Anesthetics local, combinations

There are many pharmaceutical products widely used in medicine and dentistry that contain phenol, sometimes in fairly high concentrations. Bonain s local anesthetic mixture, combining menthol, cocaine and phenol, is well known, and is used, for example, as an intranasal analgesic treatment for certain facial pains. Other products containing phenol include hemorrhoid creams, chilblain solutions, ear drops or wax remover drops, psoriasis treatments, and mouth sprays with phenol in concentrations ranging from 3 mg/ml to 50 mg/g. Applying these products locally introduces only a small quantity of phenol into the organism at well-spaced intervals, and does not appear to cause intoxication. 

The major clinical use of hyaluronidase is in ophthalmology, by improving the local anesthetic infiltration [128, 129], The anesthetic-hyaluronidase combinations has also found applications in pain relief for high ligations in varicose vein surgery or hernia surgery [130], Clinically, the enzyme is used in chemotherapy to enhance the antineoplastic activity of cytostatics and in the treatment of acute myocardial infarction [131],... 

The effects of the common practice of injecting local anesthetics in combination with methylprednisolone have been investigated in vitro [12 ]. Chondrocyte viability fell significantly with increasing doses and time of exposure to clinically relevant doses. 

These agents are often combined with a vasoconstrictant such as epinephrine [51-43-4]. By using such a combination, the local anesthetic is held in the area for a longer period of time and its effect extended hemorrhage is minimized, blood loss prevented, and a better surgical repair obtained. 

Seizure threshold Promethazine may lower the seizure threshold consider this when giving to people with known seizure disorders or when giving in combination with narcotics or local anesthetics that also may affect seizure threshold. 

Pramocaine is a topical anesthetic used as an antipruritic. The use on large areas and mucous membranes should be avoided. Topical lidocaine in combination with levomenthol is used for the same indications. Levomenthol has mild local anaesthetic, cooling and decongestant properties. 

Dextromethorphan hydrobromide is the D-isomer of levorphanol. It lacks CNS activity but acts at the cough center in the medulla to produce an antitussive effect. It is half as potent as codeine as an antitussive. Anecdotal reports of abuse exist, but studies of abuse potential are lacking. It has few side effects but does potentiate the activity of monoamine oxidase inhibitors, leading to hypotension and infrequently coma. Dextromethorphan is often combined in lozenges with the local anesthetic benzocaine, which blocks pain from throat irritation due to coughing. 

The basic components in the structure of local anesthetics are the lipophilic aromatic portion (a benzene ring), an intermediate chain, and the hydrophilic amine portion (Fig. 27.1). The intermediate chain has either an ester linkage from the combination of an aromatic acid and an amino alcohol or an amide linkage from the combination of an aromatic amine and an amino acid. The commonly used local anesthetics can be classified as esters or amides based on the structure of this intermediate chain. 

Local anesthetics are used extensively on the mucous membranes in the nose, mouth, tracheobronchial tree, and urethra. The vasoconstriction produced by some local anesthetics, cocaine especially, adds a very important advantage to their use in the nose by preventing bleeding and inducing tissue shrinkage. Topical anesthesia permits many diagnostic procedures in the awake patient, and when it is combined with infiltration techniques, excellent anesthesia may be obtained for many... 

Frequently vasoconstrictors are combined with local anesthetics to delay absorption of the anesthetic from its injection site. What is the most widely employed agent ... 

Answer Bupivacaine use for local anesthesia of this type is very safe and commonly done. However, SOMETIMES inadvertent vascular injection results in a large amount of anesthetic in the systemic circulation. Because the heart is beating, the excitable tissue in the heart is being depolarized repetitively. Local anesthetics bind to rapidly depolarizing tissues more than tissues at rest (frequency-dependent block). Also, bupivacaine has a long duration of action because of its long residence time at receptors (sodium channel). Thus, this combination of factors contributed to the catastrophic outcome of this case. Had the same case involved lidocaine, the resuscitation would have likely been successful. 

Combining agonists with some local anesthetics greatly prolongs the duration of infiltration nerve block the total dose of local anesthetic (and the probability of toxicity) can therefore be reduced. Epinephrine, 1 200,000, is the favored agent for this application, but norepinephrine, phenylephrine, and other agonists have also been used. Systemic effects on the heart and peripheral vasculature may occur even with local drug administration but are usually minimal. 

Recovery is sufficiently rapid with most intravenous drugs to permit their use for short ambulatory (outpatient) surgical procedures. In the case of propofol, recovery times are similar to those seen with sevoflurane and desflurane. Although most intravenous anesthetics lack antinociceptive (analgesic) properties, their potency is adequate for short superficial surgical procedures when combined with nitrous oxide or local anesthetics, or both. Adjunctive use of potent opioids (eg, fentanyl, sufentanil or remifentanil see Chapter 31) contributes to improved cardiovascular stability, enhanced sedation, and perioperative analgesia. However, opioid compounds also enhance the ventilatory depressant effects of the intravenous agents and increase postoperative emesis. Benzodiazepines (eg, midazolam, diazepam) have a slower onset and slower recovery than the barbiturates or propofol and are rarely used for induction of anesthesia. However, preanesthetic administration of benzodiazepines (eg, midazolam) can be used to provide anxiolysis, sedation, and amnesia when used as part of an inhalational, intravenous, or balanced anesthetic technique. 

Since local anesthetics have membrane-stabilizing effects, both parenteral (eg, intravenous lidocaine) and oral (eg, mexiletine, tocainide) formulations of local anesthetics have been used to treat patients with neuropathic pain syndromes because these syndromes are thought to involve uncontrolled, rapid, sensory fiber firing. Systemic local anesthetic drugs are commonly used as adjuvants to the combination of a tricyclic antidepressant (eg, amitriptyline) and an anticonvulsant (eg, carbamazepine) in chronic pain patients who fail to respond to the combination of antidepressant and anticonvulsant. 

Pramoxine hydrochloride is a topical anesthetic that can provide temporary relief from pruritus associated with mild eczematous dermatoses. Pramoxine is available as a 1% cream, lotion, or gel and in combination with hydrocortisone acetate. Application to the affected area two to four times daily may provide short-term relief of pruritus. Local adverse effects include transient burning and stinging. Care should be exercised to avoid contact with the eyes. 

Lidocaine (synonyme lignocaine) was introduced as the first amide in 1944 and is the most commonly used LA today. It has a rapid onset of action with intermediate duration and an intermediate toxicity. The maximum tolerated dose with infiltration or injection is 200 mg (500 mg when combined with adrenaline). Lidocaine is dealkylated in the liver to monoethylglycine xylidide and glycine xylidide which retain local anesthetic activity. It is available in a variety of preparations including creams, gels, patches and solutions, often in combination with adrenaline. 

In scalp-reduction surgery, hyaluronidase lias been combined with die local anesthetics to facilitate their diffusion, to enhance the anesthesia, and to ease the dissection [124]. 

There are many types of steroid hormones in the body, such as the sex/gonadal hormones testosterone and estrogen, thyroid hormones, growth hormones, and stress hormones, which serve various normal functions. One type of steroid— corticosteroids or glucocorticoids—is secreted by the adrenal glands (located just above the kidneys). These steroids, particularly synthetic versions of them, have powerful antiinflammatory actions that help to relieve pain. They are often given as an epidural injection to relieve neck or back pain that results from a compressed or pinched nerve. They can also be injected directly into a joint to relieve pain caused by inflammation in conditions such as tendonitis (inflammation of the tendons), carpal tunnel syndrome, tennis elbow, bursitis (inflammation of sac-like cavities in tendons or muscles that allow them to slide easily over bone), or other joint pain. Professional athletes, who routinely experience one or more of these conditions, are often given local steroid injections. Frequently, the steroid is combined with a local anesthetic such as lidocaine. 

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