2. Antihistamines
• Antihistamines are the drugs used in the treatment od
allergic disorders and some other conditions.
Mechanism of action
• These drugs block the effect of histamine and its
receptors. They also provide some sort of sedation.
There are four types of antihistamines drugs.
1. Highly sedatives.
2. Moderate sedatives.
3. Mild sedatives.
4. Non sedatives.
3. Drug Example & Doses
S. No Drugs Doses
Highly Sedative
1 Diphenhydramine 25-50mg
2 Promethazine 25-50mg
3 Hydroxyzine 25-50mg
Moderate Sedatives
4 Medizine 25-50mg
5 Buclizine 25-50mg
6 Phenivamine 25-50mg
7 Cyproheptadine 4mg
5. Indications/Uses
• Allergic reactions (Hay fever, Vasomotor rhinitis urticaria, asthma,
Anaphylaxis).
• Because of their anticholinergic actions they are used as
antiemetics and useful in motion sickness.
• As hypnotics, Mild sedative/anxiolytics.
• Parkinsonism.
Contraindications
• Hypersensitivity.
• Lactation.
• Hypokalemia.
• Neonate.
• Coma. Special precautions in acute asthma and pregnancy, elderly,
epilepsy.
6. Adverse effects
• Drowsiness
• Dryness of mouth.
• Blurring of vision.
• Urinary retention.
• Constipation.
• Delirium.
• Convulsions.
• Severe toxicity may causes death to cardiac and respiratory
failure
7. MUCOLYTICS
• These drugs reduced the viscosity of sputum that leads
to easily expel the sputum.
Mechanism of Action
• Decrease mucous viscosity by breaking or altering
mucoproteins present in sputum.
Indications
• Totreat abnormal viscous, or thick and hard
mucus.
• As an antidote for acetaminophen overdose
(acetylcysteine).
8. Drug example &
Doses
S No. Drugs Doses
1 Acetylcysteine 2.5 ml of 10-20% solution given by
inhalation or nebulization
2 Bromhexine 8-16 mg TDS.
Contraindications
• Hypersensitivity to these drugs.
• Cautiously in elderly, pregnant or breastfeeding mothers
10. Decongest ants
• A Decongestant drugsused to relieve nasal congestion
in upper respiratory tracts.
Mechanism of action
• Decongestants are sympathomimetic drugs that act by
stimulating the α (alpha) – adrenergic receptors.
• The decongestant effect due to vasoconstriction of the
blood vessel in the nose sinuses etc. the
vasoconstriction effect reduces swelling or inflammation
and mucous formation in the nasal passage and make it
easier to breath
11. Drug examples and doses
S. No. Drugs Doses
1 Oxymetazoline
hydrochloride
0.05% solution or nasal spray.
2 Phenylephrine
hydrochloride
10 mg
3 Pseudoephedrine
hydrochloride
60 mg.
12. Indications /uses
• For temporary relief of nasal congestion due to
common cold.
• Hay fever.
• Sinusitis.
• Upper respiratory tract allergens.
• Topromote nasal and sinus drainage.
13. Contraindications/precautions
• Hypersensitivity to these drugs.
• MAO (Monoamine oxidase) inhibiters drugs therapy.
• Use cautiously in older age patient they are more likely
to experience adverse reaction.
• Nasal contestant should not be used for more than
three days, and oral decongestant should not used
more than 7days because prolonged use will result
in rebound congestion.
15. Drug interactions
• If given with other sympathomimetic amines may
increase central nervous system stimulation.
• If given with MAO inhibitors may cause severe
hypertension.
16. Drugs for cough
• The drug which used in cough are:
1. Antitussive.
2. Expectorants.
3. Bronchodilators.
17. Antitussives (Cough center suppressant)
a) Opioids – Codeine, pholcodine.
b) Non opioids – Noscapine,
dextromethorphan.
c) Antihistamine – Chlorpheniramine
diphenhydramine.
18. Antitussives – Introduction
• They are used to suppress dry cough mostly
because their aim to control rather than
eliminate cough. These are also called cough
center suppressants.
Mechanism of action
• These are the drugs that act in the CNS to
increase threshold of cough center.
19. Drug example & Doses
S.
No
Drugs Doses
1 Codeine (Opioids) 15-60mg up to every 4 hrs
2 Noscapine (Non opioids) PO 15-30 mg itramin maleate
3 Dextromethorphan (Non
opioids)
10-30mg PO 4-8hrs max.
120/day
4 Chlorpheniramine
(Antihistamine)
4 mg PO 4-6 hrly
5 Diphenhydramine
(Antihistamine)
25 mg PO 4hrly not to exceed
150 mg / day.
22. Expectorants
a) Bronchial secretion enhances – sodium or
potassium citrate, potassium iodide,
ammonium chloride.
b) Mucolytic agents – bromhexine ambroxol,
acetylcysteine.
23. Expectorants
• These drugs help in removal of secretions of
respiratory tract and mucolytic agents
produce liquification of mucous making
expectoration easier.
24. Mechanism of action
• They increase bronchial secretions or
reduce its viscosity, sodium and
potassium citrate increase bronchial
secretion by salt action also these drugs
stimulate gastric mucosa or directly acting
on mucous membrane of lungs to increase
the secretion of mucous.
27. Contraindication/precautions
• History of peptic ulceration.
• Asthmatic patients.
• Severe hepatic or renal function.
Drug interactions
• They may increase the risk of bleeding
when used with anticoagulants.
