Week 7 - Pharmalogical managment of ocular infections Flashcards
Antibacterials:
• Macrolides
- Azithromycin
• Quinolones
- Ofloxacin
• Other
- Chloramphenicol
- Fusidic Acid
Anti protazoal/antibacterial and antivirals:
• Anti protozoal/ Antibacterial
- Propamidine isethionate
• Antivirals
- Aciclovir
- Ganciclovir
What is a antimicrobial agent?
•An antimicrobial is an agent, either natural or synthetic, that kills or inhibits the growth of susceptible microorganisms.
• An antibiotic substance is produced by natural metabolic processes of some microorganisms that can inhibit or kill other microorganisms.
• Antimicrobials may be further classified as antibacterial, antiviral or antiprotozoal, depending on the type of organism against which they exert an effect.
Name 3 types of bacteria’s associated with ocular infections?
• Staphylococcus
• Chlamydia trachomatis
• Pseudomonas aeruginosa
Name 3 types of Viruses associated with ocular infections?
• Adenovirus
• Enterovirus (especially type 30)
• Herpes simplex virus
Name a type of fungi associated with ocular infections?
• Candida species
Name 2 types of protazoa associated with ocular infections?
• Acanthamoeba species
• Naegleria species
Action of antibacterial drugs:
Site of action of antibacterial agents is commonly:
• The cell membrane (or more selectively the cell wall) - allows uptake of nutrients by passive diffusion
• DNA gyrase - essential for bacterial replication
• The ribosomes - the site of protein synthesis
Lids and lid margin: Infection types and associated bacteria:
• Preseptal cellulitis: Staphylococcus, streptococcus, influenza
• Blepharitis: Staphylococcus
Conjunctiva : Infection types and associated bacteria:
• Conjunctivitis (Adult): Staphylococcal, streptococcal, chlamydial
• Conjunctivitis (Neonates and children): Chlamydia, influenza, streptococcal
Globe : Infection types and associated bacteria:
• Endophthalmitis: staphylococcus, streptococcus, Propionibacterium acnes
Orbit : Infection types and associated bacteria:
• Orbital cellulitis: Staphylococcus, streptococcus
• Common in children: Haemaphilus, influenza
Cornea : Infection types and associated bacteria:
• Keratitis: Streptococcal, staphylococcus, pneumoniae
Aminoglycosides: Mechanism, medicinal forms, indications:
Mechanism
• Interfere with ribosome function affecting protein synthesis
- Produce an abnormal codon
• Bacteriocidal
Medicinal Forms
Available topical preparations
• Gentamicin (0.3% Generic) (PoM)
• (Tobramycin)
• Neomycin in combination with steroid products (PoM)
Indications
Bacterial Eye infections
IP OPTOMETRISTS ONLY
Aminoglycosides:
Typically not used as first line treatment for bacterial conjunctivitis or bacterial keratitis as better for gram negative than gram positive bacteria
• Gentamicin (and Tobramycin) used to treat P. Aeruginosa
• Neomycin - broader spectrum but not effective against P. Aeruginosa, currently only available in combination drops with dexamethasome and polymixicin B (Maxitrol)
• Neomycin used in combination with steroids to treat post operative inflammation… However becoming less commonly used for this purpose as now listed as “less suitable for prescribing in the BNF”
Gentamicin: Cautions and Interactions
Cautions
• Nephrotoxicity
• Ototoxicity
• Neuromuscular blocking effects
Interactions
• Concurrent use with other potentially nephrotoxic or ototoxic drugs should be avoided
IP OPTOMETRISTS ONLY
Gentamicin: Contraindications, undesirable effects, pregnancy and breastfeeding
Contraindications
•In cases of a known allergy to aminoglycosides
• Due to neuromuscular blocking effects contraindicated in myasthenia gravis and related conditions
Undesirable effects
• Local sensitivity; blurred vision, eye irritation, burning sensation, stinging sensation, itching
Pregnancy and Breastfeeding
• Usage in pregnancy should only be considered in life-threatening situations where expected benefits outweigh possible risks. The amount of gentamicin ingested from the milk is unlikely to result in significant blood levels in breast-fed infants
Cephalosporins: mechanisms, medicinal forms, indications
Mechanism
• Interferes with Cell wall synthesis
• Bacteriocidal
Medicinal forms
Available for use as intracameral injection
•Cefuroxime (Aprokam intracameral injection) (PoM)
Indications
• Prophylaxis of endophthalmitis after cataract surgery
•Advocated for this purpose by the Scottish Medicines Consortium
Cephalosporins: cautions; interactions; pregnancy and breastfeeding
Cautions
• Combined operations with cataract surgery
• Complicated cataract surgery
• Reduced endothelial cell count
• Severe risk of infection
• Severe thyroid eye disease
Interactions
• More likely to cause nephrotoxicity if combined with other preparations such as aminoglycosides, methotrexate, acyclovir, ganciclovir, ketorolac
Pregnancy and breastfeeding
• Safe to use, present in breastmilk in low concentrations
Macrolides: Mechanism, medicinal forms, indications
Mechanism
• Inhibits translocation during protein synthesis taking place at the ribosomes
• Bacteriostatic
Medicinal Forms
Available topical preparations
• Azithromycin (Azyter 1.5% SDU eye drops) (PoM)
• (Erythromycin)
Indications
• Chlamydia trachomatis treatment
• Bacterial Conjunctivitis
IP OPTOMETRIST ONLY
Macrolides
• Erythromycin most useful against gram positive organisms and a few gram negative organisms (such as N. Gonorrheae)
• Azithromycin commonly used for the treatment of blepharitis by ophthalmologists
• Use in blepharitis is off label
• Other off label uses by ophthalmology:
- Topical erythromycin and systemic penicillin to treat neonatal N. Gonorrhea conjunctivitis
- Systemic erythromycin and topical azithromycin to treat neonatal chlamydial conjunctivitis
Azithromycin: Cautions and interactions
Cautions
Patients should be informed that treatment should cease at the end of the 3 day course even if residual symptoms remain
Interactions
• Many varied interactions, consult the BF, particularly problematic when prescribing systemic erythromycin
IP OPTOMETRISTS ONLY
Azythromycin: contraindications; undesirable effects; pregnancy and breast feeding
Contraindications
Hypersensitivity to azithromycin, to any other macrolide or to the excipient Triglyceride
Undesirable Effects
• Common:
- Eye discomfort
- Blurred vision
• Uncommon:
- Eye allergy
- Angioedema
Pregnancy and Breastfeeding
• Listed as safe for use during pregnancy and breastfeeding
IP OPTOMETRISTS ONLY
Quinolones: Mechanism and indications
Mechanism
• Interferes with DNA gyrase to inhibit protein metabolism
• Bacteriostatic
Indications
• Ciprofloxacin is indicated for superficial bacterial eye infections, severe superficial
eye infections, and corneal ulcers
• The other drugs in this class are indicated for eye infections
IP OPTOMETRISTS ONLY
Quinolones: medical forms
Medicinal Forms
Available topical preparations
• Ciprofloxacin (Ciloxan 0.3% eyedrops) (PoM)
• Levofloxacin (Levofloxacin generic 5mg/ml eyedrops) (PoM)
• Moxifloxacin (Moxivig 0.5% eyedrops) (PoM)
• Ofloxacin (Exocin 0.3% eyedrops) (PoM)
Ofloxacin: Cautions and interactions
Cautions
• Safety and effectiveness in infants below the age of one year have not been established.
•Caution should be taken in patients with known risk factors for prolongation of the
QT interval such as, for example:
- concomitant use of drugs that are known to prolong the QT interval (e.g. Class IA and III anti-arrhythmics, tricyclic antidepressants, macrolides, antipsychotics)
- cardiac disease (e.g. heart failure, myocardial infarction, bradycardia)
- elderly patients and women may be more sensitive to QTc-prolonging medications.
Therefore, caution should be taken when using fluoroquinolones, including EXOCIN®, in these populations.
Interactions
- as per above
IP OPTOMETRISTS
Ofloxacin: contraindications, undesirable effects, pregnancy and breast feedibg
Contraindications
• Contraindicated in those with a known allergy to the drug or the excipients in the formulation
Undesirable Effects
• Eye irritation and ocular discomfort
•Ventricular arrhythmia(reported predominantly in patients with risk factors for QT prolongation)
Pregnancy and Breastfeeding
• Not suitable for use during pregnancy or breastfeeding
IP OPTOMETRIST ONLY
Chloramphenicol: Mechanism, medicinal forms, indications
Mechanism
• Inhibition of protein synthesis by interaction with bacterial ribosomes
• Bacteriostatic
Medicinal Forms
Available topical preparations
• Chloramphenicol generic 0.5% eyedrops (5ml bottle and SDUs) (PoM)
• Chloramphenicol generic 1% eye ointment (PoM)
Indications
•Superficial eye infections
ENTRY LEVEL OPTOMETRISTS
Chloramphenicol: dosages
• 0.5% eyedrops; one drop into the infected eye every two hours for 48 hours. After this period, treatment should be every four hours during waking hours. Eye drops may be supplemented by ointment at night. The course of treatment should last five days (even if symptoms improve).
• 1% eye ointment: put a small amount into the affected eye four times a day for two days, and then twice a day for five days.
Chloramphenicol description:
• Potent broad spectrum (effective against both gram positive and negative)
• Ineffective against pseudomonas aeruginosa
• Widely used due to:
- Broad spectrum
- Good corneal penetration
- Little cross resistance
• Used in management of bacterial conjunctivitis, hordeolum, staphylococcal and seborrheic blepharitis, nasolacrimal duct obstruction where there is evidence of infection, dacryocystitis, marginal keratitis.
• Cost-effective treatment
Chloramphenicol ages and type of med form:
• Can be used age 2 years + when supplied directly by an entry level optometrist, can write a written order as an exempted POM for patients from age 1 month +
• Important to note that chloramphenicol is available as various branded eye drops and eye ointments, which are P meds, e.g. Optrex infected eyes, eye drops 0.5% chloramphenicol
• These preparations are only suitable for treatment of acute bacterial conjunctivitis, and can only be used in patients over age 2 and can only be used for a maximum of 5 days
Chloramphenicol: Cautions and interactions
Cautions
• Risk of aplastic anemia after topical chloramphenicol use is less than one per million treatment courses
Interactions
• Safety for use during pregnancy and breastfeeding has not been established
• Avoid in patients taking drugs liable to depress bone marrow function
Chloramphenicol: contraindications, undesirable effects, pregnancy and breastfeeding
Contraindications
• Hypersensitivity to the drug or any of the excipients
• Known personal or FH of blood dyscrasias, including aplastic anaemia
Undesirable Effects
Transient irritation, burning, stinging, itching and dermatitis
Pregnancy and Breastfeeding
Not recommended during pregnancy or breastfeeding
Fusidic acid: Mechanism, medicinal forms, indications, dose
Mechanism
• Inhibition of protein synthesis by inhibiting DNA translocation
•Bacteriostatic
Medicinal Forms
Available topical preparations
• Fusidic Acid 1% viscous eye drops(exempted PoM)
Indications
• Staphylococcal eye infections
Dose
Apply twice daily, Treatment should be continued for at least 48 hours after the eye returns to normal.
ENTRY LEVEL OPTOMETRIST
Describe fusidic acid:
• Potent narrow spectrum antibiotic, effective against gram positive bacteria, in particular staphylococcus aureus
• Treatment of marginal keratitis, blepharitis, conjunctivitis
• Very expensive currently, since Fusithalmic viscous eye drops are no longer available only product available is fusidic acid cost £29.06 per 5g tube
• As a result has been removed from many local formularies
• Can be used on children of any age
ENTRY LEVEL OPTOMETRIST
Fusidic acid: Cautions and Interactions
Cautions
•Not to be worn with contact lenses
• Contains BAK which can cause eye irritation and contact lens discolouration
Interactions
• Systemic interactions are unlikely since systemic exposure after application of Fusidic acid eye drops is negligible
ENTRY LEVEL OPTOMETRIST
Fusidic acid: contraindications; undesirable effects; pregnancy and breastfeed
Contraindications
• Hypersensitivity to the drug or any excipients
Undesirable Effects
•Common blurred vision, burning, redness and stinging on application
• Uncommon hypersensitivity, eyelid oedema, lacrimation, skin rash, angiodema
Pregnancy and Breastfeeding
• Can be used during pregnancy and breastfeeding
Topical antiprotazoal/antibacterials: Mechanism, indications
Mechanism
• Aromatic diamidine disinfectant with antibacterial, antiprotozoal and antifungal actions
Indications
• It may be used topically for the treatment of minor eye infections such as conjunctivitis and blepharitis.
ENTRY LEVEL OPTOMETRIST
Topical Antiprotazoal/antibacterial: Medicinal forms
Medicinal Forms
Available topical preparations
• Propamidine isethionate 0.1% eye drops (Brolene eye drops) (P)
•Dibrompropamidine 0.15% eye ointment (GoldenEye ointment)(P)
•Propramidine isethionate 0.1% eye drops (GoldenEye drops) (P)
ENTRY LEVEL OPTOMETRIST
Propramidine Isetionate: describe
• Propamidine isetionate is active against Gram-positive non-spore forming organisms, but less active against Gram-negative bacteria and spore forming organisms. It also has antifungal properties.
• It may be used off license in the treatment of acanthamoeba keratitis by specialists only
• Works well even in the presence of copious purulent discharge
Propramidine Isetionate: Cautions and interactions
Cautions
• If no significant improvement after 2 days discontinue and consult a physician
• Unsuitable for use with contact lenses
• If vision is disturbed or becomes worse during the treatment regime discontinue and consult a physician
Interactions
None known
Propramidine Isetionate: Contraindications, undesirable effects; pregnancy and breastfeeding
Contraindications
- Hypersensitivity to the drug or any excipients
Undesirable Effects
- Eye discomfort, blurred vision
Pregnancy and Breastfeeding
- Not suitable during pregnancy or breastfeeding
Viruses:
• Simple noncellular structures
• Contain nucleic acid and a
capsid(protein coat)
• Sometimes an envelope (an
additional glycoprotein coat
around the capsid) and a tail
Action of Antiviral drugs
• Topical antiviral drugs are active against herpes simplex
• Block the ability of the virus to replicate DNA
• Topical antivirals (acyclovir and ganciclovir are prodrugs i.e. once biotransformed inside virus infected corneal and conjunctival cells are active against the virus
• The active drug blocks DNA transcription leading toDNA that is fragmented and no longer functional, as a result herpes simplex fails to replicate
Topical Antiviral: Mechanism; Medicinal forms; indications
** Mechanism**
Block the actions of viral DNA/RNA polymerase enzymes
Medicinal Forms
Available topical preparations
•Aciclovir 3% ophthalmic ointment (Zoviraz) (PoM)
•Gancilovir 0.15% eye ointment (Virgan) (PoM)
Indications
Herpes simplex keratitis
IP OPTOMETRISTS ONLY
Ganciclovir: describe
• Available on PGD’s in some local shared care schemes in Scotland
• Can be used by IP optometrists ( and optometrists using PGD’s) to treat uncomplicated superficial acute or recurrent herpes simplex keratitis
• Aciclovir may be used in children but use of ganciclovir in children is not recommended ( not recommended under age 18)
• Not effective against other viral organisms which can cause conjunctivitis e.
adenovirus
Ganciclover: Cautions, interactions, contraindications
Cautions
• Stinging on instillation
• Avoid wearing contact lenses during treatment regime
• Avoid if known hypersensitivity to acyclovir or valaciclovir
Interactions
• The concomitant administration of Chloramphenicol with other drugs liable to depress bone marrow function should be avoided
Contraindications
• Hypersensitivity to the active drug or to any of the excipients
• Myelosuprresssion during previous exposure to chloramphenicol.
• Known personal or family history of blood dyscrasias including aplastic anaemia
Ganciclover: undesirable effects; pregnancy and breastfeeding
Undesirable Effects
• Very common SP (however, this did not necessitate an early termination of treatment and healed without sequaele).
• Common - transient stinging on instillation, conjunctivitis
• Rare - Blepharitis
• Very rare - Immediate hypersensitivity reactions including angioedema and urticaria.
Pregnancy and Breastfeeding
• Manufacturer advises avoid unless no suitable alternative - limited information available
