Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Most alpha-receptor blocking drugs require divided daily administration because of a short plasma half-life. This multicenter study examined the effectiveness and safety of once-daily administration with doxazosin, a quinazoline analog alpha 1-receptor blocking drug with a plasma half-life of 19 hours. Patients with diastolic blood pressure (BP) of 90 to 115 mm Hg entered 4 weeks of single-blind placebo therapy and then were randomized to double-blind treatment with doxazosin (63 patients) or placebo (67 patients). After 10 weeks of titration, standing arterial BP was lowered by 14/11 mm Hg with doxazosin and by 0.5/0.9 mm Hg with placebo (p less than 0.001). Measured hourly for 12 hours after the dose, all standing and supine arterial BP values were significantly lower in the doxazosin group at each hour. Pulse rate increased slightly in both groups int he double-blind phase, but the increase with doxazosin never significantly exceeded that of placebo. Dizziness was the most common complaint with doxazosin, but syncope did not occur. Side effects were mild and transient and did not necessitate withdrawing any participants from the study. Body weight increased by 1.5 kg in the doxazosin group and decreased by 0.2 kg in the placebo group (p less than 0.01). Safe and effective in once-daily administration, doxazosin is suitable for initial therapy in mild and moderate hypertension.
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PMID:Effectiveness of doxazosin in systemic hypertension. 252 70

Doxazosin is a new quinazoline derivative that, like prazosin, has selectivity for alpha 1-receptors. A three-way crossover, randomized, open study in 18 patients with essential hypertension was conducted to investigate the clinical pharmacokinetics of 2, 4, and 8 mg doxazosin at steady state. The pharmacokinetics of the initial 2 mg dose was also studied. Doxazosin showed linear pharmacokinetics. Increases in doses from 2 to 8 mg (steady state) produced proportional increases in doxazosin serum levels (maximum plasma drug concentration [Cmax] minimum plasma drug concentration [C min], and O-24-hour area under the curve [AUC(p-24)], whereas half-life (t1/2) (19.4, 18.7, and 19.7 hours, respectively), volume of distribution (3.4, 3.4, and 3.6 L/kg, respectively), clearance from serum (2.2, 2.2, and 2.1 ml/min/kg, respectively), and degree of protein binding (1.2%, 1.0%, and 1.0% unbound, respectively) were dose independent. Similar t1/2 and time to reach peak concentration (tmax) were obtained with 2 mg initial dose and 2 mg steady state. alpha 1-Acid glycoprotein levels were unchanged during doxazosin treatment. Doxazosin lowered supine and standing systolic and diastolic blood pressure. The blood pressure reduction was associated with an increase in heart rate. Peak hypotensive and tachycardic effects occurred 5.7 +/- 0.1 hours after administration, whereas Cmax was achieved at 2.4 +/- 0.7 hours (tmax). Greater decreases in systolic blood pressure and increases in heart rate were seen in standing than in supine position. The reduction in standing systolic and diastolic blood pressure with 8 mg was greater than with 2 mg (P less than 0.05); however, the increases in heart rate were not different. Dizziness, headaches, and dry mouth were the most frequent side effects. This study indicates that doxazosin shows linear pharmacokinetics between 2 and 8 mg and that because of its long t1/2, once-a-day administration should be adequate for the treatment of hypertension.
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PMID:Clinical pharmacology of doxazosin in patients with essential hypertension. 295 Oct 51

Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic disorders for which there are no medical cures. Clinical sequelae of PV and ET fall into three categories: primary, such as thrombosis and hemorrhage; secondary, resulting from disease progression or treatment. The decision whether to treat the patient is based on the sequelae of no treatment versus short- and long-term toxicities of the three classes of drugs available for treatment: hydroxyurea, interferon-alpha, and anagrelide. Thrombosis is the most common short-term sequelae of untreated disease; the risk increases with age and after the first thrombotic complication. Hydroxyurea, a nonalkylating myelosuppressive agent, is mutagenic and probably leukemogenic over 5 to 15 years, which makes it unsuitable for treating most younger patients. Interferon-alpha, a cytokine that is myelosuppressive and immunomodulatory, has been shown to have a therapeutic effect in both PV and ET. Tolerance to the initial flu-like symptoms of interferon-alpha is usually developed, but dose-limiting symptoms of anorexia, asthenia, and neuropsychiatric disease can occur, along with exacerbation or development of autoimmune diseases. Anagrelide, a quinazoline that inhibits cyclic nucleotide phosphodiesterase, inhibits platelet aggregation and has an idiosyncratic effect of inhibiting megakaryocyte maturation and platelet budding at doses below those that affect platelet function. This agent is a vasodilator with positive inotropic activity and a side-effect profile that may include palpitations, forceful heartbeat, tachycardia, and headache. One in four patients develop fluid retention and/or edema that are controllable with diuretic therapy. Dizziness is frequent, but mild. Because these side effects usually abate in 2 to 4 weeks, successful management of patients taking anagrelide depends on encouraging them to maintain therapy. The availability of these three classes of drugs with differing modes of action suggests that combination therapy may offer the opportunity to achieve better control of proliferation while reducing short-term side effects as well as the risks of dose-related cumulative sequelae.
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PMID:Other secondary sequelae of treatments for myeloproliferative disorders. 1209 54