Pharmacology for Dentistry

234 Section 5/ Autacoids

two isozymes of phosphodiesterase (PDE III
and to a lesser extent, PDE IV) while non-bron-
chodilator prophylactic actions are mediated
through one or more different molecular mech-
anisms, that do not involve inhibition of PDE
III or antagonism of adenosine receptors. Theo-
phylline increases the force of contraction of
diaphragmatic muscles.

It is well absorbed orally. It is distribut-
ed to all tissues and is 50% plasma protein
bound. It is extensively metabolized in
liver by demethylation and oxidation. Only
10% is excreted unchanged in urine.

Adverse Effects

Side effects are usually associated with
the increasing serum concentration of
theophylline and includes nausea,
vomiting, headache, insomnia, tachypnea,
epigastric pain, palpitation, hypotension,
irritability. Higher doses can cause
persistent vomiting, cardiac arrhythmias,
intractable seizures, tachycardia. Other
side effects include alopecia, hyper-
glycemia, inappropriate ADH syndrome,
rash.

ANTICHOLINERGICS

Anticholinergics, like atropine and its deriv-
ative ipratropium bromide block cholin-
ergic pathways that cause airway constric-
tion. They may provide added bronchodi-
lator effect in patients who are receiving
beta 2 -adrenergic agents for asthma.

The detailed pharmacology is discussed
in chapter ‘Cholinergic blocking agents.’

MAST CELL STABILIZERS

SODIUM CROMOGLYCATE

It is a synthetic chromone derivative, highly

effective in preventing asthma attacks. It in-

hibits degranulation of mast cells by trig-

ger stimuli. It also inhibits the release of

various asthma provoking mediators e.g.

histamine, leukotrienes, platelet activating

factor (PAF) and interleukins (IL’s) from mast

cells. It prevents the late response and sub-

sequent bronchial hyperresponsiveness by

acting on inflammatory cells such as mac-

rophages or eosinophils. It does not produce

bronchodilatation and also does not antago-

nize the constrictor effect of histamine etc.

therefore not found beneficial in acute attack

of asthma and used for prophylaxis only.

Sodium cromoglycate is not absorbed

orally and is to be administered by aerosol.

Only a small fraction of inhaled drug is ab-

sorbed systemically and it is rapidly excret-

ed unchanged in urine and bile.

Adverse reactions reported are bron-

chospasm, throat irritation and rarely head-

ache, dizziness, rashes and nasal congestion.

Therapeutic Uses

1. Bronchial asthma: It is used for pro-
   phylactic treatment of bronchial
   asthma.


2. Allergic rhinitis: Two percent aqueous
   nasal spray (FINTAL nasal spray) is
   used for nasal decongestion although
   it is not a nasal decongestant.


3. Allergic conjunctivitis: Two percent
   aqueous eye solution (FINTAL eye