Nasal decongestant and Respiratory stimulants,Classification-Phenylepherne,Phenylpropanolamine,α1 agonist,α2 receptors agonists/ Imidazoline compounds,Side effects,Respiratory Stimulants,Role of analeptics,Doxapram . Snehal chakorkar pharmacology

1. Nasal Decongestant &
Respiratory stimulants
Miss Snehal S. Chakorkar (M.pharm)
Dept Of Pharmacology
5-Oct-19 1

2. Introduction:Nasal Decongestant
5-Oct-19 2
Definition: “These are α agonists which on topical application as
dilute solution (0.05–0.1%) produce local vasoconstriction.”
Simply, nasal decongestants are the drugs that reduce congestion of
nasal passages, which in turn open clogged nasal passages and
enhances drainages of the sinuses.
Nasal decongestants are prescribed in patients with allergic or
vasomotor rhinitis and in acute rhinitis in patients with upper
respiratory infections.
Major limitation with chronic nasal decongestants therapy or
withdrawal of therapy is loss of efficacy, “rebound” hyperemia, and
worsening of symptoms may due to receptor desensitization and
damage to the mucosa.

3. 5-Oct-19 3
Classification Of Nasal Decongestant :
A. Depends upon duration of action;
1. Short acting decongestants administered topically;
Ex-Phenylepherne,
Phenylpropanolamine.
2. Long acting decongestants administered orally ;
Ex-Ephedrine,
Pseudoephedrine,
Naphazoline.
3. Long acting topical decongestants;
Ex- Xylometazoline,
Oxymetazoline

4. B. Depends upon α Receptor agonists/
Sympathomimetic decongestants :These agents used
with great caution in patients with hypertension and in men with
prostatic enlargement, and they are contraindicated in patients
who are taking MAO inhibitors.
1. α1 agonist:
Ex- Phenylephrine,
Phenylephrine .
2. α2 receptors agonists/ Imidazoline compounds :
Ex-Clonidine.
Naphazoline,
xylometazoline
oxymetazoline.
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5. A. α1 agonist:
Definition: “These drugs probably decrease resistance
to airflow by decreasing the volume of the nasal mucosa;
this may occur by activation of αlpha receptors in venous
capacitance vessels in nasal tissues that have erectile
characteristics”
Ex- Phenylephrine.
At high concentration it has negligible β action.
These are less likely to induce mucosal damage but on
I/V infusion causes marked arterial vasoconstriction
causes raises BP 5-Oct-19 5

6. Phenylephrine & epinephrine:
Chemically, phenylephrine differs from epinephrine only
in lacking a hydroxyl group at position 4 on the benzene
ring.
Pseudoephedrine is less potent than ephedrine in
producing tachycardia, increased blood pressure, and
CNS stimulation.
Uses:
Used as nasal decongestant in acute rhinitis.
Topically used as mydriatic when cycloplegia is not
required. It reduces intraocular tension by constricting
ciliary body blood vessels.
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7. 5-Oct-19 7
B. α2 receptors agonists/ Imidazoline
compounds :Ex- Clonidine, naphazoline, xylometazoline and
oxymetazoline.
α2 receptors may mediate contraction of arterioles that supply
nutrition to the nasal mucosa but intense constriction may cause
structural damage to the mucosa.
They may cause initial stinging sensation (specially naphazoline).
Regular use of these agents for long periods should be avoided
because mucosal ciliary function is impaired: atrophic rhinitis and
anosmia can occur due to persistent vasoconstriction
They can be absorbed from the nose and produce systemic effects,
mainly CNS depression and rise in BP. These drugs should be used
cautiously in hypertensives and in those receiving MAO inhibitors.
.

8. 5-Oct-19 8
Drug Name Information
Clonidine It is an imidazoline derivatives , was originally tested
as a vasoconstrictor acting at peripheral α2 receptors.
During clinical trials as a topical nasal decongestant,
clonidine was found to cause hypotension, sedation,
and bradycardia.
Pharmacological Effects
It changes in blood pressure and heart rate.
Intravenous infusion of clonidine causes an acute rise
in blood pressure.
Example:
They have a longer duration of action (12 hours) than
ephedrine.

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Common mechanism of action:
Decongestant
α 1 adrenergic receptor
stimulate
Release
Enhansing noradrenaline and adrenaline activity
vasoconstriction and constricting nasal vasculature
Decongestion of nasal mucosa and paranasal sinuses
Reduced inflammation/ swelling and mucus formation in these areas.
Results in

10. Side effects:
1.The effects are not limited to the nose, and these
medicines may cause hypertension (high blood pressure)
through vasoconstriction; it is for this reason that people
with hypertension are advised to avoid them.
2.common side-effects include
3.Sleeplessness,
4.Anxiety,
5.Dizziness,
6.Excitability and nervousness.
7.Topical nasal or ophthalmic decongestants quickly
develop tachyphylaxis (a rapid decrease in the response
to a drug after repeated doses over a short period of time).
Long-term use is not recommended, since these agents
lose effectiveness after a few days.5-Oct-19 10

11. 5-Oct-19 11
Introduction: Respiratory Stimulants
Definition: “These are drugs which stimulate
respiration and can have resuscitative value ( property
to restore consciousness ) in coma or fainting.”
At low dose they stimulate respiration, but margin of
safety is narrow; at high dose the patient may get
convulsions while still in coma.
Mechanical support to respiration and other measures to
improve circulation are more effective and safe.

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Role of analeptics: Role in therapeutics is very
limited used in conditions like;
(a) Overdose with sedatives or hypnotic untill
mechanical ventilation is instituted.
(b) Suffocation on drowning, acute respiratory
insufficiency or in postanesthetic respiratory
depression.
(c) Apnoea in premature infant.
(d) Failure to ventilate spontaneously after general
anaesthesia.
(e) idiopathic hypoventilation.

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Classification of respiratory stimulants:
A) Drugs directly activating respiratory centre:
Ex-Caffine, Bemegride, Etimizole.
B) Drugs acting by reflex action:
Ex-Cytiton,Lobeline.
C) Drugs shows mixed type of action:
Ex-Nikethamide, Carbogen.

14. 5-Oct-19 14
Doxapram
It acts by promoting excitation of central neurones.
At low doses it is more selective for the respiratory
centre than other analeptics.
Respiration is stimulated through carotid and aortic body
chemoreceptors as well. Falling BP rises.
Continuous i.v. infusion of doxapram may abolish
episodes of apnoea in premature infant not responding to
theophylline.
Dose: 40–80 mg i.m. or i.v.; 0.5–2 mg/kg/hr i.v. infusion.
CAROPRAM 20 mg/ml in 5 ml amp.

15. Reference:
 Rang H.P. and Dale M.M.: Pharmacology, Churchill
Livingstone, Edinbergh.
 Katzung B.G.: Basic and Clinical Pharmacology,
Lange Medical Publications, California.
 Craig C.R. and Stitzel R.E.: Modern Pharmacology,
Little Brown and Co., Boston.
 Bowman W.C. and Rand M.J.: Textbook of
Pharmacology, Blackwell Scientific Publications,
Oxford.
 P.N Bennett & M J Brown: Clinical Pharmacology,
Churchill Livingstone, Edinburgh.
 Tripathi K.D.: Essentials of Medical Pharmacology,
Jaypee Brothers, Medical Publishers, New Delhi.
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16. Any query don’t hesitate to contact & If like then comment in box5-Oct-19 16