This document discusses various topics related to adverse drug reactions and rational drug use. It defines adverse drug reactions and outlines different types including side effects, toxic effects, intolerance, idiosyncrasy and allergic reactions. It also discusses drug dependence, teratogenicity, iatrogenic diseases and provides examples of drugs affecting different organ systems. The document emphasizes the importance of rational drug use by defining therapeutic objectives, considering patient factors, choosing appropriate drugs and monitoring treatment. It highlights the need to avoid irrational drug combinations that are promoted without clear benefits.

1. B.Chakrapani M.pharm
Associate professor
Department of pharmacology
Ananthapuram
9618279507

2. Adverse drug reactions
All drugs produce unwanted effects.
Who has defined an adverse drug reaction as
“an response to a drug that is noxious and
unintended and that occurs at doses used in
man for prophylaxis ,diagnosis therapy .”

9. All drugs can cause adverse effects .
Some patients are more likely to develop
adverse effects to drugs.
Nurses should have a good knowledge about
allergic reactions .
Because some of them like anaphylaxis may
be rapidly fatal and require immediate
treatment to prevent death.

11. Side effects
Side effects are un wanted effects of a drug that are
extensions of pharmacological effects and are seen
with the therapeutic dose of the drug.
They are predictable, common and can occur in all
people.
E.g.: Hypoglycemia due to insulin;
Hypokalemia following Furosemide .
Pharmacovigilance :deals with the epidemiologic
study of adverse effects .
It is a branch of pharmacoepidemology.

12. Toxic effects
Toxic effects are seen with higher doses of the
drug and can be serious , e.g. morphine causes
respiratory depression in over dosage.

13. In tolerance
 Inability to tolerate
Drug intolerance is the in ability of a person to
tolerate a drug and is un predictable.
Patients show exaggerated response to even small
doses of the drug.
E.g. vestibular dysfunction after a single dose of
streptomycin seen in some patients.

14. idiosyncrasy
Genetically determined abnormal reaction to a
drug.
e.g. primaquine and sulfonamides
The person may be highly senstitive even to
low doses of a drug or highly insenstive even
to high doses of the drug.

15. Types of allergic reactions and their mechanisms
Allergic reactions are grouped into 4 types –type I
to type IV.
The basis of allergic reactions may be humoral
(antigen –antibody reactions) or cell mediated
immunty.
Drugs can induce both types of allergic reactions .

16. Type I anaphylactic reaction
Type II cytolytic reactions
Type III arthus reaction
Type IV delayed hypersensitivity reactions

17. Iatrogenic diseases (physician induced)
These are drug induced diseases.
Even after the with drawn ,toxic effects can
persist ,e.g. isoniazid –induced hepatitis ;
chloroquinine induced retinopathy.

18. Drug dependence
Drugs that influence the behavior and mood are
often misused to obtain their pleasurable effects.
Repeated use of such drugs result in dependence.
Several words like drug abuse, addiction, and
dependence are used confusingly.
Drug dependence is a state of compulsive use of
drugs through the person is aware of risks associated
with its use.

19. Dependence could be psychological or physical
dependence .
Psychological dependence is compulsive drug
seeking behavior to obtain its pleasurable effects ,
Example: cigarette smoking .

20. teratogenicity
Teratogenicity is the ability of a drug to cause
abnormalities in the fetus when administered
to the pregnant lady.
The sedative thalidomide taken during early
pregnancy for relief from morning sickness,
resulted in thousands of babies being born with
sea limbs.

22. EXAMPLES OF DRUGS AFFECTING VARIOUS ORGAN
SYSTEMS
ORGAN SYSTEM AFFECTED EXAMPLES
1.Hepatotoxicity Isoniazid,pyrazinamide,parace
tamol,chloropromazine,6-
mercaptopurine,halothane,etha
nol,phenylbutazone.
2.Nephrotoxicity Analgesics , Aminoglycosides
, Cyclosporine, Cisplatin.
3.Ototoxicity Aminoglycosides,frusemide
4.Ocular toxicity Chloroquine, Ethambutol
5. Gastrointestinal system Opioids, broadspectrum

24. Rational drug use
Once a patient is diagnosed to have a particular
disease and needs to be treated with drugs , the
specific therapeutic objective should be defined .
For example : In hypertension the objective is to
bring down the B.P to a particular level in order to
prevent complications of prolonged hypertension.

30. When many drugs are available for the treatment
of a particular condition , the right choice should
be carefully made.
For example : hyperacidity and mild gastritis may
be managed with antacids.
When not controlled a H2 receptor blockers like
ranitidine helps.
Only more severe cases require to be treated with
omeraprazole.

31. Patient factors Including age, presence of other
diseases , renal and liver function , other drugs
being administered and cost of therapy should be
considered.
Newer drugs are all expensive .
When less expensive older drugs available ,they
should be preferred to the newer ones.

32. Through ,human insulin is the rational choice
for all diabetics who need insulin, majority of
patients in the developing countries like india
cannot afford such an expensive medication
for the rest of their lives.
Hence ,conventional insulin's are still
preferable in them –unless contraindicated.

33. The dose and the duration of treatment should be
determined.
When long term treatment is required , the
regular review and monitoring of treatment
should be planned .
The therapeutic point should be defined.

34. When a combination of drugs is to be admi
nistered, the guidelines like better therapeutic
benefit ,avoiding drugs with overlapping adverse
effects and cost of therapy should be borne in
mind.
Equally important is to avoid irrational
combination of drugs.

35. The flourishing drug industry often comes out
with absurd combinations of drugs .
They serve no useful purpose , are more
expensive and unnecessary , but are vigorously
promoted and unfortunately often prescribed by
doctors .

36. Such examples:
1. Amoxicillan with Cloxacillin.
2. Ibuprofen with pracetamol
3. Diclofenac +nimesulide
4. Ciprofloxaciln +Tindidazole

37. THERAPEUTIC DRUG MONITORING
Measurement of the concentration in body
fluids can assist in individualizing therapy with
selected drugs.
Determination of the concentration of a drug is
particularly useful.
The relationship exists between the
concentration of drug in plasma and the
desired therapeutic effect.

38. The toxic effect to be avoided.
The range of plasma levels between that required
for efficacy and that at which toxicity occurs for a
given individual is designated the therapeutic
window.
The drug produces effects, intended or unwanted,
that are difficult to monitor.
The concentration required to produce the
therapeutic effect is close to the level that causes
toxicity (i.e., there is a low therapeutic index).