Compare and Recall: Key Pharmacology Tables for NEET PG Success

Primary Pharmacokinetic parameters

Secondary Pharmacokinetic parameters

• Absorption
• Bioavailability (BA) of the drug- Amount of drug coming into the blood
• Distribution
• The volume of distribution (Vd)
• Metabolism, Excretion
• Clearance capacity (CI) – Power of the body to excrete drug

• Half-life (t1/2)
• Loading dose
• Maintenance dose

Phase 1 reaction 

Phase 2 reaction

Activity of the drug

Drugs convert into

• Active form
• Inactive form

• Converts into inactive form only
• Except: Morphine, Minoxidil
• Converted into an active form
• Enzymes transfer polar groups

Type of reaction

Oxidation

• CYP-450 enzyme

Reduction

• CYP-450 enzyme

Hydrolysis

• Hydrolase enzyme: Esters

Deamination

• Adenosine deaminase: Purines (Adenosine)

Dehydrogenation

• Alcohol dehydrogenase: Alcohols

Cyclization

• Proguanil

Decyclization

Glucuronide conjugation

• Uridine Di-phosphate glucuronyl transferase (UDPGT)

Acetylation (add Acetyl group)

• Acetyltransferase: SHIP drugs

Methylation

• Methyl transferase

Glycination

Sulfation

Glutathionylation

• Paracetamol

Most common

reaction

Most drugs undergo oxidation and

reduction

Most drugs undergo Glucuronide conjugation

Site of

reaction

Smooth Endoplasmic Reticulum (SER)

Also known as Microsomes

Microsomal reactions

Outside SER

• Non-microsomal reactions

Except: Glucuronide conjugation

• Microsomal reactions

Microsomal system 

Non-microsomal system

Location 

Inside SER 

Outside SER

Number of drugs metabolized

Most of the drugs

Few drugs

Activity of the system

Increased/ decreased by drugs

• Enzyme inducers
• Enzyme inhibitors

Not affected by drugs

Genetic polymorphisms

Seen

Seen

Agonist Physiological

Antagonist

Histamine- Bronchoconstriction

Adrenaline- Bronchodilation

Leukotrienes- Bronchoconstriction (LT receptor)

Salbutamol- Bronchodilation (β2 receptor)

PG-I2 - Antiplatelet action

Thromboxane- Platelet aggregation

PTH- Hypercalcemia

Calcitonin- Hypocalcemia

Insulin- Hypoglycemia

Glucagon- Hyperglycemia

β-blocker- Decreases heart rate

Glucagon- Increases heart rate

Do TDM 

Don't Do TDM

• Must do in case of narrow Therapeutic index drugs (low safety margin)
• Cannot monitor the toxic effects
  • Lithium
• Poisoning of drug
• Nephrotoxic drugs in renal disease
  • Aminoglycosides
• To check the compliance (timely intake of drugs)
  • Antiepileptics (Phenytoin) - If missed, can cause rebound seizures

• Wide safety margin
• Can easily monitor the toxic effects
  • Insulin
  • Warfarin
• Hit and run drugs
  • Irreversibly attached to organs
  • Not present in plasma
  • Ex: Aspirin
• Pro-drugs
  • Converted into another metabolite

Reuptake 

Degradation

• The action of Dopamine and norepinephrine is terminated by reuptake into the neurons
• Dopamine is reuptake by a transporter called DAT (Dopamine transporter)
• Norepinephrine is removed by a transporter called NET (norepinephrine transporter)
• Epinephrine is removed by the Liver with the help of ENT (extra neuronal transporter)

• Once the cathecolamines are reuptaken in to the neurons
• MAO enzyme and COMT enzyme present in the neurons and liver degrade these catecholamines

Neurogenic Diabetes Insipidus

Nephrogenic Diabetes Insipidus

• Lack of ADH secretion by hypothalamus
• Central diabetes insipidus
• DOC: Desmopressin
• Other drugs (Increases ADH secretion from brain)
  • Chlorpropamide (also used in diabetes mellitus)
  • Carbamazepine

• ADH secretion is present but ADH receptors are non responsive
• Desmopressin is not effective
• DOC: Thiazide diuretics
• Sometime Indomethacin (NSAID) is added
• Lithium causes Lithium induced nephrogenic diabetes insipidus
  • DOC: Amiloride

Phosphodiesterase 5 inhibitors

• It includes
  • Sildenafil
  • Tadalafil
  • Avanafil
  • Vardenafil
• ROA: Oral
• Side effects of sildenafil
  • Blue green color blindness
  • Hypotension, Headache

Alprostadil

• Prostaglandin E1
• ROA: Cavernosal injection

Phentolamine/Papaverine

• Vasodilator
• ROA: Cavernosal injection

Apomorphine

• ROA: Cavernosal injection

Topical drugs 

Oral drugs

• Permethrine (5%) lotion → DOC
  • Also used for head lice
  • Safe in pregnancy and can be given to children
• Lindane (Benzine hexachloride)
• Benzyl benzoate
• Crotamiton
  • The above drugs are not given during pregnancy or to children

Ivermectin

Bacteriostatic (MS COLT)

Bactericidal (BANG Q RIP)

Macrolides

Sulphonamides

Chloramphenicol

Oxazolidinone (Linezolid)

Lincosamides (Clindamycin)

Tetracycline

Beta lactams (Penicillins, Cephalosporins,

Carbepenems, Monobactams)

Aminoglycosides

Nitroimidazole (Metronidazole)

Glycopeptides (Vancomycin)

Quinolones

Rifampicin

Polymyxin (colistin)

Omalizumab

• Blocks IgE
• Location- Surface of mast cells
• Uses- Chronic asthma, urticaria, nasal polyps
• Route: S/C injection once/month

Mepolizumab

• Route: S/C injection
• Blocks IL-5
• Treat chronic asthma, Churg Strauss syndrome

Reslizumab

• Route:IV injection
• Blocks IL-5
• Treat chronic asthma, Churg Strauss syndrome

Benralizumab 

• Blocks IL-5 receptors

Dupilumab

• Blocks IL-4 receptors

Tezepelumab

• Newer drug
• Blocks Thymic stromal lymphopoietin (TSL)

Irreversible blockers 

Reversible blockers

• Ticlopidine
• Clopidogrel
• Prasugrel
• All are prodrugs (Inactive drugs)

• Ticagrelor
• Cangrelor – IV drug (used during Percutaneous transluminal coronary angioplasty (PTCA)
• Active drugs

Small Molecules

Monoclonal Antibodies

• Molecular weight: <900 Dalton
• Enters inside the cells to inhibit
  • Protein kinase receptors
  • Signaling molecule
  • DNA directly
• Given orally

• Large molecules (peptides)
• Act only from the surface
• These are injectables

Atracurium 

Cis Atracurium

Mixture of >10 isomers

Only 1 isomer

Metabolised by Hofmann elimination and plasma esterase

Metabolised by Hofmann elimination

(100%)

Histamine release leading to allergy

No histamine release

Laudanosine is a toxic form that accumulates in renal failure leading to a high risk of seizures

Not seen

Mechanism 

Drug

No functional impairment or asymptomatic

Seligiline or rasagiline (Only neuroprotective drug)

Functional impairment

Levodopa (DOC and most effective) >>> Mild PD

(Ropinirole or pramipexole)

Inhibit peripheral degradation of levodopa

Carbidopa, Benserazide

Levodopa-induced dyskinesia

Amantadine, Levitiracetam

Prolong ON phase

Entacapone → MAO-B inhibitors → Tolcapone

Reduce OFF phase

Injection Apomorphine

Vomiting

Domperidone

Psychosis

Clozapine, quetiapine, pimavanserin

Resting tremors (levodopa is not effective)

Anticholinergics like Benzhexol are used.