28. Oral Medications for Treating the Anterior Eye

Question 1

What are the best practices for prescribing medication? (4 points)

Answer 1

• Select the best drug according to px presentation e.g. where in the eye?
• Ensure max efficacy and least propensity for side effects
• Orals for ocular surrounding tissues
• Use Australian Medicine Handbook as reference

Question 2

What are the 8 patient factors that need to be considered before prescribing?

Answer 2

• Px age
• Weight
• General health status
• Mental status & potential medications using for mental status
• Allergy Hx
• Liver and kidney function
• Present medications
• Pregnancy status / Use of oral contraceptive pills

Question 3

What are the age ranges for neonates, infants and children, according to the Australian Medicine Handbook?

Answer 3

• Neonate = 0 - 28 days
• Infant = 1 month - 2 years
• Child = 2 - 12 years

Question 4

According to AMH, children over the age of ... are eligible for the same dosage as .... Younger px should be assessed for their .... and ... using one of the many ..., such as AMH, MIMs or .... It is also essential that optoms ... with the child’s ... or ....

Answer 4

According to AMH, children over the age of 12 are eligible for the same dosage as adults. Younger px should be assessed for their suitability and contraindications using one of the many reference guides to medicines, such as AMH, MIMs or Australian Prescriber. It is also essential that optoms communicate with the child’s paediatrician or family GP.

Question 5

What are the 5 main classes of oral medications for ophthalmic diseases?

Answer 5

• Antibiotics
• Steroids/ Corticosteroids
• Antivirals
• Analgesics
• Carbonic anhydride inhibitors

Question 6

What are the 5 classes of antibiotics?

Answer 6

• Penicillin
• Cephalosporin
• Macrolides
• Fluoroquinuolones
• Tetracycline

Question 7

Penicillins are ... used in eyecare. They work by inhibiting .... Penicillins contain a ... that allows them to be .... However, ... produce ... which degrades the clinical efficacy of penicillins. In this case, ...and ... can be used.
* ... [dicloxsig] is resistant to ..... It also has a short half life, therefore dosage of ...mg regimen can be taken without regard to ....
* ... [augmentin] is a classic ... penicillin. It is combined with a ... inhibitor, .... This combination increases the drug’s spectrum of activity against .... This extends coverage of ... and .... It also has excellent choice in combating most common ... and ... infections.

Answer 7

• Penicillins are rarely used in eyecare. They work by inhibiting bacterial cell wall synthesis. Penicillins contain a beta-lactam ring that allows them to be bactericidal. However, staphyloccal species produce penicillinase which degrades the clinical efficacy of penicillins. In this case, dicloxacillin and amoxycillin can be used.
• Dicloxacillin [dicloxsig] is resistant to penicillinase. It also has a short half life, therefore dosage of 250mg QID can be taken without regard to meals.
• Amoxycillin [augmentin] is a classic synthetic penicillin. It is combined with a beta lactamase inhibitor, potassium clavulanate. This combination increases the drug’s spectrum of activity against beta lactamase producing bacteria. This extends coverage of G+ and G-. It also has excellent choice in combating most common eye and eyelid infections.

Question 8

What are the 3 levels of penicillin dosage determined by severity of clinical conditions?

Answer 8

BID for 1 week
* Mild - 500mg
* Moderate - 875mg → most common dosage
* Severe - 1000mg

Question 9

What are the potential side effects of penicillins? (3 points)

Answer 9

*Hypersensitivity reactions (20%) → Skin rashes (mostly), severe anaphylaxis (uncommon)
* Alter normal flora in respiratory tract
* GIT upset

Question 10

What are the 3 alternatives to penicillin when one has an allergy to penicillin?

Answer 10

• Cephalosporin
• Macrolide
• Fluoroquinolone

Question 11

Cephalosporins are an alternative to .... The oral type used in optometry is ..., which is commonly traded as .... It is also usually the ... in ophthalmic antibiotics. It affects bacterial .... It contains a ... group, however it is not affected by ... like penicillins as this is derived from .... Depending on the severity or conditions, cephalosporin is usually prescribed for duration with dosage of ... mg regimen or ... mg regimen (2g).
Cephalosporins can destroy ... necessary for the synthesis of ..., which can result in ..., therefore it is contraindicated in ....
Common adverse reactions to cephalosporin are similar to penicillin because ..., where 5-10% of those allergic to penicillin are also .... Consequently, px with hx of penicillin anaphylaxis should avoid the use of cephalosporin and choose either ... or ....

Answer 11

Cephalosporins are an alternative to penicillins. The oral type used in optometry is cephalexin, which is commonly traded as keflex. It is also usually the first choice in ophthalmic antibiotics. It affects bacterial cell wall synthesis. It contains a beta lactam group, however it is not affected by penicillinase like penicillins as this is derived from different amino acids. Depending on the severity or conditions, cephalosporin is usually prescribed for 1 week with dosage of 500mg BID or 500mg QID (2g). Cephalosporins can destroy intestinal bacteria necessary for the synthesis of vitamin K, which can result in impaired blood clotting, therefore it is contraindicated in haemophiliacs. Common adverse reactions to cephalosporin are similar to penicillin because they share similar structures, where 5-10% of those allergic to penicillin are also allergic to cephalosporin. Consequently, px with hx of penicillin anaphylaxis should avoid the use of cephalosporin and choose either macrolide or fluoroquinolone.

Question 12

Fluoroquinolone is a ... that is usually reserved for use when there is a .... Fluoroquinolones inhibit ... by blocking ... activity. Examples include drug which is used by GPs for UTI and drug dosagemg regimen for duration. This is contraindicated in epilepsy, ... and ....

Answer 12

Fluoroquinolone is a broad spectrum antibiotic that is usually reserved for use when there is a penicillin allergy. Fluoroquinolones inhibit bacterial DNA synthesis by blocking DNA gyrase activity. Examples include norfloxacin which is used by GPs for UTI and ciprofloxacin 500mg QID for 1 week. This is contraindicated in epilepsy, myasthenia gravis and pregnancy.

Question 13

How can you differentiate between hordeolum internum, chalazion and pre-septal cellulitlis based on px response?

Answer 13

• Hordeolum internum - pain at the middle of the eyelid
• Chalazion - no pain
• Preseptal cellulitis - pain all over the orbit

Question 14

Internal hordeolum is an ..., ... infection that affects the ... and caused by ....
It is managed by ... and ....
There are 3 different treatment options, all are for a treatment period of ... days:
* Most common = trade name ...mg regimen
* Augmentin ...mg regimen
* Dicloxacillin ...mg regimen

Answer 14

Internal hordeolum is an acute, focal infection that affects the meibomian glands and caused by staphylococcus aureus.
It is managed by hot compresses and topical therapy.
There are 3 different treatment options, all are for a treatment period of 7 days:
* Most common = Keflex 500mg QID
* Augmentin 875mg BID
* Dicloxacillin 250mg QID

Question 15

Preseptal cellulitis can develop from .... It is characterised by the ... of the eyelid, anterior to the .... This should be differentially diagnosed from ..., which is a more ... condition. To differentiate, ... should be conducted. If there is no pain, this indicates .... This is different to internal hordeolum as there is no .../ ....
Preseptal cellulitis is commonly caused by ... in adults and ... in children. It also associates with ..., ... and upper respiratory tract infections. Preseptal cellulitis should be treated ... using either drug ..mg regimen or drug ...mg regimen, usually for 5 to 10 days.

Answer 15

Preseptal cellulitis can develop from internal hordeolum. It is characterised by the diffuse inflammation of the eyelid, anterior to the orbital septum. This should be differentially diagnosed from orbital cellulitis, which is a more severe condition. To differentiate, motility should be conducted. If there is no pain, this indicates preseptal cellulitis. This is different to internal hordeolum as there is no focal lesion/ inflammation. Preseptal cellulitis is commonly caused by staphylococccus spp in adults and streptococcus pneumoniae in children. It also associates with sinusitis, dacryocystitis and upper respiratory tract infections. Preseptal cellulitis should be treated empirically using either augmentin 500mg QID or keflex 500mg QID, usually for 5 to 10 days.

Question 16

Acute dacryocystitis is the ... of the overlying .... It is usually associated with obstruction of the .... This is commonly caused by ... or .... Px may present with ... discharge, ... and pain and swelling over the ... area. Treatment involves drug ...mg regimen for duration days. If intervention is done in a timely matter, there should be a ....

Answer 16

Acute dacryocystitis is the inflammation of the overlying lacrimal sac. It is usually associated with obstruction of the nasolacrimal duct. This is commonly caused by staphylococcus epidermidis or aureus. Px may present with mucopurulent discharge, epiphora and pain and swelling over the medial canthal area. Treatment involves Keflex 500mg QID for 7 days. If intervention is done in a timely matter, there should be a rapid improvement.

Question 17

Macrolides are not usually used as .... They inhibit ... and are mainly ...., unless in high concentrations. Macrolides are commonly used in ... infections (...) and ....
In ..., px should first be prescribed ... for ...-... days and only prescribe macrolides unless no improvement.
There are two main macrolides:
* ... common choice in pregnancy and
* ... great against chlamydial infections.
* They are both active against ... and some .... They are also an alternative when ... are contraindicated.

Answer 17

Macrolides are not used usually as first line antibiotics. They inhibit protein synthesis and are mainly bacteriostatic, unless in high concentrations. Macrolides are commonly used in chlamydial infections (chlamydia trachomatis) and pregnancy.
In pregnancy, px should first be prescribed warm compresses for 2-3 days and only prescribe macrolides unless no improvement.
There are two main macrolides:
* Erythromycin common choice in pregnancy and
* Azithromycin great against chlamydial infections.
* They are both active against G+ and some G-. They are also an alternative when tetracycline are contraindicated.

Question 18

Chlamydia trachomatis is a ... disease that causes ..., recurrent ..., thick ... discharge, ... or ... and keratitis with ... commonly in the periphery. Drug ...g regimen is always the first line treatment. However, if px is not responsive, drug ...mg regimen for ... days or drug ...mg regimen ...-... weeks may be prescribed.

Answer 18

Chlamydia trachomatis is a sexually transmitted disease that causes inclusion conjunctivitis, recurrent red eye, thick ropy discharge, papillae or follicles and keratitis with subepithelial infiltrates commonly in the periphery. Azithromycin 1g single dose is always the first line treatment. However, if px is not responsive, Erythromycin 500mg QID for 7 days or Doxycycline 100mg BID 1-3 weeks may be prescribed.

Question 19

Tetracycline use is limited due to .... ... is the most effective tetracycline in ocular diseases. Tetracyclines have the fewest .... They can decrease the bioactivity of .... Doxycycline has ... properties at low doses. This is because it can inhibit ... and ..., which are damaging enzymes implicated in ..., ... etc. It is useful in dry eye disease due to its ... properties and ability to ..., alter ... and alter .... Doxycycline is therefore also useful in ..., ... and .... Tx with doxycycline often takes ....

Answer 19

Tetracycline use is limited due to antibiotic resistance. Doxycycline is the most effective tetracycline in ocular diseases. Tetracyclines have the fewest potential side effects. They can decrease the bioactivity of major inflammatory cytokines. Doxycycline has anti-inflammatory properties at low doses. This is because it can inhibit MMP-1 and MMP-3, which are damaging enzymes implicated in corneal damage, recurrent erosions etc. It is useful in dry eye disease due to its anti-inflammatory properties and ability to modify and enhance lipid metabolism, alter meibomian gland function and alter tear film. Doxycycline is therefore also useful in meibomian gland dysfunction, ocular rosacea and recurrent corneal erosion. Tx with doxycycline often takes a longer period of time.

Question 20

What are the potential side effects of doxycycline? How can these be eased?

Answer 20

• GI upset → mitigated by drinking lots of water
• Yeast infection
• Photosensitivity → all can be minimised by lowering dosage

Question 21

What are the potential interactions that doxycycline can have with other products?

Answer 21

Doxycycline can become ineffective when taken with diary products or antacids as calcium can chelate doxycycline. Px should be advised to avoid taking doxycyline within 2 hours after dairy products.

Question 22

What are the contraindications for using doxycycline? (3 points)

Answer 22

• Children under the age of 8 → may discolour their teeth or hinder bone improvement
• Pregnant or nursing women → use macrolides instead
• Renal dysfunction

Question 23

How is doxycycline used in meibomain gland dysfunction (2 different rx)? What are the benefits? Which other medication has been shown to give similar effects?

Answer 23

• 50mg BID for 1 month
• 25mg BID for 3-6 months
  Doxycycline enhances fatty acid metabolism within the meibomian glands. It decreases the bioactivity of the major inflammatory cyctokines (MMP-1 and MMP-3)
• Pulsed dose of azithromycin has been found to be equivalent to 6 weeks use of doxycycline, however it is still a new finding

Question 24

What is used for the treatment of recurrent corneal erosion syndrome? (2 different rx; one topical and one oral)

Answer 24

Topical Fluorometholone (FML) 0.1% TID for 4 weeks (4/52) + Oral Doxycycline 50mg BID for 8 weeks

Question 25

Antivirals are all placebo in nature until they are converted by`...` (`process`) into active medicine. Once active, they eradicate `...`. Antiviral do not affect `...`, therefore have excellent safety and practically no `...`. They are most effective when used within the first `...` hours. However, they are contraindicated in `...`. Dosage may be adjusted with `...` and this must be co-managed with px's `...`.

Answer 25

Antivirals are all placebo in nature until they are converted by `virally expressed thymidine kinase` (`phosphorylation`) into active medicine. Once active, they eradicate `viral replication`. Antiviral do not affect `non-virally infected cells`, therefore have excellent safety and practically no `side effects`. They are most effective when used within the first `72` hours. However, they are contraindicated in `renal failure`. Dosage may be adjusted with `renal insufficiency` and this must be co-managed with px's `specialist physician`.

Question 26

What are the 3 types of antivirals used against herpes simplex virus and varicella zoster virus?

Answer 26

* Acyclovir * Valtrex (valacyclovir) * Famvir (famciclovir) - $15 OTC *valtrex and famvir are more commonly used due to less frequent dosage and better absoption and bioavailability "

Question 27

What are the dosages of antivirals used for Herpes zoster virus?

Answer 27

* Acyclovir 800mg 5 times a day for 7-10 days → shorter t1/2 therefore more frequent dosage * Valcyclovir 1000mg TID for 7-10 days * Famciclovir 500mg TID for 7-10 days (Double dosage that of Herpes Simplex)

Question 28

What are the dosages of antivirals used for Herpes simplex virus? When is oral medication used?

Answer 28

HSV is usually managed with topical antivirals. Oral antiviral is only used when px experience toxicitiy or are allergic to the topical agents. This may also be used in px who are immuno-compromised with primary herpatic dermatitis. Dosage is half that of HZV * Acyclovir 400mg 5 times a day for 7-10 days * Valcyclovir 500mg TID for 7-10 days * Famiciclovir 250mg TID for 7-10 days

Question 29

Which antiviral has been found to help reduce recurrent herpes simplex keratitis? What is the dosage?

Answer 29

Acyclovir. 400mg BID used for a year or two

Question 30

Steroids have broad spectrum `...` properties, which usually targets 3 inflammatory pathways: `...`, `...` and `...`.

Answer 30

Steroids have broad spectrum `anti-inflammatory` properties, which usually targets 3 inflammatory pathways: `cytokine production`, `lymphocyte trafficking` and `vascular permeability`.

Question 31

What are steroids use for?

Answer 31

* Allergic blepharodermatitis * Tertiary ophthalmology * Giant cell arteritis * Recalcitrtant uveitis * Eczema * Sinusitis * Asthma * Acute intervertebral disc problems

Question 32

Oral steroids are usually used when `inflammation...` or when `...`. The longer the use of steroids, the `...`.

Answer 32

Oral steroids are usually used when `inflammation did not respond to topical management` or when `the clincally presenting case indicates that topical will be sub-optimal`. The longer the use of steroids, the `longer term side effects will last`.

Question 33

What are the main precautions of steroids? (3)

Answer 33

* Peptic ulcer disease - may need proton inhibitor * Diabetes - may need insulin dosage adjusted * Pregnancy

Question 34

What is the most commonly prescribed oral steroids in ophthalmic use? How is it prescribed?

Answer 34

Prednisolone. Pulse dose for 8 days with meals and taken in the morning, with tapering 50mg for 2 days → 25mg for 2 days → 12.5mg for 2 days → 5mg for 2 days

Question 35

Which analgesics are usually used to control ocular pain?

Answer 35

* Topical cycloplegia * Topcal NSAIDs * Oral NSAIDs are used for px comfort when topical are not sufficient

Question 36

What are the ocular conditions that require the use of analgesics?

Answer 36

* Corneal abrasions * Foreign body * Recurrent erosions * Eyelid infection/ inflammation * Inflammatory keratitis * Painful uveitis

Question 37

What are the common oral analgesics? What may be needed if pain is not managed using these?

Answer 37

* Common OTC analgesics: Paracetamol or Ibuprofen * Req Rx: short term Codeine (can lead to kidney or liver dysfunction)

Question 38

Name the two types of analgesics that contain codeine.

Answer 38

* Panadeine forte = paracetamol 500mg + codeine 30mg * Nurofen plus = ibuprofen 200mg + codeine 12.8mg dose relative to pain, divide 4-6 hours

Question 39

What are carbonic anhydrase inhibitors? Give an example in opthalmological use.

Answer 39

Carbonic anhydrase inhibitors block enzyme carbonic anhydrase, which is a catalyst in production of aqueous humour. An example is oral acetazolamide (Diamox), which is used in acute angle closure to reduce IOP.

Question 40

Outline the protocol for managing acute anterior chamber angle closure. * 1 drop `...` agent e.g. timolol 0.5% * 1 drop alpha agonist e.g. `... ...%` * 1 drop `...` e.g. brinzolamide 1% * 1 drop pilocarpine 2% * if the eye is red and inflamed, instill 1 drop of ` ...` OR Oral dose of acetazolamide 500mg (`Diamox`) → 2 x 250mg tablets

Answer 40

Outline the protocol for managing acute anterior chamber angle closure. * 1 drop `beta blocking` agent e.g. timolol 0.5% * 1 drop alpha agonist e.g. `apraclonidine 0.5%` * 1 drop `carbonic anhydrase inhibitor` e.g. brinzolamide 1% * 1 drop pilocarpine 2% * if the eye is red and inflamed, instill 1 drop of `high penetrance topical steroid` OR Oral dose of acetazolamide 500mg (Diamox) → 2 x 250mg tablets

Question 41

What are the contraindications for using Diamox (acetazolamide)?

Answer 41

Sulphur allergy