Anticholinergic drugs for optometry.

2. • At the end of the lecture, the students must
be able to learn
– What are antimuscarnic agents and why they are
named as?
– What is the classification?
– What are the actions of those agents on eye?
– What are the important pharmacology (MOA, PA,
uses, precaution, preparations) of each individual
agents on eye and important untoward effects?
– What are the important clinical notes in using
mydriatics?

3. • What is the classification?
• What are the actions of those agents on eye?
• What are the important pharmacology (MOA, PA,
uses, precaution, preparations) of each individual
agents on eye and important untoward effects?
• What are the important clinical notes in using
mydriatics?

4. • Anticholinergics
• Parasympatholytics
– Drugs that block the muscarinic receptor
mediated response of parasympathetic nervous
system.

5. • What are antimuscarnic agents and why they are
named as?
• What are the actions of those agents on eye?
• What are the important pharmacology (MOA, PA,
uses, precaution, preparations) of each individual
agents on eye and important untoward effects?
• What are the important clinical notes in using
mydriatics?

6. • Natural alkaloids
– atropine
– Hyoscine
• Synthetic compounds
– Homatropine
– Cyclopentolate
– Tropicamide

7. • What are antimuscarnic agents and why they are
named as?
• What is the classification?
• What are the important pharmacology (MOA, PA,
uses, precaution, preparations) of each individual
agents on eye and important untoward effects?
• What are the important clinical notes in using
mydriatics?

9. • Cycloplegic are drugs that paralyse the
ciliary muscle by blocking the “M”
receptors
(that are normally stimulated by the
release of acetylcholine from the nerve
endings of the parasympathetic system. )

10. • As parasympathetic nervous system also innervates
the pupil sphincter muscle, cycloplegia must be
accompanied with mydriasis.
• Cycloplegics are used to prevent or reduce
accomodation during refraction and also as
adjunct therapy in the treatment of certain
diseases of the anterior segment of eye.

11. • Mydriatics dilate the pupil to facilitate a more
thorough examination of the fundus, lens and
vitreous.

12. • What are antimuscarnic agents and why they are
named as?
• What is the classification?
• What are the actions of those agents on eye?
• What are the important clinical notes in using
mydriatics?

14. • MOA
– Competitive antagonism of ACh
at muscarinic receptor
• Pharmacological action
– On focusing the eye
• Mydriasis
• Cycloplegia
• Reduction in tear flow
• Increase IOP
– Has many pharmacological actions over the whole body.

16. • MOA
– Inhibition of circular muscle of iris, resulting pupil
dilation.
• Onset and duration
– Takes 30-40 mins for mydriasis to occur
– Last at least for 12 days
• Use
– To dilate the pupil

17. • MOA
– Relaxation of ciliary muscle causes paralysis of
accomodation (cycloplegia) , near vision is
impaired.
• Onset and duration
– Takes a few hours to occur
– Lasts for two days

18. • MOA
– Tear flow is reduced because
– Parasympathetic activation increases flow.
– Parasympatholytic action will decrease flow.
– But no change in lysozyme and tear protein.
– Therefore, concentrated tear will result.

19. • MOA
– According to “Atropine melanin binding theory”
– Pupil dilate very slowly and cycloplegia takes
sometime, but
– Duration of both are prolonged in deeply
pigmented eyes.

20. Therapeutic uses of atropine (eye)
1. Iridocyclitis
2. For refraction purposes
3. In hyphaema
4. As a premedication agent

21. • Atropine is the drug of choice in acute iridocyclitis.
– Reduction of pain (by relaxation to inflammed iris and
ciliary body)
– Relief of posterior synechiae (most sight threatening
complication in acute condition)
– Atropine stabilizes the blood eye barrier and reduces the
abnormal vascular permeabilities.

22. • Iridocyclitis is a term used to denote inflammation in two parts ofthe
uveal tract of the eye; the iris and the ciliary body.
• It derives its name from combining iritis (inflammation of the iris)
and cyclitis (inflammation of the ciliary body).
• Iridocyclitis may also be referred to asanterior uveitis, or a form
of intermediate uveitis, depending upon the classification
systememployed by the physician.
• Chronic, nongranulomatous Iridocyclitis is an important complication
of juvenile rheumatoid arthritis.

23. • A synechia is an eye condition where the iris adheres to
either the cornea (i.e. anterior synechia)
or lens (i.e. posterior synechia).
• Synechiae can be caused by
ocular trauma, iritis or iridocyclitis and may lead to
certain types of glaucoma.
• Anterior synechia causes closed angle glaucoma, which
means that the iris closes the drainage way of aqueous
humour which in turn raises the intraocular pressure.
• Posterior synechia also cause glaucoma, but with a
different mechanism.
– In posterior synechia, the iris adheres to the lens, blocking
the flow of aqueous humor from the posterior chamber to
the anterior chamber. This blocked drainage raises the
intraocular pressure.

24. • Atropine refraction is necessary in children
especially in squint cases.

25. • For better view of inner eye
– Hyphaema is blood in the front (anterior) chamber
of the eye. It may appear as a reddish tinge, or it
may appear as a small pool of blood at the bottom
of the iris or in the cornea.

26. • 0.4 mg IM atropine as a premed agent
• Usually prevents oculocardiac reflex (occurs due to
vagal stimulation during strabimus surgery) can also
occur in ptosis or entropion surgery
– Slow HR, hypertension, nausea, fainting attack

28. • Inhibition of secretions
– Salivary, lacrimal, bronchial and swear gland secretions
– Resulting dry mouth & skin
– Gastric secretion is only slightly inhibited.
• use
– As a component of pre anaesthetic medication

29. • Heart
– Tachycardia due to blockade of cardiac M receptors
– Modest tachycardia because it has no effect on
sympathetic system only inhibition of preexisting
parasympathetic tone.
• Use
– Treatment of sinus bradycardia (Atropine)

30. • GIT
– GI motility is inhibited by atropine
– Atropine can be used in pathological conditions in which
there is increased GI motility.
– Decrease gastric secretion
• Use
– To facilitate GI endoscopy
– As antispasmodic
– To treat peptic ulcer (not popular now a days)

31. • Other smooth muscles
– Bronchial, biliary and urinary tract smooth muscles are
relaxed by atropine.
– Reflex bronchoconstriction (during anaesthesia) can be
prevented by atropine.
• Use
– Bronchial asthma and some chronic obstructive airway
diseases
– As a component of preanaesthetic medication
– Use in Urinay tract infections (to decrease spasm of
urinary bladder smooth muscle)

32. • CNS
– Mainly excitatory, (restlessness to agitation,
disorientation)
– In atropine poisoning, excitement, irritability,
hyperactivity, rise in body temperature (worsen by loss
of sweating).
– Opposed by physostigmine (specific antidote)

33. • Dry mouth
• Difficulty in talking
• Fever
• Allergic rash
• Blurring of vision
• Excitement
• Cardiovascular collapse
• Convulsion
• Glaucoma (may precipitate acute glaucoma in anatomically narrow angle
individuals)
• Atropine hypersensivity

34. Toxicity

36. Toxicity
• Lethal dose in children is 10-20 mg /adults 80-130 mg
• Single vial of 1% atropine can kill many children
• It should be kept beyond the reach of children.

37. • Gastric lavage (activated charcoal)
• Dark comfortable room
• Ice bags/cold sponging/antifebrile agents
• Specific antidote (physostigmine)
• Supportive measures
– Fluid transfusion, artificial respiration, diazepam,

39. • Natural alkaloid
– Obtained for hyoscyamus niger
• Onset and DOA
– Time taken for full mydriasis – 20 minutes of
instillation
– Then decrease rapidly
– Total passes off after 8 days
– Time taken for cycloplegia is about 40 minutes
(after instillation)
• Preparations
– Available in 0.1-0.5% solution

40. • Use
– Mydriatic for eye examination
• Side effects
– are more or less similar to atropine but
– Psychotic effect is more common in this case.
– In contrast to atropine, scopalamine is CNS depressant.

42. • 10 times less potent than atropine
• Principal mydriatic at one time
• Use
– for refraction purpose in adults
• Onset and DOA
– Mydriasis – commences – 10-20 min , maximal in 30-40
min,
– At 30 min- both light and accomodative reflex are lost ,
an examination may be carried out
– Recovery takes the same time as cyclopentolate if a
miotic is not used but it can be as prolonged as 3 days

43. • Preparations
– 1% and 2% eye drops are commonly used
– 0.25-0.5% - these preparations are not available
commercially
– The higher strength produces slightly larger pupil, with a
more marked effect on the ciliary muscle in reducing
accomodation.

45. • Synthetic
• Very potent mydriatic and cycloplegic
• Same mydriasis but more cycloplegia than
homatropine

46. • Preparations
– Mydriatic concentration – 0.1%
– Cycloplegic concentration – 0.5%-1%
– 0.1% is not available nowadays
– Therefore, if cyclopentolate is used as a mydriatic, then
significant cycloplegia with accompany
• Onset and DOA
– Mydriasis – commences – 10 min, maximal – 30 min,
effect – last to 24 hr

47. • Precautions
– Best avoided in patient with history of uveitis as it has
chemotactic effect on leucocytes.
– May increase IOP (both open and closed angle closure
glaucoma)
– Avoided in children (may produce a peculiar type of
psychotic reaction)
– May produce topical reactions.
• Uses
– Is used for refraction purposes,
– in milder cases of anterior uveitis.
– Cyclopentolate 1% - sometimes used for pre-
operatively to produce maximal mydriasis

49. • Antimuscarinic mydriatic of choice today.
• Depth of mydriasis is adequate for most examinations
because pupil light reflex is depressed.
• Preparations
– Available as 0.5%-1% solution
– Weaker – mydriasis
– Stronger – cycloplegia

50. • Onset and DOA
– Most rapidly acting mydriatic 20-40 minutes
– (cycloplegic action unpredictable)
– DOA 3-6 hours
– Quick onset and short DOA
• Use mainly for
– Purpose of refraction in adults and
– Facilitating the ophthalmoscopy and retinal photography
(along with phenylepherine).

51. • Administration
– If necessary, 2nd drop can be applied after 5 minutes after the
first.
– The mydriasis caused by tropicamide can be reversed, if
necessary, with weak solutions of physostigmine.
• Untoward effects
– Rare side effects.
– May cause transient rise of IOP in close angle glaucoma
patients.
– Rarely, may induce – psychotic reactions and circulatory
collapse
– Initial stinging, allergic and adverse systemic reactions
reported
– If the patient is taking any systemic antimuscarinic drug, the
effect of tropicamide might be augmented.

52. • What are antimuscarnic agents and why they are
named as?
• What is the classification?
• What are the actions of those agents on eye?
• What are the important pharmacology (MOA, PA,
uses, precaution, preparations) of each individual
agents on eye and important untoward effects?

53. Name Strength Onset DOA Residual
accomodation
Atropine 1.0% 36 hr Upto 7 days Nil
Cyclopentolate 0.5% 60 min 24 hr 1 D
Homatropine 1.0% 90 min 24 hr 1 D
Tropicamide 1.0% 30 min 6 hr 2 D

54. Name Strength MOA Onset Duration
of
mydriasis
Reversed
by
Adverse
reactions
Notes
Atropine 1.0% Antimusc
arinic
40 min 7 days Ecothioph
ate
Allergy
Toxicity
Too
strong for
routine
use
Homatrop
ine
1.0%
2.0%
Antimusc
arinic
40 min 48 hr Physostig
mine
Same as
atropine
Rarely
used
Cyclopent
olate
0.5%
1.0%
Antimusc
arinic
30 min 24 hr Physostig
mine
CNS
effects
No longer
available
Tropicami
de
0.5%
1.0%
Antimusc
arinic
15 min 8-9 hr Physostig
mine
Some CNS
effects
Mydriatic
of choice
Phenylep
herine

55. • With any topically applied ophthalmic drug, there is a possiblity of producing an undesirable
effect, either on the eye or on the body as a whole.
• So many of the problems can be avoided by carrying out the following precautions:
– Explain – the reasons – patients & family
– Forewarn – for photophobia – (sunglasses, broad-brimmed hat) – avoid
motorcycle or car driving
– Previous use of mydriatics and any history of allergy
– Any medications currently taking – OTC or POM
– In general – use single drop (might be more in elderly and darkly pigmented
eyes)
– Measure IOP before and after
– Warn for any adverse effects and what action to be taken in such a case..

56. • Hopkins, G, Pearson, R (2007). Ophthalmic Drugs
Diagnostic and Therapeutic Uses. 5th ed. USA:
Elsevier . 85-278.
• Sengupta, KK, Mukherji, R (2006). Essentials of
Ocular Pharmacology and Therapeutics . UK:
Anshan Limited. 148-174.

57. • http://www.austincc.edu/apreview/PhysText/
PNSafferentpt2.html
• http://www.uveitis.org/patients/education/gl
ossary/g-l#IRIDOCYCLITIS
• http://en.wikipedia.org/wiki/Synechia_(eye)
• http://en.wikipedia.org/wiki/Hyphema