Adverse drug reactions - Types. Definition, teratogenicity

1. Adverse Drug Reactions
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Dr. Jervin

2. Defintion
• Any undesirable or unintended
consequence of drug administration
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3. Incidence
• 10-25%
• R/F Multiple drug therapy, elderly
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4. Classification
• A- Augmented (Predictable)
• B- Bizarre (Unpredictable)
• Minor- negligible
• Major- requires Rx
• Severe- intensive care
• Lethal- death
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5. Pharmacovigilance
• Science & activities related to
1. Detection
2. Assessment
3. Understanding
4. Prevention
Of ADR or any drug related problems
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6. 1. Side effects
• @therapeutic doses
• Predictable
• Rx -> reduction in dose
• E.g.
– Atropine – preanaesthetic medication
– Codeine – cough -> constipation (traveler's
diarrhea)
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7. 2.Secondary effects
• Indirect consequence of primary action
• E.g.
Tetracyclines-> Supression of bacteria
flora-> superinfections
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8. 3. Toxic effects
• @ excessive doses
• Absolute / relative
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9. 4. Intolerance
• @ therapeutic doses
• Appearance of characteristic toxic effects
of a drug in an individual
• Low threshold for drug
• E.g. carbamazepine -> ataxia
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10. 5. Idiosyncrasy
• Genetically determined abnormal
reactivity to a chemical
• E.g. barbiturates -> excitation & confusion
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11. 6. Drug allergy
• Immunologically mediated reactions
• Body considers drug as allergen
• Seen in small proportion of population
• Types : I , II, III, IV
• Rx :
 O2,
 Inj. Adrenaline 0.5mg (1:1000) im / 1:10,000 iv
 Antihistamines
 Glucocorticoids
• Prevention
– Skin tests (type I)
• Eg . Penicillins
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12. 7. Photosensitivity
• Cutaneous reactions resulting from drug
induced sensitization of skin to UV rays
• Phototoxic
• Photo allergic
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13. Phototoxic
• Eg :
a/c : Tetracyclines
c/c : naldixic acid, Fluoroquinolones,
sulfones, Amiodarone.
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Drug/metabolite accumulates in skin
Absorbs light (Short wave length)
Photo biochemical reactions
Erythema, oedema , blisters
Hyperpigmentation, desquamation

14. Photoallergic
Drug
CMI
Papular,/eczematous contact dermatitis
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Light
(long wavelength)
Eg:
Sulfonamides
Sulfoylureas
Chloroquine

15. 8. Drug dependence
• Psychological dependence
– E.g. Opioids, cocaine
• Physical dependence
– E.g. Opioids, barbiturates, alcohol
• Drug abuse
• Drug addiction
• Drug habituation
– E.g. Tea, coffee, smoking
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16. 9. Drug withdrawal
• Adverse consequences in sudden
interruption of therapy
• E.g. Angina worsens when β-blockers
stopped suddenly
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17. 10. Teratogenicity
• Capacity of a drug to cause foetal
abnormalities when given to pregnant
mother
• 3 Stages:
– Fertilization & Implantation (0-17)-Failure of
pregnancy
– Organogenesis† (18-55)- deformities
– Growth & development (56-) : Developmental
& functional abnormalities
• Avoided in pregnancy
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18. Risk category
• A – Human studies – No risk
• B - Animal Studies – No risk
• C – Potential benefit, no proper evidence
• D- Evidence of human foetal risk but
potential benefits outweigh
• X – potential risk
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19. Teratogenic drugs
• T- Thalidomide
• E- Epileptic drugs[Phenytoin, Phenobarbitone,
Carbamazepine, Valproate]
• R- Retinoids
• A- ACE –s; Alcohol ; Anticancer
• T- Thyroid drugs
• O- OCPs & Hormones
• G- Gonadotrophins
• E- Ergometrine
• N- NSAIDs- Aspirin, Indomethacin
• I-
• C- Coumarin , Warfarin
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20. • S- Sulfonamides
• A- Aminoglycosides
• F- Fluoroquinolones
• E- Erythromycin
• C- Clarithromycin
• T- Tetracycline
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21. 11. Mutagenicity & Carinogenicity
• Capacity of a drug to cause genetic defects
• Capacity of a drug to cause cancer
• Eg:
–Anticancer drugs
–Radioisotopes
–Tobaco
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22. 12. Iatrogenic diseases
• Drug induces diseases
• Eg ;
 Peptic ulcer- salicylates
 Parkinsonism – Phenothiazines, antipsychotics
 Hepatitis - isoniazid
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23. Dental adverse effects
• Xerostomia : atropine
• Oral candidiasis : Corticosteroids
• Gingival swelling : Phenytoin
• Oral ulcers : Aspirin
• Tooth discolouration : Tetracyclines
• Metallic taste : Metronidazole
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