).

This 6-MPRP inhibits the synthesis of purine hence nucleic acid synthesis stops (DNA/RNA synthesis stops). So death of cancer cell occurs.

ADVERSE EFFECTS

1.    Joint pain

2.    Bone marrow suppression

3.    Liver inflammation

4.    Nausea, vomiting

 

ALKYLATING AGENTS

These drugs cause attachment of an alkyl group to the DNA strand of cancer cells and hence damaging the DNA strand.

MECHLORETHAMINE

MECHANISM OF ACTION

It alkylates the DNA strand leading to damage of the DNA strand.

ADVERSE EFFECTS

1.    Severe vomiting

2.    Bone marrow suppression

3.    Immune-suppression

 

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