drugs used in dentistry

[dr.amr]

اقتباس المشاركة الأصلية كتبت بواسطة dr.amr البقيه الان

Codeine
As with all opioids analgesics, the analgesic and antitussive actions of codeine (as well as its respiratory depressant and sedative effects) are central in origin. Codeine is frequently classified as a "weak" or "mild" opioid analgesic. That codeine is a mild analgesic incapable of providing an analgesic effect equivalent to morphine is an erroneous, but widely held, impression. Morphine as an analgesic is about 12 times more potent than codeine when both drugs are administered intramuscularly. This ratio simply means that approximately 120 mg of codeine is required to produce an analgesic effect equivalent to 10 mg of morphine. At the present time, however, doses of codeine in excess of 60 mg (orally) are not commonly used and, moreover, are not officially recognized as generally safe and effective by the Food and Drug Administration. Consequently, the impression remains that codeine has limited analgesic efficacy and that a dose of 60 mg of codeine represents an "analgesic ceiling" above which increasing doses will not provide greater analgesic effect.

It should be noted, however, that dental pain associated with inflammation should not be treated with codeine alone because neither codeine nor any of the other opioids has antiinflammatory properties. Rather, aspirin or another nonsteroidal antiinflammatory drug alone or in combination with codeine is appropriate for cases of dental pain involving or arising from inflammation.

[dr.amr]

خلاص اصلا والله الموضوع طويل واصلا هاذا ملخص فما اقدر احذف شي كل المعلومات مهمه

وبكره حكمل باقي الادويه اللي في الاسنان

[dr.amr]

اقتباس المشاركة الأصلية كتبت بواسطة dr.amr خلاص اصلا والله الموضوع طويل واصلا هاذا ملخص فما اقدر احذف شي كل المعلومات مهمه وبكره حكمل باقي الادويه اللي في الاسنان

Principles of Opioid Analgesic Use

Analgesics should be administered initially on a regular time schedule. For example, if the patient is likely to have pain requiring analgesics for 48 hours after dental surgery, analgesics might be ordered every 4 hours while awake, not as needed (pro re nata or prn), for the first 36 hours. This schedule provides more stable plasma concentrations of the agent with less breakthrough pain. If only prn medications are used, it may take several hours and higher doses to relieve pain, leading to a cycle of undermedication and pain alternating with periods of overmedication and drug toxicity. Later in the postoperative course, as the patient's analgesic dose requirement diminishes, dosing may be switched to an as-needed basis.
Adverse Reactions of Opioids

Unlike many drugs, the adverse reactions of the opioids are not related to a direct damaging effect on hepatic, renal, or hematolgic tissues but rather are an extension of their pharmacologic effects. Like the pharmacologic effects, the adverse reactions of the opioid analgesics are proportional to their analgesic strength.

1. Respiratory depression. The opioid analgesic agonists depress the respiratory center in a dose-related manner. This is usually the cause of death with an overdose.

2. Nausea and emesis. Analgesic doses of opioid analgesics often produce nausea and vomiting. This is due to their direct stimulation of the chemoreceptor trigger zone (CTZ) located in the medulla. This side effect is reduced by discouraging ambulation.

3. Constipation. The opioids produce constipation by producing a tonic contraction of the gastrointestinal tract. Small doses of even weak opioids frequently have this effect and its duration outlasts their analgesic effect. Even with continued administrations tolerance does not develop to this effect.

4. Urinary retention. The opioids increase the smooth muscle tone in the urinary tract, thereby causing urinary retention. They also produce an antidiuretic effect by stimulating the release of antidiuretic hormone (ADH) from the pituitary gland.

5. CNS effects. Occasionally, opioids may produce CNS stimulation exhibited by anxiety, restlessness, or nervousness.
Combinations of Peripherally Acting Analgesics and Opioids
There is a sound scientific basis for combining peripherally acting analgesics with opioids. The peripherally acting drugs combat pain principally by directly interfering with the biochemical mediators that cause sensitization of nerve endings at the site of injury, whereas the opioids alter CNS perception and reaction to pain. The mechanisms of pain relief of these two classes of drugs are distinct, supporting the use of these two types of drugs in combination. In addition to the fact that these combinations seem reasonable, abundant clinical data exists to support the validity of their combined use. However, there is a common misconception that such combinations produce a synergistic phenomenon, that is, an effect greater than the sum of effects expected from both drugs. No evidence currently supports this belief, and, at best, there is purely additive effect when drugs from these two classes of analgesics are combined. Indeed, if any synergism does exist, it is probably with the toxic effects rather than with analgesic efficacy.

Another misconception is that the opioid in the combination is the major contributor to the overall effectiveness of the oral preparation for the treatment of dental pain. Clinical studies indicate quite the opposite, showing that the peripherally acting component is an equal or, more often, greater contributor to the overall efficacy of the combination for most types of pain. When one limits the comparison to those studies evaluating pain of dental etiology, there is no question that the aspirin like drugs provide the bulk of the pain relief, whereas the opioids are of less benefit. When side effects are compared, however, the centrally acting drugs are most often the cause.

The clinical significance of the centrally acting analgesics is that they provide additional analgesia beyond the ceiling effect of the peripherally acting component, and they also contribute a centrally mediated sedative effect. Therefore, the most effective combinations are those that use the optimal amount of an aspirinlike drug combined with the appropriate dose of an opioid analgesic.

Codeine is the most commonly used centrally acting agent in combination analgesics. Its effective oral dose range is 30 to 90 mg, 30 mg providing only minimal analgesia, 60 mg providing a little more analgesia with considerably more nausea and sedation, and 90 mg approaching the dose at which intolerable side effects appear. Codeine is available in combination with aspirin or acetaminophen. For most patients, 600 to 650 mg of the peripherally acting component combined with either 30 or 60 mg of codeine should provide adequate pain relief for almost any acute dental pain.

There are other centrally acting analgesics used in combination, but the vast majority of drug combinations on the market include codeine, oxycodone, hydrocodone, propoxyphene, or pentazocine combined with either aspirin or acetaminophen.
The advent of the NSAIAs has produced a dramatic decrease in the use of the opioids in dental practice. Most dental pain can be better managed by the use of NSAIAs. In the patient in whom NSAIAs are contraindicated, the dentist has a wide range of opioids from which to choose. By beginning with codeine or hydrocodone combinations and progressing to oxycodone combination, almost all dental pain can be managed. Only in rare cases, and for very short periods of time (1 to 2 days), should hydromorphone or meperidine be prescribed for outpatient dental pain.

Dentists should be familiar with several analgesics in both the opioid and nonopioid categories. Different patients vary greatly in their response to, and ability to tolerate, different agents. For this reason, it is important to be familiar with the recommended dose, side-effect profile, and time course of several agents in each category.

Patient should be followed closely, particularly when beginning or changing analgesic regimens. Analgesics are more beneficial if the clinician monitors pain relief and adverse effects frequently and adjusts the regimen as needed to optimize therapy. This monitoring is particularly important when using an agent or combi-nation with which the doctor has little or no experience or when changing from one analgesic to another.

Although pain is a common occurrence in patients seeking or undergoing dental care, it is generally manageable and often avoidable. Accurate assessment, methodical prevention, and aggressive treatment are the tools required to keep pain at a minimum. Rational clinical practice guidelines and equianalgesic charts allow practitioners to determine the appropriate analgesic regimen and dose for each patient.

[dr.amr]

اقتباس المشاركة الأصلية كتبت بواسطة dr.amr خلاص اصلا والله الموضوع طويل واصلا هاذا ملخص فما اقدر احذف شي كل المعلومات مهمه وبكره حكمل باقي الادويه اللي في الاسنان

Antianxiety Drugs

Fear and anxiety of dentistry are common. The severity ranges widely, with mild apprehension being reported by as many as 75% of the population and severe anxiety, leading to avoidance of dental treatment, affecting anywhere from 6% to 20%. Although mild fear may have only a minor impact on oral health, true phobia can cause patient to avoid treatment in spite of significant symptoms and to have detrimental consequences for their overall health.
Antianxiety drugs are used in clinical dentistry primarily for premedication of the nervous and apprehensive patient.
The usefulness and effectiveness of any given antianxiety agent will vary, depending on the patient, the clinical surroundings, the "chairside" manner of the dentist, the route of administration, and the properties of the chosen drug.

Benzodiazepines

The benzodiazepines rank as the one of the most widely used drug classes in the history of medicine. This popularity stems from the fact that they are more selective and have a greater margin of safety than drugs used earlier (e.g., barbiturates) for the treatment of anxiety. Currently, there are several dozen benzodiazepines being marketed throughout the world.
Pharmacologic effects The most important pharmacologic effects of the benzodiazepines are on the CNS. The benzodiazepines have clinically useful antianxiety, sedative-hypnotic, anticonvulsant, and skeletal muscle relaxant properties. The clinical effects of these agents in humans are anxiety reduction at low doses and production of drowsiness, and even sleep at higher doses.

The benzodiazepines, particularly diazepam, have anticonvulsant activity (i.e., they increase the seizure threshold). Diazepam has been shown to be an effective anticonvulsant for the prevention of seizures associated with local anesthetic toxicity and for the treatment of status epilepticus.

Many of the gross CNS effects of the benzodiazepines are similar to those of the older sedative-hypnotics, such as the barbiturates. All of the benzodiazepines produce a dose-dependent depression of the CNS. Drowsiness and sedation are common manifestations of this central depressant action and may be considered a side effect in some instances and therapeutically useful in others.

As is true of any sedative drug, the benzodiazepines are respiratory depressants. In normal doses the benzodiazepines have little effect on respiration in the healthy person.
Adverse effects The most common side effect of the benzodiazepines is drowsiness. This may not necessarily be an unwanted side effect, but rather a desirable therapeutic response to anxiety states that cause insomnia. Other side effects that are a result of dose-dependent CNS depression include ataxia, incoordination, dysarthria, confusion, apathy, muscle weakness, dizziness, and somnolence. The elderly (over 65 years) appear to be particularly susceptible, and persons with a history of alcohol or barbiturate abuse particularly resistant, to the CNS depressant properties of the benzodiazepines. The elderly and the young occasionally respond to the benzodiazepines with excitement rather than depression.

Tolerance and psychologic dependence occur rather frequently with the benzodiazepines, but true physical dependence is less common. Nevertheless, the abuse potential of the benzodiazepines is considerable. In cases of physical dependence, the severity of withdrawal depends on the dose of the drug being used and the drug half-life. Rapid discontinuation of the benzodiazepines, especially the short-acting compounds, can lead to symptoms of withdrawal.

The symptoms become more severe with high doses and prolonged treatment. Withdrawal can be minimized by reducing the dosage very gradually (10% or less per day over a course of 10 to 14 days) or by the use of longer-acting compounds.
Despite these problems, one of the major advantages of the benzodiazepines, as compared to other sedatives, is their high margin of safety. Death is rare in cases of overdose and is usually the result of a combination of drugs (especially alcohol) with the benzodiazepines.

The antianxiety agents are important in dentistry for the premedication of the apprehensive patient, the patient exhibiting mild neurosis associated with the mouth, and the uncooperative child. Antianxiety agents, particularly intravenous midazolam and diazepam, are used as adjuncts to local anesthesia.
Perhaps one of the more perplexing questions for the practicing dentist is which oral benzodiazepine to choose from the overexpanding list. There is little doubt of the clinical effectiveness of these drugs in a variety of dental procedures, but there are no unusual characteristics associated with any one benzodiazepine that would make it clearly superior to the others. The major decision to be made in the treatment of the anxious patient is therefore not which drug to use but rather when to administer.

The primary concern of the dentist in using an antianxiety agent should be excessive CNS depression. CNS depression may result from the antianxiety agent alone or its combination with other CNS depressants that the dentist may plan to give or that the patient may already have taken. The antianxiety agents summate with the anesthetics, antipsychotics, antidepressants, opioid analgesics, and sedative-hypnotics. Alcohol may markedly increase the CNS depressant effects of benzodiazepines.

[dr.amr]

[dr.amr]

اقتباس المشاركة الأصلية كتبت بواسطة dr.amr خلاص اصلا والله الموضوع طويل واصلا هاذا ملخص فما اقدر احذف شي كل المعلومات مهمه وبكره حكمل باقي الادويه اللي في الاسنان

Autonomic Nervous System Drugs

It is important that the dentist becomes familiar with the autonomic nervous system (ANS) drugs used in dentistry, such as vasoconstrictors in local anesthetic solutions and drugs used to reduce salivary flow. The dentist should know the oral adverse reactions produced by ANS drugs and should be able to distinguish similar reactions produced by other drugs such as antihypertensives and antipsychotic drugs.

The autonomic nervous system (ANS) and the endocrine system comprise the major regulatory system for controlling homeostatic functions. These two systems collectively regulate and coordinate the cardiovascular, respiratory, gastrointestinal, renal, reproductive, metabolic, and immunologic systems. Accordingly, drugs that alter the activity of either the ANS or the endocrine system often exhibit multiple actions and side effects.
The ANS regulates the function of involuntary structures: smooth muscle, secretory glands, and cardiac muscle. These structures possess intrinsic mechanisms that make it possible for them to function in the absence of innervation, but the ANS contributes a regulatory and coordination function.

The ANS functions largely as an automatic modulating system for many bodily functions including the regulation of blood pressure, heart rate, gastrointestinal tract motility, salivary gland secretions, and bronchial smooth muscle. This system relies on specific neurotransmitters and a variety of receptors to initiate functional responses in the target tissues. The ANS has two divisions, the sympathetic autonomic nervous system (SANS) and the parasympathetic autonomic nervous system (PANS).

These two divisions of the ANS tend to act in opposite directions. The sympathetic division is designed to cope with sudden emergencies, such as, "fight or flight" situations. In contrast, the parasympathetic division is concerned with the conservation of body processes. Working generally in opposite directions, one would increase the heart rate while the other decreases it, one would dilate the pupils and the other would constrict them.
There are four groups of drugs that exert their effects primarily on the ANS.

1. Cholinergic agents or parasympathomimetics mimic the effects of the parasympathetic nervous system.

2. Anticholinergic agents, parasympatholytics, or cholinergic blocking agents block the effects of the parasympathetic nervous system.

3. Adrenergic agents or sympathomimetics mimic the effects of the sympathetic nervous system.

4. Adrenergic or sympathetic blocking agents, or sympatholytics, block the effects of the sympathetic nervous system.

Cholinergic (Parasympathomimetic) Agents

The cholinergic (parasympathomimetic) agents are classified as direct acting and indirect acting depending upon their mechanism of action. The direct-acting agents include the choline-derivatives and pilocarpine.

The indirect-acting parasympathomimetic agents or cholinesterase inhibitors act by inhibiting the cholinesterase. When this enzyme, which normally destroys acetylcholine, is inhibited, the concentration of acetylcholine builds up, resulting in action that resembles PANS stimulation.

The direct-acting agents as well as indirect-acting agents are used primarily in the treatment of glaucoma and, occasionally, to treat myasthenia gravis, a disease resulting in muscle weakness. The urinary retention that occurs after surgery is also treated with the choline esters.

Anticholinergic (Parasympatholytic) Agents

The anticholinergic agents prevent the action of acetylcholine at the postganglionic parasympathetic endings by completely blocking the receptor sight. These agents are used in preoperative medication, treatment of gastrointestinal disorders, ophthalmologic examination, reduction of Parkinson-like movements, motion sickness medication, over-the-counter sleepaids, and in dentistry to produce a dry field before some dental procedures.

Neuromuscular Blocking Drugs

Neuromuscular blocking drugs are agents that affect transmission between the mortar nerve endings and the nicotinic receptors on the skeletal muscle. They include known depolarizing blockers and depolarizing agents.

Adrenergic Drugs

Vasoconstrictors are widely used in conjunction with local anesthetic solutions. The vasoconstrictor most commonly employed in dentistry is l-epinephrine, with levonordefrin (the l isomer of nordefrin) being employed somewhat less frequently, usually with mepivacaine. Norepinephrine is only rarely used for this purpose.

The table below lists the concentrations and amounts of adrenergic vasoconstrictors contained in commercially available dental local anesthetic cartridges. The maximum recommended strength of the vasoconstrictor is 1:100,000 epinephrine equivalency for routine nerve block anesthesia. When local tissue hemostasis is required for surgical procedures, such as periodontal surgery, the dentist may additionally choose to infiltrate the area with local anesthetic solution containing up to 1:50,000 epinephrine.

Vasoconstrictors serve several useful purposes when employed with local anesthetic solutions. First, they prolonged the duration of local anesthesia severalfold and may improve the frequency of successful nerve block. Second, toxicity of the local anesthetic may be minimized by delaying and reducing the peak blood concentration of the anesthetic agent. Third, when anesthetic solutions are given by infiltration, vasoconstrictors tend to reduce blood loss associated with surgical procedures.
With a working knowledge of the ANS and the role it plays in the normal function of the various organs, it is possible to predict what effects a drug with a known mechnism of action would have.

[dr.amr]

[dr.amr]

باقي قليل...............واكمل

[dr.amr]

اقتباس المشاركة الأصلية كتبت بواسطة dr.amr باقي قليل...............واكمل

Adverse effects Almost all adverse effects of the adrenergic amines are dose related. Toxic reactions can result from the administration of too large a dose, accidental intravascular injection, impaired uptake of the drug, a heightened sensitivity or number of adrenergic receptors, or therapeutic doses given to a patient with preexisting cardiovascular disease. Relatively small amounts of epinephrine can cause potentially grave effects in the highly susceptible patient. In general, however, serous complications may be expected with doses of epinephrine above 0.5 mg, and fatalities are likely to occur with doses of 4 mg. or more. Correct dosage calculations, careful reading of labels, and a complete medical history can help reduce accidents.
Most serious of the toxic effects of epinephrine are cardiac disturbances, with increased stimulation of the heart leading to myocardial ischemia, possible heart attack, and arrhythmias, including ventricular fibrillation.

Adrenergic Blocking Drugs
Agents that suppress functions of the sympathetic nervous system, as well as those that block the actions of exogenous adrenergic amines, have a number of important implications for the practice of dentistry. Usually, these drugs are used in major cardiovascular disease, signaling the dentist's need to pay heed to potential risks associated with the condition. Drug therapy with any of these blocking drugs results in a patient whose autonomic capability for maintaining homeostasis has been altered. These changes may alter responses to sympathetic drugs and may lead to characteristic adverse effects.

A consideration for patients being treated with adrenergic blocking drugs is the patient's position during and after dental procedures. Suddenly standing upright after being in a supine position in the dental chair is very apt to cause syncope.
This is particularly true for the antihypertensive drugs more prone to cause orthostatic hypotension. Accidents ranging from broken teeth and restorations to fractured mandibles and worse have resulted from falls. Contemporary practice standards require the monitoring of blood pressure in dental patients. Such monitoring is particularly important in hypertensive patients.

Increasingly, incidents are occurring in which dentists are not informed of patients receiving medication from another practitioner in which there is a change in drug therapy or dosage. With the drugs that interrupt sympathetic function, this lack of knowledge can have serious consequences. Patients taking MAO inhibitors must not be given drugs that have indirect sympathomimetic activity or are inactivated by MAO. Occasionally, the dentist may find reason to use the vasoconstrictor phenylephrine. Because it causes even a minor release of norepinephrine from adrenergic nerves and is subject to metabolism by MAO, phenylephrine must be avoided in patients taking MAO inhibitors. Epinephrine and levonordefrin, which are most commonly found in local anesthetic solutions, are contraindicated. Nonetheless, the avoidance of hemostatic preparations containing high concentrations of epinephrine is recommended. Opioids and other CNS depressants should be used cautiously and usually at lower doses in patients who are taking MAO inhibitors. Meperidine is absolutely contraindicated.

[dr.amr]

اقتباس المشاركة الأصلية كتبت بواسطة dr.amr باقي قليل...............واكمل

Local Anesthetics

Local anesthetics are agents that reversibly block nerve conduction when applied to a circumscribed area of the body. Although numerous substances of diverse chemical structure are capable of producing local anesthesia, most drugs of proven clinical usefulness (identified by the suffix "caine") share a fundamental configuration with the first true local anesthetic, cocaine.

Local anesthetics block the sensation of pain by interfering with the propagation of peripheral nerve impulses. Both the generation and the conduction of action potentials are inhibited.
Vasoconstrictors are often added to local anesthetic solutions to impede systemic absorption of the anesthetic agent. Epinephrine in concentrations of 4 to 20 mg/mL (1:250,000 to 1:50,000) is most commonly used for this purpose. Localization of the anesthetic solution in the area of the injection by epinephrine is often highly beneficial. The duration of local anesthesia may be prolonged severalfold, and even the success rate and intensity of nerve block may be improved. Systemic toxicity may be reduced because less anesthetic may be needed, and drug metabolism is more likely to keep pace with drug absorption. During surgery, hemostasis afforded by the infiltration of a local anesthetic solution containing epinephrine may also be advantageous.

Modern local anesthetic solutions are quite safe when employed by competent personnel. Most toxic effects of a serious nature are related to excessive blood concentrations caused by inadvertent intravascular injection or the administration of large quantities of drug. Convulsions, respiratory depression, and cardiovascular collapse represent the greatest hazards to health. Such reactions can usually be prevented by observing three precautions: (1) administer the smallest dose that will provide effective anesthesia; (2) employ proper injection techniques, including aspiration; and (3) use a vasoconstrictor-containing solution when not contraindicated by patient history or operative need. If an adverse response occurs despite these procedures, immediate therapy must be administered. The patient should be placed in the supine position, and oxygen should be given. This procedure is often all that is needed for mild toxic reactions, epinephrine responses, or syncopal attacks.

Convulsions are usually self-limiting and require no treatment other than supporting ventilation and protecting the patient from bodily harm. Pharmacologic intervention is necessary, however, when seizures are so intense or prolonged that hypoxia threatens to ensue. The most satisfactory method of seizure control for the dentist is the intravenous administration of a rapidly acting benzodiazepine.

Local anesthetics are generally regarded as safe for use throughout pregnancy, and retrospective studies of women receiving local anesthesia for emergency procedures in the first trimester have supported this view.

It would be difficult to overstate the profound influence of local anesthesia on the practice of dentistry. Many of the complex restorative procedures routinely performed on conscious patients would be inconceivable without effective pain control. By eliminating most nociceptive sensations associated with dental care, local anesthetics improve patient acceptance of dental treatment and, as a result, contribute significantly to oral health. Because local anesthetics are so frequently employed and, for many practitioners, represent the only drugs administered parenterally, the toxicity as well as efficacy of these agents is of particular interest and concern.

Without question, local anesthesia is often considerably safer in dentistry than in medicine. Dosage employed for infiltration and nerve block in the oral cavity are often less than one-tenth those used for compound nerve block or for epidural injection. Recipients of dental anesthesia are in better systemic health than some medical patients and usually undergo only minor operative stress.

Selection of a local anesthetic for dental application must include considerations of efficiency, safety, and individual patient and operative needs. Indeed, 2% lidocaine hydrochloride with 1:100,000 epinephrine remains unsurpassed as dental anesthetic for routine use.

Anesthetics in Surface Application
Topical anesthetics are used in the oral cavity for a variety of purposes. Formulations marketed as pressurized sprays produce widespread surface anesthesia appropriate for making impressions or intraoral radiographs. Such preparations are potentially hazardous, however, and only products with metered valve dispenser to help prevent inadvertent overdose should be employed. Topical liquids, which avoid the possibility of aerosol inspiration, may also be used for anesthetic coverage of large surface areas. Nonaqueous topical preparations are suitable for most other procedures.

Benzocaine Poorly soluble in aqueous fluid, benzocaine tends to remain at the site of application and is not readily absorbed into the systemic circulation. Because of its low toxic potential, benzocaine is especially useful for anesthesia of large surface area within the oral cavity.

Tetracaine hydrochloride has approximately 10 times the toxicity and potency of procaine. Tetracaine is one of the most effective topical anesthetics, but the drug's toxic potential after surface application should dictate caution in its use.



The FDA has approved four new drugs of dental interest. See the table below.