Oral Medicine - Pharmacology Flashcards
What are the 5 classes of antibiotics?
Beta-lactams
Macrolides
Lincosamides
tetracycline
nitroimidazole
Mechanism of action of beta lactams
Inhibit cell wall synthesis
Which bacterial enzyme facilitates antibiotic resistance to beta-lactams?
Beta lactamase
What is the name of a beta lactamase inhibitor?
Clavulanic Acid
What is the dosage for amoxycillin + clavulanic acid?
500mg +250mg 8 hourly for 5 days
What type of bacteria are beta lactams active against?
Broad spectrum gram positive and negative bacteria
What is the mechanism of action of macrolide antibiotics?
inhibits protein synthesis
List 3 macrolide antibiotics
erythromyxin, roxithromyxin, clarithromycin
What is a possible side effect of macrolide antibiotics?
Increase risk of cardiac arrhythmias due to QT prolongation
QT is the time for ventricular repolarisation. Elongation = tachycardia
What is a problem with the use of macrolide antibiotics in the dental setting?
There is little activity against periodontal pathogens and declining activity against strep sp.
What is an example of a lincosamide antibiotic?
Clindamycin
When are lincosamides used?
If ptn is non-responsive to amoxycillin + clavulanic acid
What is the dosage for clindamycin?
150mg 4/day
Why are tetracyclines the first line of treatment for periodontal infections?
Active against periodontal pathogens
increased bioavailability in the gingival sulcus
2
What are the side effects of tetracycline?
Staining - dental, oral , skin
hypersensitivity to sun
What is an example of a nitroimidazole antibiotic?
Metronidazole
What is a common dental use for metronidazole?
ANUG
Pericorinitis
adjunct to amoxycillin for spreading infection
What is the dosage for metronidazole?
200mg 3/day for 3 days
severe: 400mg 2/day for 5 days
What is the mechanism of action of metronidazole?
Pro-drug - when metabolised by anaerobic bacteria it becomes bacterocidal
What is the interaction between metronidazole and warfarin?
Metronidazole delays the metabolism of warfarin and therefore should be avoided in ptn on warfarin
What is the mechanism of action of chlorhexidine?
Bacterostatic (0.02%-0.06%)
Bacterocidal (>0.12%)
What is chlorhexidine active against?
gram positive bacteria, fungi, some viruses (HIV, HSV, CMV, Influeza)
What are the risks of chlorhexidine?
Brown discolouration of teeth and tongue
temporary taste alteration
mucosal burn in high concentration
allergic reraction
What is the protocol for chlorhexidine mouthwash?
0.12-0.2% 15ml for 30 sec 2/day
What does the addition of povidone to iodine achieve?
Organic carrier that controls the release of iodine
What is povidone iodine active against?
Perio pathogens, mycobacteria, virus, protozoa
i.e bacteria, fungus, virus
Which antiseptic agent shouldn’t be used if ptn has a history of thyroid dysfunction?
Povidone Iodine
What is the difference between hyposalivation and xerostomia?
Hyposalivation = objective measurement
Xerostomia = subjective feeling
What conditions can contribute to xerostomia? (5)
Sjogrens
Head and neck radiation
Type II diabetes
mental health and stress
medications
What are non-pharmacological options for treatment of xerostomia?
increased water intake
xylitol gum
decreased caffeine
decreased alcohol
natural lubricants e.g olive oil
What is a commercial oral lubricant?
carboxymethylcellulose
what is added to commercial lubricants to increase effectiveness?
Antimicrobials:
lactoferin
lysozyme (in natural saliva)
lactoperoxidase (biotene)
What is a sialogogue?
an agent promoting secretion of saliva
What is a non-pharmocological sialogogue?
Chewing gum
What is a topical pharmacological sialogogue?
1% Malic acid
What is an example of a systemic sialogogue?
Pilocarpine
What is the dosage of pilocarpine?
5mg 3/day for atleast 3 months
What are the risks of pilocarpine?
GI upset
blurred vision
stimulation of other exocrine glands e.g lacrimal
What are underlying risk factors for oral candidiasis?
Diabetes
Anaemia
HIV
Immunosuppression or deficiency
cancer
Denture wearers (poor hygiene)
What is the most important factor in managing oral candidosis?
manage underlying risk factor
What are the 3 groups of antifungals?
Polyenes
Ergosterol Biosynthesis inhibitors
Newer agents
2
Example of polyene antifungals?
Nystatin
Amphotericin B
Example of ergosterol biosynthesis inhibitors
“azole”
miconazole
clotrimazole
itraconazole
fluconazole
Which antifungal should be avoided in diabetes and why?
Nystatin
contains sucrose
Why shouldn’t clotrimazole be taken systemically?
GI and neurolgical side effects
A ptn on warfarin shouldn’t take this class of antifungal. Why?
Ergosterol Biosynthesis inhibitors
“azole”
decreases metabolism of warfarin = increased effect of warfarin = risk of bleeding
What is the protocol for miconazole in the treatment of oral candidiasis?
Gel 2% 2.5ml 3/day for 7-14 days and 7 days after symptoms resolve
What is the protocol for nystatin in the treatment of oral candidiasis?
100,000units/ml 1ml 4/day for 7-14 days, 2-3 days after symptoms resolve
What are the 3 aims of antiviral medications?
- block viral replication
- shorten duration of symptoms
- accelerate healing of lesions
Which HSV virus type is herpes labialis associated with?
HSV1
What are the 3 drug classes of antivirals?
- Acyclic Guanosine Anologues “clovir”
- Acyclic Neucleotide Analogues “fovir”
- pyrophosphate anologue “forscanet”
Which virus type is acyclovir active against?
Herpes virus
Why does acyclovir required early administration to be effective?
Targets viral replication which occurs in the first 48hours of infection. After this viral replication decreases so medication is less effective.
What is the use of forscarnet?
CMV or acyclovir resistance HSV in immunocompromised patients
What are glucocorticoids?
Synthetic anologue of cortisol hormone produced by adrenal glands.
When is the peak production of natural cortisol? How does this affect dosage/prescription?
Morning
Ptn should take corticoids in morning for maximal effect
How much cortisol does the body naturally produce?
20-30mg
What are the side effects of glucocorticoids?
Weight gain
osteoporosis
increased blood glucose
List 5 common glucocorticoids?
Betamethasone
Dexamethasone
Methylprednisolone
Prednisolone
Deflazacort
What are the symptoms of corticosteroid withdrawl syndrome?
Arthralgia
myalgia
mood changes and fatigue
headache
GI problems
What is a method for increasing the contact time of topical corticosteroids with the oral mucosa?
Use in conjunction with an adhesive gel e.g orabase
what are the instructions given to patients for topical corticosteroids?
contact time = 4-30 min 2-3/day (depends on type)
avoid talking, eating, drinking rinsing during this time
What are 3 types of corticosteroid based mouthwashes?
Klobetasol proprionate
dexamethasone proprionate
betamethason proprionate
What is the benefit of intralesion corticosteroid injections?
decreased side effect
increased concentration of corticosteroid at injection site
Describe what corticosteroid sparing is
prescription of immunosuppresive or anti-inflammatory agnets to decrease the ptn’s cumulative exposure to systemic corticosteroids
