Biomedical subjects

K J McClellan

Publications and source records attributed to K J McClellan.

23 records · Page 2Linked to original sources

PubMed1998

Levobupivacaine.

Levobupivacaine is an enantiomer of the long-acting local anaesthetic bupivacaine, which, although currently the most widely used agent in surgery and obstetrics, is associated with potentially fatal cardiotoxicity. Levobupivacaine 75 to 122 mg was less arrhythmogenic than the same dose range of bupivacaine in healthy volunteers. Its effects on the corrected QT interval were significantly weaker than those of bupivacaine, and it tended to have a weaker effect on QRS duration. The CNS depressant effect of intravenous levobupivacaine 40 mg was less than that of bupivacaine 40 mg in healthy volunteers, both in terms of the magnitude of the effect and the regions of the cortex affected. Clinical studies have demonstrated that epidural levobupivacaine produces a sensory and motor block clinically similar to that of bupivacaine in patients requiring anaesthesia during surgery. However, the duration of sensory block was significantly longer with levobupivacaine 0.75% than with levobupivacaine 0.5% or bupivacaine 0.5% or 0.75% in one study. Levobupivacaine 0.25% was as effective as bupivacaine 0.25% in women requiring epidural anaesthesia during labour with respect to time to onset of pain relief, overall quality of analgesia, extent of sensory blockade and number of patients reporting motor block. Levobupivacaine is as well tolerated as bupivacaine. In a clinical study involving 88 patients who received either drug, intraoperative hypotension was the most commonly reported adverse event with levobupivacaine and no serious arrhythmias occurred.

Anesthetics, Local↗

PubMed1998

Candesartan cilexetil. A review of its use in essential hypertension.

UNLABELLED: Candesartan cilexetil is completely converted to the nonpeptide angiotensin II receptor blocker candesartan during absorption from the gastrointestinal tract. Candesartan selectively blocks and dissociates slowly from the angiotensin II subtype 1 (AT1) receptor which mediates most of the known activities of angiotensin II. When administered once daily, oral candesartan cilexetil 8 to 32 mg dose-dependently and effectively reduces blood pressure in patients with mild to moderate essential hypertension. In comparative studies, candesartan cilexetil 8 mg/day was as effective as usual therapeutic dosages of enalapril, losartan potassium, hydrochlorothiazide and amlodipine. One study showed candesartan cilexetil 16 mg/day to be more effective than losartan potassium 50 mg/day. Furthermore, the combination of candesartan cilexetil with either hydrochlorothiazide or amlodipine resulted in additive antihypertensive effects. Preliminary evidence suggests that the blood pressure-lowering effects of candesartan cilexetil are associated with the prevention or improvement of end-organ damage in patients with hypertension. However, this requires further confirmation in clinical studies. Candesartan cilexetil improves insulin sensitivity in patients with hypertension and does not affect glucose homeostasis or the serum lipid profile in those with coexisting type 2 (non-insulin-dependent) diabetes mellitus. Candesartan cilexetil is well tolerated in patients with hypertension. Pooled data indicate that the tolerability profile of the drug is not significantly different from that of placebo, with headache being the most commonly reported event. Adverse events are not dose related and are mostly mild to moderate in severity. Candesartan cilexetil is better tolerated than enalapril, primarily because of a reduced incidence of cough, and was not associated with the hypokalaemia or hyperuricaemia seen with hydrochlorothiazide in a study in patients aged > or = 75 years. The drug has an adverse events profile similar to that of losartan potassium in patients with mild to moderate hypertension. CONCLUSIONS: once daily candesartan cilexetil is effective and well tolerated when used once daily (as monotherapy or in combination with other antihypertensive agents) in patients with mild, moderate or severe hypertension. Initially, however, the drug is likely to be used as an alternative to other agents in patients not responding to or intolerant of their current drug therapy.

Aged↗

PubMed1998

Telmisartan.

Telmisartan is a nonpeptide angiotensin II receptor antagonist which selectively and insurmountably inhibits the angiotensin II AT1 receptor subtype without affecting other receptor systems involved in cardiovascular regulation. Oral telmisartan dose-dependently reduced blood pressure (BP) in various animal models of hypertension. In transgenic rats, telmisartan reduced cardiac hypertrophy and glomerulosclerosis. When administered at dosages of 40 to 160 mg once daily to patients with mild to moderate hypertension, telmisartan significantly reduced systolic and diastolic BP compared with placebo and was at least as effective as atenolol 50 or 100 mg and lisinopril 10 to 40 mg. One study showed telmisartan 80 mg/day to be more effective than enalapril 20 mg/day. In 2 studies that used ambulatory BP monitoring, once daily telmisartan provided better control of diastolic BP for the full dosing interval than losartan potassium 50 mg or amlodipine 5 or 10 mg. In a single study in patients with severe hypertension, a telmisartan-based regimen had antihypertensive efficacy similar to that of an enalapril-based regimen. Telmisartan had a tolerability profile similar to that of placebo in clinical studies.

Angiotensin Receptor Antagonists↗

PubMed1998

Tirofiban. A review of its use in acute coronary syndromes.

UNLABELLED: Tirofiban is an intravenously administered nonpeptide glycoprotein IIb/IIIa receptor antagonist which specifically inhibits fibrinogen-dependent platelet aggregation and prolongs bleeding times in patients with acute coronary syndromes. Adenosine diphosphate (ADP)-induced platelet aggregation returns to near-baseline levels within 4 to 8 hours after cessation of a tirofiban infusion, a finding consistent with the drug's elimination half-life of approximately 2 hours. Three large clinical trials have shown that, when administered with a standard heparin and aspirin regimen, tirofiban reduces the risk of ischaemic complications in patients with unstable angina/non-Q-wave myocardial infarction (MI) and in patients undergoing percutaneous revascularisation. In PRISM-PLUS, a study involving 1915 patients with unstable angina/non-Q-wave MI, administration of intravenous tirofiban (0.4 microgram/kg/min loading dose for 30 minutes followed by a 0.10 microgram/kg/min infusion) with heparin for at least 48 (mean 71.3) hours reduced the 7-day risk of the composite end-point of MI, death and refractory ischaemia by 32% compared with heparin alone. The between-group risk reduction remained significant at 30 days (22%) and 6 months (19%). Similarly, in high-risk patients undergoing coronary angioplasty in RESTORE, the addition of tirofiban (10 micrograms/kg bolus in the 3 minutes prior to intervention followed by 0.15 microgram/kg/min for 36 hours) to a standard heparin regimen significantly reduced the risk of ischaemic complications by 38% on day 2 and 27% on day 7 compared with heparin alone. Although interim analysis in PRISM-PLUS showed that the use of tirofiban without heparin increased the 7-day risk of death compared with heparin alone, this finding was inconsistent with the effects of tirofiban on the risk of death in PRISM, a study involving 3232 patients with unstable angina/non-Q-wave MI. Tirofiban is generally well tolerated. Bleeding complications were the most commonly reported events associated with tirofiban in clinical trials, but the rate of major bleeding in tirofiban recipients was not significantly different from that reported with heparin. Thrombocytopenia (platelet count < 90,000 cells/microliter) occurred slightly more frequently with tirofiban (with or without heparin) than with heparin alone. CONCLUSIONS: Tirofiban reduces the risk of ischaemic complications in patients with unstable angina/non-Q-wave MI and high-risk patients undergoing revascularisation when used against a background of heparin and aspirin. Furthermore, the drug has an acceptable tolerability profile. Therefore, intravenous tirofiban is likely to be used as an adjunct to heparin and aspirin in patients with acute coronary syndromes including high-risk patients undergoing revascularisation.

Acute Disease↗

PubMedDate not supplied

Topical metronidazole. A review of its use in rosacea.

UNLABELLED: Topical application of the antibacterial agent metronidazole is effective in the treatment of moderate to severe rosacea, although its mechanism of action has yet to be clearly established. Metronidazole preparations (0.75 and 1% cream, 0.75% gel and 0.75% lotion) were significantly more effective than placebo in patients with moderate to severe rosacea when administered to the affected area once or twice daily for 7 to 12 weeks. The mean number of papules and pustules decreased by between 48 and 65.1% during the treatment period. Reductions were fairly consistent regardless of formulation, strength or application frequency and were significant compared with placebo (p < 0.05). In 1 study, most of the overall effects of metronidazole were observed within the first 3 weeks. Although data are limited, topical metronidazole appears to improve inflammatory lesions and erythema as effectively as oral tetracyclines. Like tetracyclines, however, metronidazole has no effect on telangiectasia. Metronidazole 0.75% gel seems to be effective in maintaining remission of rosacea symptoms in patients successfully treated with both oral tetracycline and topical metronidazole. In the only study, 77% of patients treated with metronidazole gel compared with 58% of placebo recipients (p < 0.05) remained in remission 6 months after the tetracycline was stopped. The effects of topical metronidazole preparations on rosacea symptoms are palliative, not curative, but preliminary data suggest that relapse rates after cessation of therapy are no worse than those after cessation of oral oxytetracycline. Topical metronidazole formulations are generally well tolerated locally, with stinging, dryness, burning and itching reported in < or = 2% of patients. Because minimal concentrations of metronidazole are absorbed after topical administration, systemic adverse events and drug interactions seen with oral or intravenous metronidazole are unlikely. CONCLUSIONS: Topical metronidazole formulations are significantly more effective than placebo when used in the initial treatment of patients with moderate to severe rosacea. Furthermore, limited evidence suggests that the use of topical metronidazole alone may be as effective as oral tetracyclines against the disorder's inflammatory component. Therefore, for those patients with a preference for topical rather than oral therapy, the use of a topical metronidazole formulation must be a consideration.

Administration, Topical↗