|
| A) | It serves as a vasodilator. | ||
| B) | It decreases the systemic absorption of the local anesthetic. | ||
| C) | It increases the duration of the effect of the local anesthetic. | ||
| D) | An accompanying preservative such as sodium bisulfite is needed. |
Lidocaine (2%) was the first amide-based local anesthetic created in the 1940s and remains the most popular local anesthetic used in the United States today [2,3]. The onset of anesthesia is usually less than five minutes, and allergic reactions are a rarity. Lidocaine is available without a vasoconstrictor but is most commonly used with a 1:100,000 concentration of epinephrine. The addition of epinephrine constricts the small blood vessels in the injection area, which decreases the systemic absorption of the local anesthetic and diminishes the potential for systemic toxicity. Decreased vascular perfusion also confines the local anesthetic at the injection site for a longer duration and potentiates the depth and duration of anesthesia [3]. Because epinephrine is a catecholamine and can increase heart rate and blood pressure, its use in cardiac and hypertensive patients should be minimized or, in some circumstances, avoided completely. Lidocaine and all local anesthetics that contain epinephrine also include the preservative sodium bisulfite. This substance is added to delay the oxidation of epinephrine, which would cause its deterioration. Patients with allergies to sulfites may have reactions to this component and should not be administered local anesthetics containing epinephrine and the accompanying preservative [3].
| A) | Lidocaine | ||
| B) | Articaine | ||
| C) | Mepivicane | ||
| D) | Bupivacaine |
Bupivacaine is a very potent local anesthetic available in 0.5% concentration, as opposed to lidocaine, which is generally produced in a 2% concentration [5]. The onset of anesthesia is approximately 10 minutes; however, the duration of soft tissue anesthesia can extend up to 12 hours [5].
| A) | is primarily metabolized in the kidneys. | ||
| B) | has analgesic but not antipyretic properties. | ||
| C) | acts by decreasing prostaglandin synthesis in the central nervous system. | ||
| D) | has more adverse effects on the gastrointestinal system compared to the NSAIDs. |
Acetaminophen was first approved for use by the FDA in 1951, and it is both an analgesic and antipyretic (fever reducer) [20]. It is used in dentistry for the treatment of mild-to-moderate pain and can be dispensed by itself or in combination with narcotic medications such as codeine, hydrocodone, or oxycodone. This analgesic works by decreasing the synthesis of prostaglandins, chemical mediators of inflammation and pain, in the central nervous system and by peripherally blocking the generation of pain impulses. Because the primary metabolism of acetaminophen occurs in the liver, patients with impaired liver function can have difficulty metabolizing this medication properly and can cause further damage to the hepatocytes (liver cells) by ingesting even small doses. The use of alcohol can exacerbate the hepatotoxic potential of acetaminophen, and therefore it should not be consumed concurrently with this medication. Concomitant use of carbamazepine, isoniazid, and rifampin can increase the hepatotoxic potential of acetaminophen [18].
However, acetaminophen does have advantages over some other analgesics. It is better tolerated in some patients, with fewer gastrointestinal side effects compared to nonsteroidal anti-inflammatory drugs (NSAIDs). Acetaminophen is also safe to take with antihypertensive drugs, unlike long-term NSAID use, which decreases the efficacy of these medications.
| A) | increase the clearance of lithium. | ||
| B) | enhance the antiplatelet effect of clopidogrel. | ||
| C) | decrease the anticoagulant effect of warfarin. | ||
| D) | increase the efficacy of ACE inhibitors and beta-blockers. |
Ibuprofen is associated with several drug interactions, some of which can be dangerous. The clearance of lithium, a medication used to treat bipolar disorders, can be reduced by simultaneous use of ibuprofen. The efficacy of medications used to treat hypertension, such as angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, and diuretics (e.g., hydrochlorothiazide), can be decreased by the extended use of ibuprofen. The anticoagulant effects of warfarin and the antiplatelet effects of clopidogrel can be enhanced by the simultaneous use of ibuprofen, with the potential for internal bleeding. Although it is available over-the-counter, ibuprofen is contraindicated in the last trimester of pregnancy as it may cause closure of fetal ductus arteriosus, fetal renal damage, inhibited clotting, and delayed labor and birth [18].
| A) | have sedative effects. | ||
| B) | cause respiratory depression. | ||
| C) | be transmitted through breast milk. | ||
| D) | All of the above |
Codeine is a prototype opioid medication. When used in dentistry, it is most frequently combined with acetaminophen and less frequently with aspirin or ibuprofen. When used in combination with acetaminophen the amount of codeine per tablet can vary from 7.5 mg to 60 mg [18]. This medication is used for mild-to-moderate pain of odontogenic or postprocedural origin. About 10% of codeine is converted to the active metabolite of morphine [23]. The remaining significant metabolites of codeine are codeine-6-glucuronide (70%), norcodeine (10%), and hydromorphone (1%) [18,24]. Codeine's active metabolite of morphine can be transmitted through breast milk in levels great enough to cause potentially fatal respiratory depression in infants [18]. Respiratory depression among opioid medications is dose-related and a potentially serious adverse effect. The respiratory depression and sedative effects of codeine can be enhanced by alcohol or other medications, in some cases resulting in profound sedation. Clinicians who prescribe opioid medications should first obtain a thorough patient history, particularly a list of other medications currently being taken by the patient that could potentiate these reactions. This includes over-the-counter medications and herbal supplements. Some herbal medications, such as kava kava and St. John's wort, have sedating qualities that can work synergistically with those of codeine or any opioid.
| A) | is a bacteriostatic medication. | ||
| B) | does not have a beta-lactam ring. | ||
| C) | interferes with bacterial DNA synthesis. | ||
| D) | may enhance the anticoagulant effects of warfarin. |
Originally noted by a French medical student in 1896 and rediscovered by Sir Alexander Fleming in 1928, it was not until the 1940s that penicillin became commercially available in the United States [37]. Chemically, penicillin and its derivatives all share a similar structure, including a beta-lactam ring; this structure is also the core of cephalosporin and monobactam antibiotics. Penicillins remain the antibiotic of choice for orofacial infections caused by aerobic, gram-positive streptococci and anaerobes. The bactericidal effect of penicillin is derived from its ability to interfere with the synthesis of components of the bacterial cell wall. The resultant decrease in the tensile strength of the bacterial cell wall causes weakening and cell rupture through osmotic lysis.
Penicillin is compatible with most medications, with a few noteworthy exceptions. The anticoagulant effects of warfarin may be increased with the simultaneous use of penicillin, potentially leading to coagulation difficulties. This could be a concern for patients who cannot discontinue warfarin prior to oral surgery and who are prescribed penicillin to treat or prevent odontogenic infection. In addition, the efficacy of oral contraceptives may be decreased in patients taking penicillin [18]. An alternative means of contraception or an alternative antibiotic is necessary for these women. Probenecid, which is used to treat hyperuricemia associated with gout or gouty arthritis, can decrease the excretion of penicillin and cause the plasma levels of the drug to rise [7].
| A) | Food will delay its absorption. | ||
| B) | Simultaneous use of allopurinol can cause a rash. | ||
| C) | Amoxicillin has a broader spectrum of microbial activity compared to penicillin V. | ||
| D) | It is currently the antibiotic of choice for prophylaxis against bacterial endocarditis. |
The addition of one amine group and one hydroxyl group and the deletion of one oxygen molecule is all that differentiates amoxicillin from penicillin V [40]. The addition of the hydroxyl group allows for amoxicillin to be absorbed faster than penicillin V, with more diffuse distribution through infected tissue and organic fluids. Food will not delay the absorption of amoxicillin, as it does with other penicillin medications [41]. This improvement has resulted in amoxicillin replacing penicillin as the antibiotic of choice for prophylaxis of bacterial endocarditis. Compared with penicillin V, amoxicillin has a broader spectrum of microbial activity.
Adverse drug interactions associated with amoxicillin parallel those of penicillin. Additionally, the simultaneous use of allopurinol in patients treated for gout can increase the potential for the development of a rash [18].
| A) | Penicillin | ||
| B) | Cephalexin | ||
| C) | Amoxicillin | ||
| D) | Clindamycin |
Alone, clavulanic acid has low antibacterial activity. However, when combined with amoxicillin, it extends the spectrum of bactericidal activity to include organisms that produce beta-lactamase. Infections that do not resolve with this medication generally require another class of antibiotic medications altogether. Available under the brand name Augmentin or Amoclan, this combination can be prescribed in various dosage forms, including an 875 mg tablet taken once every 12 hours [18]. Possible interactions and side effects are the same as for those of amoxicillin, with the additional concern of clavulanic acid allergy.
| A) | can have adverse interactions with metformin. | ||
| B) | have a beta-lactam component to their structure. | ||
| C) | have cross-reactivity in patients allergic to penicillin. | ||
| D) | All of the above |
Cephalexin is a semi-synthetic medication that shares the beta-lactam structure of both penicillin and amoxicillin. Cephalexin and other first-generation cephalosporins are less susceptible to beta-lactamase as compared to penicillin and amoxicillin and provide reasonable coverage against pathogenic oral flora [42]. It is most effective against aerobic, gram-positive bacteria. First introduced in 1967, cephalexin remains among the most frequently prescribed antibiotics in North America [43]. It can be utilized as antibiotic prophylaxis for bacterial endocarditis for those allergic to amoxicillin or clindamycin. Patients who are allergic to penicillin have a potential cross-reactivity to cephalexin. In particular, if the reaction to penicillin was immediate and anaphylactic, there is a 20% chance that there will be a cross reactivity between these two medications; in these cases, cephalexin is absolutely contraindicated [7]. If the reaction to penicillin had a delayed onset, the risk that the patient is also allergic to cephalexin is only 1%.
The most common adverse effects are similar to those described for penicillin and amoxicillin. Additionally, central nervous system symptoms such as dizziness, confusion, and fatigue can occur [18]. A unique drug interaction not seen with other beta-lactam antibiotics is seen with cephalexin and the oral hypoglycemic medication metformin, commonly used in patients with type 2 diabetes. The simultaneous use of these drugs can decrease the renal clearance of metformin, thereby increasing its plasma concentration. This can result in a decrease in blood glucose levels to a range that could precipitate a hypoglycemic crisis, especially if the patient has not eaten [18].
| A) | has a beta-lactam ring. | ||
| B) | causes breakdown of bacterial cell walls. | ||
| C) | is not used for prophylaxis against bacterial endocarditis. | ||
| D) | is actively transported into macrophages and leukocytes. |
Clindamycin is a derivative of lincomycin and acts to inhibit bacterial protein synthesis by binding to the 50S ribosomal RNA (rRNA) subunit of susceptible bacteria; thus, it is bacteriostatic rather than bactericidal [18,44]. Clindamycin is readily absorbed from the gastrointestinal tract and is distributed effectively to most tissues. It is actively transported into macrophages and leukocytes, both of which are highly concentrated in abscesses [45]. It has become the antibiotic of choice for prophylaxis against bacterial endocarditis for patients who cannot take amoxicillin [18].
| A) | Cephalexin | ||
| B) | Amoxicillin | ||
| C) | Tetracycline | ||
| D) | Clindamycin |
One of the most notable side effects of tetracycline and its derivatives is irreversible staining of the developing permanent teeth. Therefore, tetracyclines should not be taken by women who are pregnant or nursing or children 8 years of age or younger [18]. As with the other antibiotics, drug interactions include an increase in the anticoagulant effect of warfarin and decreased efficacy of oral contraceptives.
| A) | 5% to 15% | ||
| B) | 9% to 31% | ||
| C) | 11% to 60% | ||
| D) | 80% to 90% |
In dental patients, antifungals are mainly used to treat oral candidiasis, an infection that can develop secondary to various underlying causes. Candida albicans is the primary fungal organism among the oral flora that proliferates to cause oral and pharyngeal candidiasis. The Centers for Disease Control and Prevention has listed oral candidiasis as an acquired immunodeficiency syndrome (AIDS)-defining illness [51]. An estimated 80% to 90% of patients with AIDS will develop oral candidiasis at some time during the progression of their disease [52]. In addition, patients taking oral antibiotics can develop an opportunistic case of oral candidiasis due to imbalances in the oral flora. Patients with other forms of immunosuppression, such as those taking chemotherapy, organ or bone marrow transplants recipients who require immunosuppressive medications for life, poorly controlled diabetics, and postradiotherapy oral cancer patients with a permanent reduction in salivary flow, are all susceptible to initial and recurring cases of oral candidiasis. This section will discuss the most common antifungal medications used to treat oral candidiasis. Some cases can be refractory to conventional oral antifungal medications and require more intensive treatment. Disseminated fungal infections among immunocompromised patients are associated with a high morbidity rate and even fatal termination. Oropharyngeal candidiasis that does not resolve with polyene or azole antifungal agents should be referred to a medical professional immediately.
| A) | formulations contain no sugar. | ||
| B) | is intended to treat systemic fungal infections. | ||
| C) | is readily absorbed from the gastrointestinal mucosa. | ||
| D) | has an oral suspension that should be used in a swish-and-swallow protocol. |
Typically, the adult dose of the oral suspension of nystatin for the treatment of oral candidiasis is 400,000–600,000 units four times every day [18,53]. A swish-and-swallow protocol is utilized, as fungal organisms that have extended toward the esophagus can be treated as the oral suspension is swallowed. This regimen is followed for an average of 7 to 10 days. Nystatin is also available as a dissolvable troche that contains 200,000–400,000 units of the drug, usually taken four to five times daily [18,53]. Patients using this formulation should be advised to remove any oral prosthesis to allow adequate contact between the oral mucosa and the dissolving troche. The ability of the nystatin troche to work properly depends on an adequate salivary medium, so any medication or condition that diminishes salivary gland output can decrease the efficacy of this formulation.
A topical ointment formulation of nystatin can be used to treat the mucocutaneous candidal infection angular cheilitis, which occurs at the corners of the mouth. The oral suspension and troche formulations will have inadequate access and contact time with this area. The topical version of nystatin can be combined with triamcinolone, a synthetic corticosteroid, to reduce the inflammation associated with this condition.
| A) | Food precludes the absorption of fluconazole. | ||
| B) | It can decrease the anticoagulant effect of warfarin. | ||
| C) | It can decrease serum concentrations of diazepam. | ||
| D) | It is used in cases where fungal resistance is suspected. |
Fluconazole is available in both oral tablets and IV formulations, with oral administration most commonly used in the treatment of oropharyngeal candidiasis. It is indicated to treat oral candidal infections that have not responded to nystatin, candidiasis in patients with impaired immunocompetence, or infections with suspicion of antifungal resistance. Fluconazole is well distributed to all tissues, and food does not preclude its absorption. If hepatic or renal problems exist, fluconazole can exacerbate these issues [18].
The most common side effects of fluconazole are diarrhea, nausea, vomiting, headache, and dizziness. Fluconazole is taken once daily, and the duration of therapy and the strength of the prescribed dose will vary with the extent of fungal involvement and the patient's response to therapy. For typical, uncomplicated oropharyngeal candidiasis, the usual initial dose in adults is 100–200 mg daily for 7 to 14 days [7,53].
Many medications can interact adversely with fluconazole, and a discussion of all possible drug interactions is beyond the scope of this course; only the most common will be discussed here. Fluconazole can enhance the anticoagulant effect of warfarin, so patients' international normalized ratios should be monitored if these medications are used simultaneously. The serum concentration of calcium channel blockers, a class of medications used to treat hypertension, can rise when taken concurrently with fluconazole [18]. This can result in excessive reduction in blood pressure and hypotension. If neither medication can be changed, consult a physician to determine if a temporary dose reduction of the calcium channel blocker can be prescribed. In addition, the serum concentrations of anxiolytic medications such as triazolam and diazepam are increased with the concomitant use of fluconazole, which can result in excessive sedation [54]. Before fluconazole is prescribed, it is imperative that the clinician is aware of the potential interactions to medications the patient is already taking.
| A) | It must be swallowed to be effective. | ||
| B) | The troches have a high sugar content. | ||
| C) | It is readily absorbed for systemic distribution. | ||
| D) | The usual dose is one troche per day for up to seven days. |
Clotrimazole is an azole antifungal available as a topical cream or troches. The troches, manufactured as a 10-mg dose, must be dissolved slowly in the mouth for the treatment of oropharyngeal candidiasis, as there is no systemic absorption if it is swallowed [7]. The usual dose is four or five troches per day for up to 14 days, with the extent of the oral candidiasis dictating the cumulative daily dose and duration [18,53]. The troches contain a significant amount of sugar, so adherence to good oral hygiene practices should be emphasized while they are being used.
| A) | Acyclovir is available in an oral formulation only. | ||
| B) | Valacyclovir is available in oral and intravenous formulations. | ||
| C) | Acyclovir has a higher bioavailability compared to valacylovir. | ||
| D) | Acyclovir may be used in the treatment of oral hairy leukoplakia. |
Unlike antibiotic or antifungal medications, which target the cell wall or cell membrane, acyclovir becomes incorporated into the viral DNA and prevents further viral replication. Acyclovir and its derivatives are highly selective for viral DNA, so collateral damage to the host mammalian cells is spared [42]. The bioavailability of oral acyclovir is low, ranging from 10% to 20% [18]. While oral and topical formulations are prescribed most frequently, intravenous acyclovir is also available for patients whose immunosuppression is conducive to a longer and more virulent HSV-1 course. The topical form of acyclovir decreases viral shedding and can be applied directly to the lesion with a special applicator. Patients should be advised to avoid direct contact between the fingertips and the viral lesions. Viral inoculation of the finger can result in the development of recurrent herpetic outbreaks of the finger known as herpetic whitlow. Oral acyclovir is taken in either 200- or 400-mg doses three to five times per day [7]. The duration of treatment is determined by the extent of viral involvement. The medication may also be used to suppress future outbreaks.
Possible side effects of oral acyclovir include abdominal cramping, nausea, and vomiting. Simultaneous use of the antiviral medication zidovudine, which is used to treat HIV/AIDS patients, or probenecid, used to treat gout, can lead to adverse central nervous system effects [7].
Oral acyclovir may also be used to treat oral hairy leukoplakia, characterized by bilateral lesions on the lateral surfaces of the tongue. These corrugated white lesions are painless and fixed to the underlying tissue and arise as a result of reactivation of the Epstein-Barr virus in immunosuppressed patients. These lesions will regress with acyclovir therapy but often return upon its cessation.
| A) | They have short half-lives. | ||
| B) | They have a rapid onset after oral administration. | ||
| C) | They can potentiate the respiratory depression of narcotic analgesics. | ||
| D) | Their metabolism and excretion can be decreased by renal and hepatic pathologies. |
Diazepam was the second benzodiazepine medication ever developed, first becoming available in 1963. Today, it is one of the core medications in the World Health Organization's Model List of Essential Medicines [56]. The bioavailability after oral administration is 90%, and peak plasma levels occur 15 minutes to 2.5 hours after oral administration, allowing for a rapid onset of action [18]. When used as an anxiolytic medication before dental treatment, it may be taken both the night prior and one hour before the appointment. The dose depends upon the degree of anxiety, the patient's weight, concurrent use of other medications, and pertinent factors in the patient's medical history. The degree of sedation varies among individuals, so patients should not drive to or from their dental appointments if this drug is used. Diazepam has a lengthy half-life of 44 to 48 hours; the half-life of its active major metabolite, desmethyldiazepam, is 100 hours [18]. This extended half-life results in a protracted period of varying degrees of sedation, and any activity that would endanger the patient during this interval (e.g., operating heavy machinery) should be avoided.
Among the most common medical conditions that preclude the use of diazepam for sedation are severe respiratory disorders, alcohol or drug dependence, liver disorders, and renal disorders [18]. Hepatic pathologies such as hepatitis and cirrhosis impede the metabolism of diazepam and can allow accrual of the drug, causing excessive sedation and potential toxic accumulation. Similarly, renal impairment can decrease the excretion of diazepam and allow serum drug levels to remain high. Gastrointestinal side effects, such as nausea, vomiting, and constipation, can occur. Possible adverse central nervous system effects include amnesia, confusion, excessive sedation, and paradoxical excitement [18].
Diazepam has the potential for many adverse interactions with other medications, including some medications prescribed for oral health issues. Diazepam increases the depressive effect of narcotic analgesics and can exacerbate respiratory depression [18]. Simultaneous use of ketoconazole can decrease the elimination of diazepam and prolong its effect [57]. Patients who consume alcoholic beverages while taking diazepam can experience advanced sedation and hypotension. Before diazepam is administered for anxiolytic purposes, patients should be informed of its potential side effects and adverse medication interactions.
| A) | 0.01 mg. | ||
| B) | 0.25 mg. | ||
| C) | 0.5 mg. | ||
| D) | 1 mg. |
Triazolam, also a benzodiazepine drug, has been available in the United States since 1982. Triazolam has a rapid onset of action and a significantly shorter half-life (two to five hours) compared to diazepam. Therefore, there is a decreased potential for protracted sedation with this medication [18]. Triazolam can be administered sublingually the night before a dental appointment to promote good sleep and one hour before the appointment for anxiolytic purposes, although this use is off label [7]. The usual dose is 0.25 mg, with a maximum cumulative dose of 0.5 mg/day [18]. Unlike diazepam, triazolam has no active metabolites and does not cause extended sedation. In fact, the sedative effect of an initial dose of triazolam may not be sufficient for longer appointments. However, extreme caution must be used in the administration of additional doses of this medication. At least 90 minutes should elapse before even the lowest second dose (0.125 mg) is provided [58]. Given the variability in action among patients based on the degree of anxiety, weight, and medical history, excess sedation can occur in some patients even before the maximum cumulative dose is reached. The lowest possible initial and cumulative doses necessary to attain the desired sedative effect should be used.
| A) | Anxiety | ||
| B) | Emphysema | ||
| C) | Air embolus | ||
| D) | Pneumothorax |
Unlike the first uses of pure nitrous oxide, conventional dental use of this gas today is combined with varying percentages of oxygen. A typical mixture is 30% nitrous oxide and 70% oxygen, with other proportionate combinations also used. This combination of gases rapidly diffuses into the bloodstream and is eliminated at the end of the session when pure oxygen is inhaled for five minutes; it is not metabolized by the body and is secreted essentially unchanged via the lungs. There are no known significant drug interactions, although there is some evidence that nitrous oxide may increase the risk of methotrexate-associated toxicity [7,62,63]. Common side effects are postprocedural nausea and vomiting. Absolute contraindications to nitrous oxide use include emphysema, pneumothorax, middle ear surgery, air embolus, elevated intracranial pressure, and methionine synthase pathway enzyme deficiencies [64]. Renal, hepatic, and neurologic problems may be noted, and fertility issues can develop in women exposed to multiple doses of nitrous oxide [18].
| A) | Age and weight of the patient | ||
| B) | The presence of chronic illnesses | ||
| C) | The current use of other medications | ||
| D) | All of the above |
Many factors can influence the absorption, distribution, metabolism, and excretion of medications, and before any medication is administered, these factors must be considered. The patient's weight, health issues, other prescribed medications, and current condition will influence the dose, frequency of administration, and duration of use of medication(s). The medical history should be updated with each patient visit, including information about any problematic experience that the patient has had with the use of prescribed or over-the-counter medications.
Systemic health issues will influence the choice of medications as well. Patients with hepatic problems, such as hepatitis or cirrhosis, often have decreased liver function and impaired ability to metabolize medications. Similarly, renal pathology can decrease the excretion of medications and allow a detrimental drug accumulation. In these patients, dose, frequency of administration, and the duration of treatment should be adjusted to prevent toxic accumulation or overdose of a given medication. Patients taking multiple medications for complex medical problems face the challenges of adverse drug interactions, inadequate drug metabolism, and impaired drug excretion. Consult the patient's physician if there are any concerns about prescribing additional medications for these patients.