Multiple Choice Questions (MCQ) on Veterinary Pharmacology (Part-1)

ANSWERS & EXPLANATIONS

1.

b. (Water soluble)

Drug metabolism is the essential pharmacokinetics process, which render lipid soluble and non-polar compound to water soluble and polar compounds so that they are excreted by various process from the body.

Metabolism involves:

a. Phase 1: Functionalization reactions (converts the parent drugs to a more polar metabolite by introducing or unmasking a functional group (-OH, - NH2, -SH)

b.  Phase 2:  Conjugation reactions (Glucuronic acid, Sulfate, Glycine and other amino acids, Glutathione or Mercapturic acid, Acetylation, Methylation) 

2.

d. (Tolerance)

A more gradual decrease in response to drugs taking days or weeks to develop is called: Tolerance.

Drug resistance:  Ability of the disease- causing germs (Bacteria or virus) to continues multiplying despite the presence of drug that usually kills them.

Tachyphylaxis: Sudden decrease in response to drugs i.e. rapidly development of tolerance.

Drug desensitization: it is the process of temporary induction of tolerance to a sensitized drug by administering slow increments of the drug, starting from the small amount to a full therapeutics dose, used as a therapeutics strategy for patients with drug hypersensitivity when no comparable alternatives are available.

3.

b. (Preferentially COX2)

The anti – inflammatory effects of meloxicam is due to its ability to inhibits preferentially COX2.

Preferentially COX1 inhibitors: Ketoprofen,  Indomethacin,  Aspirin , Meclofenamate

Preferentially COX2 inhibitors: Diclofenac, Celecoxib, Meloxicam, Etoricoxib

Non-selective:  Ibuprofen, Sodium salicylate 

Note:

Lipooxygenase, play vital role in conversion of arachidonic acid into leucotrienes (mediator of inflammation). Example of Lipooxygenase inhibitors: Zileuton, Zyflo, Zyflo Filmtab,  Zidflo CR.

4.

c. (Half –life)

The time- lag for the drug to fall one- half of the original concentration in plasma is called Half- life.

Bioavailability: Bioavailability refers to the amount of active drug that reached into circulation.

Clearance: Removal of the drug from the plasma.

Elimination: Removal of the drug from the body. 

5.

a. (Cell wall synthesis)

Bactericidal antibiotics: 

Penicillin, Cephalosporins Are Very Bactericidal for Microorganism.

Penicillin, Cephalosporins, Aminoglycosides Vancomycin Flouroquinone Metronidazole. 

Bacteriostatic antibiotics: Chloramphenicol, clindamycin, erythromycin, sulfamethazole, Tetracycline, Trimethoprim.

Penicillin and Cephalosporins, Vancomycin: Inhibits cell wall synthesis.

Aminoglycosides: Inhibits protein synthesis 

Fluoroquinolone:  Inhibits DNA synthesis

Metronidazole: Fragmentation of DNA

Sulphonamide: inhibits folic acid synthesis, structural analogues of PABA ( para – amino benzoic acids)

Clindamycin: Inhibits protein synthesis by binding to 50’s’ ribosomal subunit.

Chloramphenicol: Inhibits protein synthesis by binding to 50 ‘s’ subunit.

Tetracycline: Inhibits protein synthesis by binding to 30 s ribosomal subunits. 

6.

b. (Fluroquinone)

Side effect of Antibiotics:

Flouroquinone - Arthropathy

Sulphonamide - hypersensitivity,  kernicterus, bone marrow depression, crystalluria, hemolytic aplastic anemia

Aminoglycosides : Nephrotoxicity and ototoxicity

Tetracycline: GIT toxicity, photosensitivity, liver damage, dentition and bone damage, Expired drugs (Fanconi)

7.

b. (Cytoplasm)
The receptors for steroidal hormones are found in Cytoplasm.
The receptors act on DNA/RNA are found in Nucleus.
The receptors act on glycoproteins - Cell wall.

8.

c. (Nitric oxides)
Previously identified endothelium derived relaxing factor is currently known as Nitric Oxides.

Nitric Oxides:

• Nitric oxides (NO)
• Reduces the oxidation of LDL cholesterol ( major component of plague)
• Dilates blood vessels
• Reduces platelets stickiness
• Reduces release of superoxide's radicals
• Least potent inhalant anaesthetic
• Has second gas effects.

9.

b. (Cobra)
Acetylcholinesterase enzymes is relatively rich in the venom of Cobra.
Russell’s viper venom contains 2 well known proteinase: a serine proteinase designated as ‘Russell’s viper venom factor V activator.’ A Metalloproteinase designated as ‘Russell’s viper venom coagulation factor X- activating enzyme.’
Common krait’s venom contains Beta- bungarotoxins, which are presynaptic neurotoxins with phospholipase A2 activity and considered to be the major cause of paralysis.
Pit viper venom is a highly complex mix of toxins, including metalloproteinases that cause local tissue destructions and thrombin like protein that causes a coagulopathy.

10.

c. (Ricin)
The toxalbumin present in the castor bean – Ricin.
The toxin Mimosin is present in large quantities in leaves, pods and seeds of tropical legumes of the genus Leucaena and plant Mimosa pudica.
Strychnine is the toxic alkaloid derived from the seeds of the tree Strychnos nux vomica.
Hyoscine (Scopolamine), alkaloid drug, obtained from the plant of family Solanaceae (nightshade, henbane and jimsonweed).

11.

a. (L- glutamate)
The excitatory amino acids neurotransmitter in the CNS is L- glutamate while inhibitory neurotransmitter in the CNS are GABA and Glycine.

12.

b. (Tamoxifen citrate)
A non- steroidal compound with anti- estrogenic effects is Tamoxifen Citrate.
Tamoxifen citrate is a drug used to treat certain types of breast cancer in women and men.
Finasteride (Antiandrogenic hormone) is to shrink an enlarged prostate glands by stopping testosterone turning into another hormone called dihydrotestosterone.
Diethyl stilbesterol: synthetic form of Estrogen used to prevent miscarriage, premature labor, and related complication of pregnancy.
Flutamide: Non-steroidal antiandrogen that competitively binds with androgen receptors throughout the body.

13.

c. (OH)
Most reactive Oxygen species: Superoxide> Hydroxyl> peroxyl> Alkoxyls> Hydroperoxyl
Most reactive Nitrogen species: Nitric oxide> Nitrogen dioxides

14.

a. (Salinomicin)
Ionophore with anticoccidial properties – Salinomycin
Nicarbazin : equimolar complex of 4,4- Dinitrocarbanilide and 2- Hydroxy-4,6- dimethyl pyrimidine with anticoccidial properties
Amprolium: Amprolium is thiamine analogs and block the thiamine transporter of Eimeria species (used as coccidiostat drug).

15.

d. All
Albendazole, Closantel and Netobimin are effective against all types of helminths parasites (Trematodes, Cestodes and Nematodes)
Drug of Choice for flatworm/ Trematodes: Triclabendazole (12mg/kg b.wt.)> Oxyclozanide (10-15 mg/kg b.wt)
Drug of Choice for tapeworm: Praziquantel (10-15mg/kg b.wt.)> Niclosamide ( 75-100mg/kg b.wt)
Drug of Choice for Roundworm: Piperazine (200mg/kg b.wt.) > Levamisole (7.5mg/ kg b.wt.)

16.

c. (Diminazine)
Drug acts as babesicidal and trypanocidal: Diminazine
Drug of Choice for theleria: Buparvaquone
Drug of choice for Anaplasma: Doxycycline

17.

a. (Potassium permagnate)
Example of oxidizing disinfectants: Halogen, chlorine, iodine, bromine, chlorine dioxide and peracetic acid and hydrogen peroxides.
Reducing disinfectants: Formaldehyde, Glutaraldehyde

18.

a. (Choline mimetic action)
Pyrantel pamoate has choline mimetic action, acts as a depolarizing neuromuscular blocking agent, thereby causing sudden contraction, followed by paralysis of the helminths.

19.

c. (3rd generation Cephalosporins)

Classification of Cephalosporins:

1st generation cephalosporins: Cefazolin, cefalothin, Cefaloridin, Cefadroxil, Cephalexin, cephradine
2nd generation cephalosporins: Cefoxitin, cefprozil, Cefotitan, Cefmetazole, Cefaclor, Cefuroxime
3rd generation cephalosporins: Cefexime, ceftazidime, cefotaxime, ceftizoxime, cefpodoxime, Ceftriazone, Cefoperazone, Ceftibuten, Cefdinir, Moxalactam
4th generation cephalosporins: Cefepime, Cefpirole
5th generation cephalosporins: Ceftibiprole, Ceftaroline

20.

a. (Monobactams)
Monobactams are the class of beta- lactam antibiotics with a broad spectrum of antibacterial activity and have a structure which render them highly resistant to beta- lactamases.

Classification of Penicillin

On the basis of sources, natural (Penicillin G and Penicillin V) and semisynthetic (Cloxacillin, Dicloxacillin, Methicillin, Nafcillin, Oxacillin)
On the basis of Route of administration, Oral (Penicillin V, Amoxicillin, Ampicillin, Oxacillin) and parental (Penicillin G, Methicillin, Nafcillin, Carbencillin, piperacillin)
On the basis of spectrum to activity, Narrow (Methicillin, Oxacillin, Nafcillin, Dicloxacillin); Broad (Amoxicillin and Ampicillin); Intermediate spectrum (Penicillin V and Penicillin G); Extended spectrum (Carbencillin and Piperacillin)
On the basis of resistance to Beta lactamases enzymes, Resistance to enzymes (Methicillin, nafcillin, Oxacillin, Dicloxacillin, Cloxacillin) and non- resistance (Penicillin G, Penicillin V, Amoxicillin, Ampicillin, Carbencillin)
On the basis of resistance to acids, Acid stable (Penicillin V, Amoxicillin, Ampicillin, Oxacillin, Dicloxacillin, Cloxacillin) and Acid Unstable (Penicillin G, Methicillin, Nafcillin, Carbencillin, piperacillin, ticarcillin)

21.

b. (Sulfafurazole)
Sulphonamide used in acute Urinary tract infections - Sulfafurazole

22.

b. (Inhibiting RNA synthesis)
Rifampicin acts by inhibiting RNA synthesis.
Rifampicin actually inhibits DNA dependent RNA polymerase enzymes, leads to inhibition of RNA synthesis.

23.

a. (Azathioprine)
Azathioprine is the immunosuppressive agent that acts through it’s effects as an antagonists of purine metabolism, resulting in the inhibition of DNA, RNA and protein synthesis.
Fluorouracil, part of chemotheroeutics drug ( anti metabolites), stops the cancer cells growth by stopping them making and repairing DNA.
Vincristine (Anti tumor Drug), inhibits the formation of microtubules formation of mitotic spindles, resulting in the arrest of dividing cells at the metaphase stage.
Methotrexate, Folate antagonist, results in the deficiency in the cellular pool of thymidylate and purines and thus in a decrease in nucleic acids synthesis.

24.

b. (Selenium poisoning)

• Alkali disease occurs in selenium poisoning.
• Garlic odor of GIT contents - Phosphorous poisoning
• Deep green color of Feces - Copper poisoning
• Hepatotoxicity and photosensitization - Lantana foliage toxicity
• Bright red unclotted venous blood - Cyanides poisoning
• Basophilic stippling is observed in - Lead poisoning
• Chocolate brown colored blood in PM - Nitrate poisoning

25.

a. (Brain and spinal cord)
Absorbed mercury is stored in body in Brain and Spinal Cord.

Note:

There is no antidote for mercury toxicity.
Arsenic mainly stored in keratinized part of body.
Antidote of Metal toxicity:
Arsenic BAL or Dimercaprol or sodium thiosulfate
Copper Ammonium molybdate + sodium sulfate
Lead Ca - disodium EDTA
Molybdenum Copper sulphate
Nitrate and nitrite 1% methylene blue

26.

a. (Leuiothionol)
Phenothiazine when wet is oxidised and metabolised to Leuiothionol.
Phenothiazines are used to treat serious mental and emotional disorders including schizophrenia and other psychotic disorders.

27.

a. (Abrin)
Toxic principle of Rosary peg is Abrin.
Ricin is found in Castor bean.

Note: Plant Toxicity along with their antidote:

• Cyanogenic plants: Sodium nitrite + sodium thiosulfate
• Oxalates : Lime water or dica- phosphates
• Nitrate/Nitrite: Methylene blue
• Abrus poisoning: Antiabrin serum
• Kaner: Atropine sulfate, Antihistamine
• Caster: Ricin antiserum
• Sweet clover: Vitamin K

28.

b. (Diffusion)
Diffusion is the most important means by which drugs enter the body and are distributed across cell boundaries. Drug (Unionized form) is absorbable form, passes through cell membrane while ionized form is excretable form.

Some facts related to Active Transport:

• Active transport utilizes carrier substances.
• It requires energy expenditure
• It is for drugs whose transportation is against concentration gradients.

29.

a. (When the drug antagonism is competitive)
The log dose - response curves of agonist given alone and given with antagonist, are parallel when the drug antagonism is competitive and below the agonist given alone curve when the drug antagonism is non- competitive.

30.

c. (Transduction)

Acquired drug resistance mechanism:

a. Transduction: Phage can transfer DNA from one bacterium to another
b. Transformation: When bacterial cells die, they frequently lyse, releasing their intracellular contents, including fragments of DNA to the environment. These fragments can be taken up and incorporated into the chromosome of a living bacterium to provide the recipient with new characteristics.
c. Conjugation: Bacteria transfers their resistance gene to another bacterium via conjugation tube.
d. Mutation: Due to mutation disease resistance developed in mutated gene.

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