The judicious use of antibiotics and analgesics is an integral part of dental practice. While these agents generally are considered safe in the dental setting, their use can result in interactions that can lead to serious morbidity in dental patients.
It is almost certain that the general dental practitioner will encounter patients taking medications that could potentially interact with the drugs prescribed in dental practice. Therefore ensuring that patients' medical histories are up to date will help practitioners avoid potentially serious adverse drug interactions.
What is drug interaction?
A drug interaction may be defined as a situation when a substance, which in this case is another prescribed drug, affects the activity of a drug already taken by a patient.
Once ingested, a drug interaction can occur at any point along the pathway of the drug through the body, from absorption to elimination. Knowing the type of drug interaction can assist in predicting, detecting and avoiding them.
Practical examples of drug interactions in dentistry:
- Specific drugs, such as ketoconazole (an antifungal agent), can only be absorbed in acidic conditions. Therefore any drugs that modify the gastric pH, such as antacids (eg calcium carbonate), proton-pump inhibitors (eg omeprazole) or H2-receptor blockers (eg ranitidine), subsequently reduce the absorption of ketoconazole.
- Rifampicin, which induces CYP450, and leads to increased metabolism of the oral contraceptive pill leading to its failure.
- Aspirin and other NSAIDs inhibit secretion of methotrexate into the urine. This could potentially lead to harmful methotrexate toxicity.
- Antihypertensive agents are local anaesthetics-typically lidocaine with adrenaline can cause potentially dangerous increase in heart rate, with associated peripheral vasoconstriction, leading to an increased blood pressure with potentially harmful consequences.
- NSAIDs interact with diuretics in three different ways: they can cause nephrotoxicity, antagonize the diuretic effect and increase the risk of hyperkalaemia.
- All antihypertensive medications are potentiated by general anaesthesia agents,which could lead to potentially dangerous hypotension.
- There is a ten-fold increase in the risk of myopathy when statins are taken with erythromycin and miconazole.
- NSAIDs (especially diclofenac and ibuprofen) can antagonise the antiplatelet effect of aspirin.
- There have been several reports of significant bleeding in patients taking warfarin with concomitant use of metronidazole.
Tips for avoiding harmful drug interactions:
- Patients' medical and drug histories should be frequently reviewed
- Enquiry about any change in drug plan at every visit if possible.
- Use of alternative drugs where certain medications are contra-indicated.
- When in doubt, talk with the General medical practisioner of the patient and prescribe any drug only after his consent.
- Update yourself with any new developments in the pharmacological aspects of dentistry.
- To reduce the risk of increase in heart rate during administration of Local Anesthesia,use infiltration injections where possible, ensure aspiration is undertaken when administering nerve blocks and keep dosages of lidocaine (with adrenaline) to an absolute minimum.
Thus, utmost care while prescribing any medication is important not only to avoid harm to patients but also to avoid unwanted medico–legal proceedings.
Reference:
- Seymour R A . Dentistry and the medically compromised patient. Surgeon 2003; 4: 207–214
- Seymour R A . Drug interactions in dentistry. Dent Update 2009; 36: 458–470.
- Crispian S . Medical problems in dentistry. 6th ed. London: Churchill Livingstone; 2010.
- Haas D A . Adverse drug interactions in dental practice: interactions associated with analgesics, Part III in a series. J Am Dent Assoc 1999; 130: 397–407.
A practical dental prescribing safety check
Interaction risk is determined by the whole patient context: prescription medicines, over-the-counter products, supplements, allergies, pregnancy status, renal and hepatic function, age, frailty and the proposed dental drug. A current medication list and indication for each medicine should be reviewed before prescribing.
High-priority interaction domains
- Anticoagulants and antiplatelets: balance bleeding risk against the thrombotic risk of interruption; do not advise cessation without coordination with the prescriber.
- NSAIDs: consider gastrointestinal, renal, cardiovascular and bleeding risks, especially with anticoagulants, corticosteroids or other NSAIDs.
- Macrolides, azole antifungals and metronidazole: check for metabolism-based interactions and clinically important effects on medicines such as anticoagulants.
- Central nervous system depressants: avoid unintended additive sedation with opioids, benzodiazepines, alcohol or sedating antihistamines.
- Vasoconstrictors: use careful aspiration, dose control and medical-risk assessment when sympathomimetic effects are relevant.
Documented decision process
Record the indication, selected medicine, dose, duration, interaction check, counselling and any physician consultation. For unfamiliar combinations or medically complex patients, use a current interaction resource or pharmacist review rather than relying on memory.
Continue to drugs used in dentistry and antibiotic prophylaxis before dental treatment.
Frequently asked questions
Is a short dental prescription automatically free of interaction risk?
No. Serious interactions can occur even during short courses when patient medicines, organ function or contraindications are overlooked.
Should anticoagulants be stopped before dental treatment?
Not routinely. Many dental procedures can be managed with local haemostatic measures, and interruption may increase thrombotic risk; coordinate any change with the prescribing clinician.
Why should over-the-counter medicines be recorded?
They can duplicate analgesics, increase bleeding or sedation risk and interact with prescribed medicines.
When should a pharmacist or physician be consulted?
Consult when the interaction is uncertain, the patient is medically complex, organ function is impaired or medication interruption is being considered.
What is the simplest way to reduce prescribing errors?
Use a consistent medication-reconciliation and interaction-check workflow for every prescription.