INTRO TO PHARMACOLOGY FOR 4 SEM BPHARM

1. INTRODUCTION TO
PHARMACOLOGY,
PHARMACODYNAMICS &
PHARMACOKINETICS
1

2. INTRODUCTION
• Definition, historical landmarks and scope of
pharmacology.
• nature and source of drugs.
• essential drugs concept and routes of drug
administration.
• Agonists, antagonists( competitive and
noncompetitive).
• Spare receptors.
• Addiction, tolerance, dependence.

3. DEFINITION
• Pharmacology is the science of drugs (Greek:
Pharmakon—drug; logos—discourse in.
• In a broad sense, it deals with interaction of
exogenously administered chemical molecules with
living systems, or any single chemical substance which
can produce a biological response is a ‘drug’.
• It encompasses all aspects of knowledge about drugs,
but most importantly those that are relevant to
effective and safe use for medicinal purposes.

4. DIVISION OF PHARMACOLOGY
• Divisions of pharmacology are pharmacodynamics
and pharmacokinetics.
• Pharmacodynamics (Greek: dynamis—power) —
What the drug does to the body. This includes
physiological and biochemical effects of drugs and
their mechanism of action at organ
system/subcellular/macromolecular levels.
• Eg- Adrenaline → interaction with adrenoceptors →
G- protein mediated stimulation of cell membrane
bound adenylyl cyclase → increased intracellular
cyclic 3´,5´AMP → cardiac stimulation, hepatic
glycogenolysis and hyperglycemia, etc

5. • Pharmacokinetics Kinesis—movement)— -What the body does
to the drug. This refers to movement of the drug in and
alteration of the drug by the body; includes absorption,
distribution, binding/localization/storage, biotransformation
and excretion of the drug.
• e.g. paracetamol is rapidly and almost completely absorbed
orally attaining peak blood levels at 0–60 min; 25% bound to
plasma proteins, widely and almost uniformly distributed in the
body (volume of distribution ~ 1L/kg); extensively metabolized
in the liver, primarily by glucuronide and sulfate conjugation
into inactive metabolites which are excreted in urine; has a
plasma half life (t½) of 2–3 hours and a clearance value o f 5
ml/kg/min.

6. HISTORITICAL LANDMARKS
• For thousands of years most drugs were crude natural products of unknown
composition and limited efficacy.
• Pharmacology as an experimental science was ushered by Rudolf Buchheim
who founded the first institute of pharmacology in 1847 in Germany.
• In the later part of the 19th century, Oswald Schmiedeberg, regarded as the
‘father of pharmacology’, together with his many disciples like J Langley,T
Frazer, P Ehrlich,AJ Clark, JJ Abel propounded some of the fundamental
concepts in pharmacology.
• the era of antimicrobial chemotherapy began with the discovery by Paul
Ehrlich in 1909 of arsenical compounds for treating syphilis.

7. SCOPE
• The study of how medicines and other chemicals
interact with biological systems to create therapeutic
effects is the broad, diverse discipline of
pharmacology. Its reach encompasses several
domains, such as:
• Clinical pharmacologists investigate how
pharmaceuticals affect people, including possible
benefits and drawbacks, interactions with other
medications, and diversity in patient responses. They
are essential in the planning and interpretation of
clinical trials as well.

8. • Pharmacokinetics and pharmacodynamics: This area of
study examines how medications enter the body, travel
across it, metabolize, and leave it, as well as how they
influence the body (pharmacodynamics). recognizing these
mechanisms is essential for maximizing medication dosage
and effectiveness while reducing side effects.
• Drug Development and Discovery: Pharmacologists work
in the fields of drug discovery and development, creating,
synthesising, and testing new medications for a range of
illnesses. This entails comprehending the molecular causes
of illnesses and creating medications that can target
certain pathways.

9. • Neuropharmacology is a subfield of pharmacology
that studies how medications affect the nervous
system. It also treats neurological and psychological
disorders such epilepsy, depression, anxiety, and
Alzheimer's disease.
Cardiovascular Pharmacology: The study of
pharmaceuticals that impact the cardiovascular
system, such as those prescribed to treat arrhythmias,
hypertension, heart failure, and other cardiovascular
disorders, is done by pharmacists.

10. DRUG
• A drug is a material that, when ingested by the body, alters its
physiological or psychological conditions. Drugs can be
categorized according to a number of factors, including their legal
status, physiological effects, and chemical makeup. These can
include recreational drugs taken for non-medical purposes as well
as prescription pharmaceuticals written by medical practitioners
for therapeutic purposes. Drugs can affect the body in a variety of
ways, changing mood, perception, and consciousness in addition
to relieving pain and managing problems.

11. • Drug comes from the term "drogue," which refers to a
dry herb in French. A drug is any substance that is
used to diagnose, prevent, treat, or cure a disease in
humans or animals.
• A drug is defined as any substance used for the
purpose of diagnosis, prevention, relief or cure of a
disease in man or animals.

12. • "Any substance or product that is used or intended to
be used to modify or explore physiological systems or
pathological states for the benefit of the recipient" is
classified as a drug by the World Health Organization.
• of Substances The different drug suppliers are:
Minerals: such as aluminum trisilicate, magnesium
sulfate, liquid paraffin, and kaolin.
• Animal: such as antitoxic sera, heparin, insulin, and
gonadotropins.
• Plant: such as digoxin, morphine, atropine, reserpine,
and quinine. Plants are formed from the combination
of many chemical elements.

13. • Microorganisms: Isolated from soil, bacteria and fungi
are significant sources of antibacterial drugs like
penicillin.
• Synthetic medications include ACE inhibitors,
hypnotics, non-steroidal anti-inflammatory medicines,
and anticancer medications. Nowadays, synthetic
pharmaceuticals make up the majority of drugs used
in therapy.
• Hepatitis B vaccine and insulin are two examples of
genetic engineering (DNA recombinant technology).

14. SOURCE OF DRUGS
• Biologicals: In the last decade many biological agents have
also become available for therapeutic purposes. This is a
heterogeneous group and includes complex protein
molecules that interact with cytokines or cell surface
markers e.g. growth factors, monoclonal antibodies,
cytokines.
• Gene based therapy: The developments in biotechnology,
including recombinant DNAtechnology, have made it
possible to synthesize short nucleotide sequences (genes).

15. ESSENTIAL DRUG CONCEPT
• In 1977, the World Health Organization published its
first Model List of Essential Drugs, which included
dosage forms and strengths. These lists might be
used after appropriate changes based on local needs.
• India created its National List of Essential Medicines in
2011 after revising it in 1996 and renaming it the
National Essential Drugs List.

16. • This comprises 348 medications that are estimated to be appropriate
to address the nation's general population's top healthcare needs.
• Medications that meet a population's top healthcare demands are
considered essential. Their effectiveness, safety, and affordability
make them indispensable. These medications have been chosen on
the basis of comparative cost-effectiveness, safety, evidence of
efficacy, and frequency of the disease.

17. ROUTE OF DRUG ADMINISTRATION
• Routes can be broadly divided into those for :
o Local action and
oSystemic action
• LOCAL ROUTES: These routes can only be used for
localized lesions at accessible sites and for drugs
whose systemic absorption from these sit es is
minimal or absent.

18. • The local routes are:
oTopical
oDeeper tissues
o Arterial supply
• TOPICAL: This is the process of applying a medicine
externally to the skin in order to achieve localized
effect.
• Drugs can be effectively administered as lotions,
ointments, creams, powders, rinses, paints, drops,
sprays, lozenges, suppositories, or pesseries to the
localized lesions on skin, oropharyngeal/nasal
mucosa, eyes, ear canals, anal canals, or vagina.

19. • Other topical medications include nonabsorbable oral
pharmaceuticals (such as sucralfate or vancomycin) that act
on the gastrointestinal mucosa, drugs inhaled on the
bronchi (such as salbutamol or cromolyn sodium), and
irrigating solutions or gels (such as povidone iodine or
lidocaine) applied to the urethra.
• Deeper Tissue: By using a syringe and needle, it is possible
to reach some deep areas. However, the drug must be
administered in a method that allows for slow systemic
absorption. Examples of this include intra-articular injections
(such as hydrocortisone acetate in the knee joint), intrathecal
injections (such as lidocaine), and retrobulbar injections
(which administer hydrocortisone acetate behind the
eyeball). LOCAL paths.
• Arterial supply: Anticancer treatments can be injected into
the femoral or brachial arteries to localize the effect for limb
cancers. Close intra-arterial injection is used for contrast

20. SYSTEMIC ROUTE
• drug administered through systemic routes is
intended to be absorbed into the blood stream and
distributed all over, including the site of action,
through circulation:
o Oral Nasal
oSublingual Parenteral
oRectal
oCutaneous
oInhalation

21. ORAL
• It is the oldest It and commonest mode of drug
administration.
• It is safer, more convenient, does not need assistance,
noninvasive, often painless, the medicament need not be
sterile and so is cheaper.
• Oral administration is possible for both solid and liquid
dosage forms, including powders, tablets, capsules,
spansules, dragees, moulded tablets, and gastrointestinal
therapeutic systems, or GITs, as well as elixirs, syrups,
emulsions, and mixes.

22. SUBLINGUAL
• The medication-containing tablet or pellet is crushed
in the mouth and applied to the buccal mucosa, or it
can be inserted beneath the tongue. Only non-
irritating, lipid-soluble medications can be delivered
in this manner.
• A few minutes can be used to create effect after
reasonably quick absorption.Spitting the medicine out
is an option once the intended effect has been
achieved, if a little inconvenient.

23. • The main benefit is that medications with a high first pass
metabolism can enter the systemic circulation straight away
and avoid the liver. Sublingual doses of GTN,
buprenorphine, and desamino-oxytocin are administered.
• When a patient is unable to take tablets or when a speedy
onset of action is required, such as in an emergency, this
method of administration is especially helpful. But not all
medications are appropriate for sublingual delivery; some
can taste bitter or not absorb well via the oral mucous
membranes. Furthermore, using the right approach is
crucial to guaranteeing the medication's best absorption
and effectiveness.

24. RECTAL
• For a systemic effect, several irritating and
disagreeable medications can be inserted into the
rectum as suppositories or retention enema. This
method can also be applied if the patient is
unconscious or experiencing frequent vomiting.
• Though diazepam solution and paracetamol
suppository are quickly and consistently absorbed
from the rectum in children, absorption is slower,
irregular, and frequently unpredictable, making it
fairly uncomfortable and unpleasant.

25. CUTANEOUS
• Drugs that are highly lipid soluble can be
administered topically to the skin for a prolonged and
gradual absorption. The medication can be mixed
with an ointment and applied to a particular skin
location. Rubbing the preparation will improve
medication absorption.
• Transdermal therapeutic systems (TTS): These are
adhesive patches that come in a variety of sizes and
shapes (5–20 cm2) and are used to transfer drugs into
the systemic circulation through the stratum corneum
at a steady rate.

26. • The medication, either unbound or attached to a
polymer, is contained in a reservoir that is sandwiched
between an occlusive backing film and a rate-
regulating micropore membrane, the underside of
which has an adhesive smeared on it that has been
impregnated with a priming dosage of the
medication.

27. INHALATION
• For systemic action, volatile liquids and gases such as general
anesthetics are inhaled.
• The large surface area of alveoli is where absorption occurs; the
action happens extremely quickly.
• When medication is stopped, it diffuses again and is quickly
removed from the air.
• Thus, with actual time correction, controlled administration is
achievable. Ether is one of the irritant vapours that increases
secretion and causes respiratory tract inflammation.

28. NASAL
• Many medications can be easily absorbed through the
mucous membrane of the nose, bypassing the liver
and digestive acids.
• Only a few medications, such as GnRH agonists and
desmopressin sprayed or nebulized, have been
administered via this method, nevertheless. This
pathway is being explored for other peptide
medications, such as insulin, in addition to avoiding
the blood-brain barrier.

29. PARENTERAL
• Parenteral refers, traditionally, to the delivery of medication by
injection, which bypasses the enteral mucosa and delivers the
medication straight into the tissue fluid or blood.
• It gets beyond the limits of oral administration. Adv-Drugs act more
quickly and reliably; useful in emergency situations. There is no trigger
for vomiting or gastric discomfort. Even in patients who are comatose,
uncooperative, or who are vomiting, parenteral methods can be
used.There is no possibility of food or digestive juices interfering.

30. • Negatives: Parenteral injections are generally riskier than oral ones;
however, preparation should be sterilized and is more expensive; the
technique is invasive and painful; the majority of the time, assistance
from a caregiver is required (although self injections, such as insulin by
diabetics), there is a chance of local tissue injury.

31. INTRAMUSCULAR
• One of the huge skeletal muscles, such as the gluteus
maximus, rectus femoris, triceps, or the deltoid, is
where the medication is injected. Muscle is more
vascular (drugs absorbed in aqueous solution are
absorbed more quickly) and has a less abundant
supply of sensory nerves (light irritants can be
injected).
• Subcutaneous (s.c.) The medication is deposited in the
loose subcutaneous tissue, which is less vascular than
intramuscular tissue but richly supplied by nerves
(irritant drugs cannot be injected). Absorption of the
drug occurs more slowly in this tissue.

32. INTRAVENOUS
• The medication can be injected gradually over several
hours into one of the superficial veins, or
administered as a bolus (Greek: bolos-lump).The
medication enters the bloodstream directly and starts
working right away, making it very useful in an
emergency.
• Intradermal injection: This type of injection causes
scarring or many punctures of the epidermis through
the injection of a drug drop, or it raises a bleb (as in
the case of sensitivity testing or the BCG vaccine).This
route is only used for certain purposes.

33. AGONISTS, ANTAGONISTS( COMPETITIVE
AND NONCOMPETITIVE)
• Any cellular macromolecule that a neurotransmitter or
drug attaches to initiate operating is called a receptor.
• A receptor's natural purpose is to take part in
neurotransmission or physiologic control. Humanity
has discovered that medications may be used to
either activate or block these receptors in order to
achieve a range of outcomes.

34. • An antagonist is a substance that causes a receptor to
become active in order to replicate the physiological
signal molecule's effects.
• Agonist - An agent which activates a receptor to
produce an effect similar to that of the physiological
signal molecule.
• Competitive antagonism (equilibrium type) The
antagonist is chemically similar to the agonist,
competes with it (and binds to the same site to the
exclusion of the agonist molecules.

35. ADDICTION
• It is a pattern of compulsive drug use characterized by
overwhelming involvement with the use of a drug.
• Addiction is a complex and multifaceted condition that affects
millions of people worldwide, transcending age, gender,
socioeconomic status, and cultural backgrounds. It manifests
in various forms, including substance addiction (such as drugs
and alcohol), behavioral addiction (such as gambling, gaming,
or compulsive shopping), and even addiction to certain
emotions or behaviors (like love or exercise).

36. • Using and obtaining the substance come first.
Everything else comes second.
However, medications like as nalorphine cause
physical dependence without causing addiction in the
sense that users don't actively seek out narcotics.
• The need for a higher dosage of a medication to elicit
a particular response is referred to as tolerance.
Refractoriness is a term used to describe the loss of
therapeutic efficacy, which is a sort of tolerance.
Examples of this include the use of β2 agonists in
bronchial asthma and sulfonylureas in type 2 diabetes.

37. TOLERANCE
• One common adaptive biological phenomenon is
tolerance. Drug tolerance can be either natural or
artificial. For example, black people can tolerate
mydriatics, but rabbits are naturally less sensitive to
atropine. Within any given group, there are
individuals that exhibit hypo responsiveness to
specific medicines, such as alpha-adrenergic blockers
or alcohol.

38. TOLERANCE
• This happens when a person who was originally
responsive to treatment uses the substance
repeatedly.
• Most medicines have the potential to cause tolerance
in the body, but CNS depressants are one class of
pharmaceuticals where tolerance is most obvious.
• Tolerance development is favored by the drug's
continuous presence in the body. However, atropine,
digoxin, cocaine, sodium nitroprusside, etc. do not
cause a substantial tolerance to develop.

39. CROSS TOLERANCE
• As an example, alcoholics are comparatively tolerant
to barbiturates and general anesthetics. It is the
development of tolerance to pharmacologically
related medicines.
• The degree of cross-tolerance between two
medications increases with their proximity to one
another. For example, there is complete cross-
tolerance between morphine and pethidine but only
partial cross-tolerance between morphine and
barbiturates.

40. DEPENDENCE
• Drugs capable of altering mood and feelings are
liable to repetitive use to derive euphoria, recreation,
withdrawal from reality, social adjustment, etc.
• Drug dependence is a condition in which using drugs
for self-gratification—often in spite of health risks—is
prioritized over other necessities.
• Psychological dependence: This is defined as the state
in which a person feels that the substance is the only
way to reach their ideal level of wellbeing.

41. TACHYPHYLAXIS
• When a drug's doses are taken quickly after one
another and the reaction to the drug noticeably
decreases, this is referred to as rapid tolerance
development.
• This is typically observed with medicines that function
indirectly, including ephedrine, tyramine, and nicotine.
• These drugs work by causing the body to release
catecholamines at a rate that is faster than the body
can synthesise them, which causes the stores to run
out.

42. • Additional processes include compensatory
homeostatic adaptation,
desensitization/internalization, down-regulation of
the receptor, and/or the drug's gradual separation
from its receptor.

43. IDOSYNCRACY
• An idiosyncrasy refers to a distinctive or peculiar
feature or characteristic of a person, thing, or group,
especially one that is individual to them. It often
implies a unique trait or behavior that sets someone
or something apart from others.
• The drug interacts with some unique feature of the
individual, not found in majority of subjects, and
produces the uncharacteristic reaction.

44. • As such, the type of reaction is restricted to
individuals with a particular genotype . In addition,
certain bizarre drug effects due to peculiarities of an
individual (for which no definite genotype has been
described) are included among idiosyncratic
reactions, e.g.: • Barbiturates cause excitement and
mental confusion in some individuals.
• Quinine/quinidine cause cramps, diarrhoea, purpura,
asthma and vascular collapse in some patients. •
Chloramphenicol produces nondose-related serious
aplastic anaemia in rare individuals.

45. PHARMACOKINETICS: MEMBRANE
TRANSPORT
• All pharmacokinetic processes involve transport of the
drug across biological membranes. Biological
membrane.
• Biological membranes carry out functions that are
indispensable for life.
• They also give shape to cell creating matrix for
insertion of proteins storing and transmitting energy

46. BIOLOGICAL MEMBRANE
• They provide barrier against extracellular
environment.
• They also give shape to cell, creating matrix for
insertion of proteins, storing and transmitting energy,
receiving and amplifying signals.

47. • All biological membranes are composed of mainly
lipids and protein molecules.
• Three major types of lipid membranes are:
o Phospholipids: The most abundant.
o Cholesterol: Responsible for stabilizing membrane.
o Glycolipid: found at external surface of membrane.

48. • All the lipids are described being amphipathic as they
have a hydrophilic and hydrophobic end to molecule.
• The proteins within membrane are largely concerned
with transport of molecules across membrane.

50. • Drugs are transported across membrane by:
o Passive Diffusion
o Filtration: for low molecular weight ( less than 100)
o Specialized transport.
o Active transport.

51. PASSIVE DIFFUSION
• The drug diffuses across membrane in direction of its
concentration gradient. ( High to low)
• The membrane playing no active role in the process.
• This is the most important mechanism of majority of
drugs.
• The drug moves from high concentration to low
concentration until equilibrium is maintained between
extracellular and intracellular fluid.
• It does not require energy and depends on
concentration.

53. • Lipid soluble drugs diffuse by dissolving in lipoidal
matrix of the membrane the rate of transport being
proportional to lipid.
• Water partition coefficient of the drug.
• More lipid soluble drug attains higher concentration
in membrane and diffuses quickly.
• Also, greater difference in concentration of drug on
two sides of membrane. Faster is its diffusion.

54. • Filtration: for molecule of low molecular weight (less than
100) through 7 Å pores of membrane (1micrometer = 10000
Angstrom) Example : Urea , ethylene glycol (additives).
• Bulk flow : Passage across capillary wall which pore size of
40Å.
• Active transport: Require energy (ATP). It work against
concentration gradient ( Higher to lower concentration).
Example : Methyldopa, Levodopa.
• Facilitated diffusion : through carrier proteins.
• Endocytosis ( outside to inside) and exocytosis( Inside to
outside) through pinocytosis, phagocytosis.

56. FILTRATION
• Filtration transport refers to the movement of
substances through a filter due to a pressure gradient.
This process is commonly utilized in various industries
and applications, including water purification, air
filtration, and chemical processing.
• Filtration is passage of drug through aqueous pores in
membrane or paracellular spaces.
• This can be accelerated if hydrodynamic flow of
solvent is occurring under hydrostatic or osmotic
pressure gradient. Eg: Across capillaries.,

58. SPECIALIZED TRANSPORT
• This can be carrier mediated or by vesicular transport.
• Endocytosis & Exocytosis

60. ABSORPTION
• It is transfer of drug from site of administration to the
bloodstream.
• The rate and extent of drug absorption depend on
environment where the drug is absorbed, chemical
characteristic of drug and route of administration (
which influence bioavailability.

61. FACTORS AFFECTING DRUG
ABSORPTION
• Lipid solubility of drug.
• pH of medium ( intestine or stomach).
• pKa of drug.

62. LIPID SOLUBLITY OF DRUG
• Drugs which are lipophilic cross the membrane.
• Drugs which are Lipophobic have problem crossing
membrane.
• This is major source of variation in drug diffusion.
• Polar drugs are water soluble. They cannot absorbs
biological membranes.
• Lipid soluble: Non ionized (Nacl)
• Water soluble: Ionized (Na+, Cl-).

63. EFFECT OF PH IN DRUG ABSORPTION
• Acidic drug is better absorbed in acidic medium.
• Basic drug is better absorbed in basic medium.
• Acidic drugs (eg: Aspirin) are better absorbed in
stomach in acidic medium.
• Basic drugs (eg: Morphine) are better absorbed in
intestine in basic medium.

64. BIOAVAILABLITY
• It is rate of extent to which an administered drug
reach systemic circulation.
• Or bioavailability is rate and extent of drug absorbs
from that reach to systemic circulation.
• Example: 100 mg of drug is administered orally & 70
mg is absorbed unchanged, the bioavailability is 70 %.

65. OBJECTIVES OF BIOAVAILABLITY
STUDIES
• Primary stage of development of suitable dosage
form.
• Determination of influence of excipients ( stability and
solubility) and interaction with other drugs on the
efficiency of absorption.

66. INTESTINAL
PERMEATION
SOLUBLITY
FIRST PASS
METABOLISM
ORAL BIOAVAILABLITY

67. FIRST PASS HEPATIC METABOLISM
• When drug is absorbed from GI tract, it enters portal
circulation before entering systemic circulation.
• If drug is rapidly metabolized in liver or GIT wall
during this initial passage, the amount of unchanged
drug entering in systemic circulation is decreased.
• This is referred to as first pass metabolism.
• Cytochrome p450 enzymes metabolize many drugs.

69. • First pass metabolism by intestine or liver limits the
efficacy of many oral medications.
• For example, more than 90 % of nitroglycerin (HF,
HBP) is cleared during first pass metabolism.
• Hence it is primarily administered via sublingual or
transdermal route.
• Drugs with high first pass metabolism should be
given in doses sufficient to ensure that enough active
drug reaches desired site of action.

70. DISTRIBUTION
• Drug distribution is process by which drug reversibly
leaves bloodstream and enters extracellular fluid and
tissue.
• Phases of distribution:
 First phase:
• Reflect cardiac output & blood flow.
• Thus heart, liver, kidney and brain receive most of
drugs during first few minutes after absorption.

71. • Second Phase:
• Deliver to muscle, skin, adipose is slower and involves
a far large fraction of body mass.
 Drug Reservoir:
• Body compartment where drug can accumulate are
reservoirs and have dynamic effect on drug
availability.
 Plasma proteins (Albumins) are reservoirs (blind
drug).
Cellular reservoirs
1. Adipose (Lipophilic drug)
2. Bone (crystal)

72. DRUGS BINDING PRIMARILY TO
ALBUMIN
• Barbiturates
• Benzodiazepines
• Digitoxin
• Penicillins

73. VOLUME OF DISTRIBUTION
• Volume of distribution (Vd) defined as fluid volume
that is required to contain entire drug in body at same
concentration measured in plasma.

75. METABOLISM
• Drug metabolism is term used to describe
biotransformation of pharmaceutical substance in body so
that they can be eliminated more easily.
• It is enzymatic conversion from one chemical form of
substance to another.
• It is an essential pharmacokinetic process which converts
lipid soluble or non polar compounds to water soluble or
polar compounds that they are excreted through various
processes.

76. PHASES OF METABOLISM
• Phase 1: Non synthetic reactions such as cleavage
(oxidation, reduction, hydrolysis), formation or
modification of a function group.
• Phase 2: Synthetic reactions such as conjugation with
an endogenous substance (eg: sulphate, glycine,
glucuronic acid).
• Example:
• Oxidation: phenytoin
• Reduction: Benzodiazepines

78. PHASE 1 AND PHASE II ENZYMES
 Phase 1 Enzymes:
• Cytochrome p450 esterase, Alcohol dehydrogenase,
Monoamine oxidase.
 Phase II Enzymes:
• Uridine diphosphate glucanosyl transferase, sulpho
transferase

79.  MICROSOMAL ENZYMES:
• Found in smooth metaplasmic reticulum of liver cells.
• Example: CYP-450, mono oxygenase.
 NON MICROSOMAL ENZYMES
• Found in cytoplasm and mitochondria of liver cells.
• Eg: Alcohol dehydrogenase.

80. DRUGS AND THEIR METABOLITES ARE
EXCRETED IN
• Urine: Drug excretion in urine occurs in kidney.
• It is most important channel of excretion for majority
of drugs.
• Faeces: Apart from unabsorbed fraction, most of drug
present in Faeces is derived from bile.
• Liver actively transports into bile organic acids.

81. • Milk: The excretion or drug in milk is not important
for mother.
• Most drugs enter breast milk by passive diffusion.
• As such lipid soluble and less protein bound drugs
cross better.
• Milk has lower Ph (7.0) than plasma, basic drugs are
somewhat more concentrated in it.