Local reaction to drugChemical burns the best known example is that of aspirin tablet held against the mucosa close to an aching tooth ‘it will cause superfacial necrosis and a white patch ,dead epithelium is shed and the mucosa heals.Other irritant chemicals are acid etchants or phenol dropped on the mucosa.
Interferance with the oral flora: super infection:prolonged topical use of antibiotic in the mouth kills off sensitive organisms and allow resistant ones, particularly candida albicans, to proliferate, causing thrush in susceptable patients. Use of a topical antibiotic may precipitate candidal infection within 48hrs.
SYSTEMICALLY MEDIATED REACTIONS1-DEPRESSION OF MARROW FUNCTION :
A - few drugs significally depress red cell production alone, though any drug which cause anemia might give rise to oral signs.
the main example is prolonged use of phenytoin (for epilepsy) which in susceptible patients, can cause folate deficiency and macrocytic anemia.
This inturn can cause severe aphthous stomatitis, response promotly follows administration of foliate, and the blood picture returns to normal
B- white cell production depressions:white cell production is depressed by a variety of drugs. Leucopenia may be severe enough to produce the clinical picture of agranulocytosis, with necrotising ulceration of the gingivae and throat which can go on to a severe prostrating illness and septicaemia if untreated,
Drugs which may have this effect include:-
antibacterial. particularly co-trimoxazole. Chloramphenicol
When the main effect is on granulocytes, low-grad oral pathogens, particularly of the gingival margins, are able to overcome local resistance and produce necrotising ulceration.
C- Other drugs may affect haemostasis and cause oral purpura.Drug-induced purpura is often also an early sign of aplastic anaemia caused by drugs such as chloramphenicol. which depress marrow function.
Purpura can produce severe spontaneous gingival bleeding or blood blisters and widespread submucosal ecchymoses.
D- Depression of cell-medical immunity.lmmunosuppression by drugs as such corticosteroids is induced in patients having organ transplants or with immunologically-mediated diseases.
Viral and fungal infections of the mouth are common in immunosuppressed patients and can be severe.
Recurrences of childhood viral infections such as measles and chickenpox are also possible.
E- Lichenoid reactions.Several drugs:-
gold and antimalarials (both used in the treatment of rheumatoid arthritis or other collagen diseases),
the antihypertensive agent methyldopa can cause disease indistinguishable from lichen planus, both clinically and histologically. The mechanism of such reactions is unknown.
F- ACUTE ERYTHEMA MULTIFOME:as discussed earlier,
or other drugs are occasionally implicated, but the mechanisms are unknown and more frequently there is no evidence of a drug reaction.
G- TOXIC EPIDERMAL NECROLYSIS:this, which probably represents the extreme end of the spectrum of the erythema multiforme,
It is one of the most dangerous and severe types of drug reaction.
mucosal involvement is common and cause widespread erosions due to epithelial destructions.
Oral ulceration may precede the dermal changes, and cause the patient to seek treatment for the extreme sorness of the mouth.
Early diagnosis and treatment is important as the reaction can be lethal.
Example :-Metals such as gold salts are important causes but phenylbutazone ,barbiturates and other drugs have also been implicated.
Healing of oral lesions may leave a pattern of lichen planus.
H- FIXED DRUG ERUPTIONS:these consist of sharply circumscribed skin recurring in the same site or sites each time the drug is given.
many drugs are capable of causing this reaction :-
but phenolphthaline , awidly use component of purgatives,is one of the more causes .
Involvement of the oral mucous memberane has been described but is exceedingly rare.
OTHER DRUG EFFECTS1- GINGIVAL HYPER PLASIA:
can cause fibrous hyperplasia . Particularly concentrated at the inter dental papillae
2- ORAL PIGMENTATION:heavy metals such as mercury,bismuth,and lead can cause black or brown deposite in the gingival sulcus by interaction with bacterial productes to form sulphides.
The blue lead line may be particularly sharply defined and indicate the level of the floor of the pocket.
These effects are rarly seen now that mercry and bismuth are no longer used in medicine and lead is no longer a major industrial hazard .
How ever , cisplatine, a cytotoxic drug, can cause a blue line.
Topical antibiotic & antiseptic may cause dark pigmentaion. Particularly of the dorsum of the tongue, due to over growth of the pigment forming bacteria
3- DRY MOUTH:is a relatively common side effect of drugs, particularly those with an atropine like action, such as the tricyclic anti depressants which are widely used.
MANAGEMENT CONSIDERATIONS:oral reactions to drugs are not overall common, nevertheless they may be important as an early sign of a dangerous or lethal reaction.
However , a drug being taken by a patient is not necessarily the cause of any oral symptoms.
Coincidence is often difficult to exclude, particularly with common oral disease such as lichen planus.
The problem is made more difficult by multiple drug treatment. However it is essential to get a detailed history of drug treatment as this may affect other aspects of dental treatment.
Composition of emergency dental kitAromatic spirits of ammonia
Atropine Sulfate 0.5mg Sc or I.V
Diphenhydramine (Antistine)25-50 mg
Epinephrine (Adrenaline) 0.5 ml of 1:1000
Glucogon I.M ,I.V,S.c 1mg
Hydrocortisone sodium succinate 100 mg I.V I.M
Nitroglycerine 0.6 mg sub lingual