Antihistamines

Histamine is a potent vasodilator, bronchial smooth muscle constrictor, and stimulant of nocicep-tive itch nerves. In addition to histamine, multiple chemical itch mediators can act as pruritogens on C-fibers, including neuropeptides, prostaglandins, serotonin, acetylcholine, and bradykinin. Human skin mast cells express Hj, H2, and H4 receptors but not H3 receptors. H and H2 receptors are involved in wheal formation and erythema, whereas only H receptor agonists cause pruritus. Complete...

Macrolides

Clarithromycin and azithromycin are used to treat MAC and other nontuberculous mycobacteria. Clarithromycin alters the metabolism of many other drugs that are metabolized by CYPs, leading to many potential drug interactions. The broader pharmacology of these macrolides is presented in Chapter 46. antibacterialactivity and bacterial resistance Clarithromycin is approximately fourfold more active than azithromycin against MAC and is active against most nontuberculous mycobacteria. Azithromycin's...

D6

*Half-life is the approximate elimination (8) half-life (limited data for newer agents). Half-life values given in parentheses are those of active metabolites (commonly W-demethylated) that contribute to overall duration of action. Agents available in slow-release forms that delay absorption but not elimination half-life venlafaxine also inhibits norepinephrine transport at higher doses. *Some serotonin reuptake inhibitors inhibit the hepatic oxidation of other agents potent inhibition is...

Tratment For Vertigo Related To Blood Pressure

*IM, intramuscular injection IV, intravenous administration qd, once a day bid, twice a day tid, three times a day qid, four times a day. *The therapeutic uses are identified as examples to emphasize that most benzodiazepines can be used interchangeably. In general, the therapeutic uses of a given benzodiazepine are related to its half-life and may not match the marketed indications. The issue is addressed more extensively in the text. Half-life of active metabolite may differ. See Appendix II...

R

EFFECTS ON URINARY EXCRETION Osmotic diuretics increase the urinary excretion of nearly all electrolytes, including Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, and phosphate. EFFECTS ON RENAL HEMODYNAMICS Osmotic diuretics increase RBF by a variety of mechanisms, but total GFR usually is little changed. ABSORPTION AND ELIMINATION The oral bioavailability, plasma t1 2, and route of elimination of the available osmotic diuretics are listed in Table 28-3. Glycerin and isosorbide can be given orally mannitol...

Therapeutic Uses

Onchocerciasis Single oral doses of ivermectin (150 pg kg) given every 6-12 months are considered effective, safe, and practical for reducing the number of circulating microfilariae in adults and children 5 years of age or older widespread use of ivermectin is a mainstay of onchocerciasis control programs. Equally important, such therapy reverses lymphadenopathy and acute inflammatory changes in ocular tissues and arrests the progression of ocular pathology. Marked reduction of microfilariae in...

Antispasmodics And Other Agents

Anticholinergic agents (spasmolytics or antispasmodics) often are used in patients with irritable bowel syndrome. The most common agents of this class available in the U.S. are nonspecific antagonists of the muscarinic receptor (see Chapter 7) and include the tertiary amines dicyclomine (bentyl) and hyoscyamine (levsin, others) and the quaternary ammonium compounds glycopyrro-late (robinul) and methscopolamine (famine). The advantage of the latter two compounds is that they have a limited...

Anthelmintic Action

After rapid and reversible uptake, praziquantel has two major effects on adult schistosomes. At low concentrations, it causes increased muscular activity, followed by contraction and spastic paralysis. Affected worms detach from blood vessel walls, resulting in a rapid shift from the mesenteric veins to the liver. At slightly higher concentrations, praziquantel causes tegumental damage, which exposes a number of tegumental antigens. The tegument of schistosomes seems to be the primary site of...

Morphine And Related Opioid Agonists

Morphine is the standard against which newer analgesics are measured. However, responses of an individual patient may vary dramatically with different -opioid receptor agonists. For example, some patients unable to tolerate morphine may have no problems with an equianalgesic dose of methadone, whereas others can tolerate morphine and not methadone. If problems are encountered with one drug, another should be tried. ABSORPTION, DISTRIBUTION, FATE, AND EXCRETION Absorption In general, the opioids...

Effects of Atropine in Relation to Dose

0.5 mg Slight cardiac slowing some dryness of mouth inhibition of sweating 1 mg Definite dryness of mouth thirst acceleration of heart, sometimes preceded 2 mg Rapid heart rate palpitation marked dryness of mouth dilated pupils some 5 mg All the above symptoms marked difficulty in speaking and swallowing restlessness and fatigue headache dry, hot skin difficulty in micturition reduced intestinal peristalsis 10 mg and more Above symptoms more marked pulse rapid and weak iris practically...

Clinical Issues

Abuse of combinations of drugs across pharmacologic categories is common. Alcohol is so widely available that it is combined with practically all other categories. Some combinations reportedly are taken because of their interactive effects. An example is the combination of heroin and cocaine (speedball). Alcohol and cocaine is another very common combination. When confronted with a patient exhibiting signs of overdose or withdrawal, the physician must be aware of these possible combinations...

Xwv

FIGURE 50-4 Structures an mechanism of nonnucleoside reverse transcriptase inhibitors. Pharmacokinetic Properties of Nonnucleoside Reverse Transcriptase Inhibitors* Oral bioavailability, 90-93 50 85 Effect of meals on AUC o Tl7-28 o Plasma t1 2, elim, h 25-30 40-55 2-11 Plasma protein binding, 60 99 98 Metabolism CYP3A4 > CYP2B6 CYP2B6 > CYP3A4 CYP3A4 Renal excretion of parent drug, < 3 < 3 < 5 Autoinduction of Inhibition of CYP3A No Yes Yes ABBREVIATIONS AUC, area under plasma...

Ethyleneimines and Methylmelamines

Altretamine Altretamine (hexalen), formerly known as hexamethylmelamine, is structurally similar to the alkylating agent triethylenemelamine (tretamine), but its precise mechanism of action is unknown. It is used as a palliative treatment for persistent or recurrent ovarian cancer following treatment failure with a cisplatin- or alkylating agent-based combination. The usual dose of altretamine as a single agent in ovarian cancer is 260 mg m2 daily in four divided doses, for 14 or 21 consecutive...

Info

Acetate , 1006 DEPO-TESTOSTERONE testosterone antipsychotics for, 313 biological hypotheses, 278 bipolar forms, 295 clinical presentation, 278 methyldopa and, 550 pharmacotherapy. See also Antidepressants specific agen s in bipolar disease, 296 choice of agent, 295-296 duration of treatment, 296 reserpine and, 553 suicide risk in, 295 DERMABOND cyanoacrylate tissue atopic. See Atopic dermatitis contact. See Contact dermatitis seborrheic. See Seborrheic dermatitis Dermatitis herpetiformis,...

H

TOXICITY, ADVERSE EFFECTS, CONTRAINDICATIONS, DRUG INTERACTIONS Adverse effects unrelated to diuretic efficacy are rare, and most adverse effects are due to abnormalities of fluid and electrolyte balance. Overzealous use of loop diuretics can seriously deplete total-body Na , which may be manifest as hyponatremia and or extracellular fluid volume depletion associated with hypotension, reduced GFR, circulatory collapse, thromboembolic events, and in patients with liver disease, hepatic...

Ca2 Channelantagonists

Ca2 channel antagonists are important drugs for the treatment of hypertension. The pharmacology of these drugs is presented in Chapters 31, 33, and 34. The largest chemical class of calcium-channel blockers is the dihydropyridines amlodipine, felodipine, isradipine, and nifedipine. Diltiazem and verapamil are non-dihydropyridine calcium-channel blockers. All Ca2 channel blockers lower blood pressure by inhibiting Ca2 influx through voltage-sensitive L-type calcium-channels in arte-riolar smooth...