Biomedical subjects

K J McClellan

Publications and source records attributed to K J McClellan.

10 recordsLinked to original sources

PubMed1999

Finasteride: a review of its use in male pattern hair loss.

UNLABELLED: The 5alpha-reductase inhibitor finasteride blocks the conversion of testosterone to dihydrotestosterone (DHT), the androgen responsible for male pattern hair loss (androgenetic alopecia) in genetically predisposed men. Results of phase III clinical studies in 1879 men have shown that oral finasteride 1 mg/day promotes hair growth and prevents further hair loss in a significant proportion of men with male pattern hair loss. Evidence suggests that the improvement in hair count reported after 1 year is maintained during 2 years' treatment. In men with vertex hair loss, global photographs showed improvement in hair growth in 48% of finasteride recipients at 1 year and in 66% at 2 years compared with 7% of placebo recipients at each time point. Furthermore, hair counts in these men showed that 83% of finasteride versus 28% of placebo recipients had no further hair loss compared with baseline after 2 years. The clinical efficacy of oral finasteride has not yet been compared with that of topical minoxidil, the only other drug used clinically in patients with male pattern hair loss. Therapeutic dosages of finasteride are generally well tolerated. In phase III studies, 7.7% of patients receiving finasteride 1 mg/day compared with 7.0% of those receiving placebo reported treatment-related adverse events. The overall incidence of sexual function disorders, comprising decreased libido, ejaculation disorder and erectile dysfunction, was significantly greater in finasteride than placebo recipients (3.8 vs 2.1%). All sexual adverse events were reversed on discontinuation of therapy and many resolved in patients who continued therapy. No other drug-related events were reported with an incidence > or =1% in patients receiving finasteride. Most events were of mild to moderate severity. Oral finasteride is contraindicated in pregnant women because of the risk of hypospadias in male fetuses. CONCLUSIONS: Oral finasteride promotes scalp hair growth and prevents further hair loss in a significant proportion of men with male pattern hair loss. With its generally good tolerability profile, finasteride is a new approach to the management of this condition, for which treatment options are few. Its role relative to topical minoxidil has yet to be determined.

Alopecia↗

PubMed1999

Valsartan/hydrochlorothiazide.

Valsartan/hydrochlorothiazide (HCTZ) combines an angiotensin II AT1 receptor blocker with a thiazide diuretic to produce additive blood pressure reductions without major effects on heart rate. HCTZ did not significantly alter valsartan pharmacokinetics; during combination therapy, HCTZ pharmacokinetics differed from those seen with HCTZ monotherapy. In clinical trials in patients with essential hypertension, adding HCTZ 12.5 or 25 mg/day to valsartan 80 mg/day resulted in a greater blood pressure reduction than increasing the valsartan dosage from 80 to 160 mg/day. The valsartan/HCTZ combination was generally more effective than either drug given alone. Efficacy of the combination was maintained during up to 3 years of treatment. Valsartan/HCTZ was well tolerated in both short and long term trials. The most common adverse events were dizziness, headache and fatigue. The overall incidence of adverse events with the combination was similar to that with placebo. HCTZ-induced hypokalaemia was less common during combination therapy.

Antihypertensive Agents↗

PubMed1998

Midodrine. A review of its therapeutic use in the management of orthostatic hypotension.

Midodrine is a prodrug which undergoes enzymatic hydrolysis to the selective alpha 1-adrenoceptor agonist desglymidodrine after oral administration. Oral midodrine significantly increases 1-minute standing systolic blood pressure compared with placebo. The drug also improves standing time and energy level and clinical symptoms of orthostatic hypotension including dizziness, light-headedness and syncope. Comparative studies have shown midodrine to have similar efficacy to dihydroergotamine mesylate, norfenefrine, fludrocortisone and etilefrine, and to be more effective than dimetofrine and ephedrine in patients with orthostatic hypotension. Midodrine is well tolerated, with the most commonly reported adverse events being piloerection, pruritus, paraesthesias, urinary retention and chills. The risk of supine hypertension, which is associated with midodrine therapy in up to 25% of patients, can be reduced by taking the final daily dose at least 4 hours before bedtime. Thus, oral midodrine is an effective therapeutic option for the management of various forms of orthostatic hypotension. This well-tolerated agent is likely to be useful in conjunction with standard nonpharmacological care.

Adrenergic alpha-Agonists↗

PubMed1998

Transdermal testosterone.

Nightly application of testosterone transdermal (TTD) system to nonscrotal sites in men with hypogonadism results in a 24-hour serum testosterone concentration profile which mimics the circadian pattern observed in healthy young men. The system also normalises dihydrotestosterone/testosterone and estradiol/testosterone ratios and reduces luteinising hormone levels towards the normal range. A multicentre, open-label study demonstrated that nocturnal erectile response and overall sexual function improved during 12 months' treatment with the TTD system (5 mg/day) in men with hypogonadism. Individual variables of sexual desire, arousal, frequency of sexual activity, orgasm and satisfaction also improved. The TTD system is well tolerated, with application site reactions such as pruritus, burn-like blisters and erythema being the most commonly reported events. Prostate-specific antigen levels and prostate volume remain in the normal range during long term treatment.

Administration, Cutaneous↗

PubMed1998

Cerivastatin.

Cerivastatin is a synthetic HMG-CoA reductase inhibitor with high liver selectivity, which lowers plasma cholesterol levels by inhibiting endogenous cholesterol synthesis. In vitro, the affinity of cerivastatin for HMG-CoA reductase was higher than that of lovastatin, simvastatin and pravastatin. This higher enzyme affinity was reflected in vivo, with a lower ED50 (dose causing 50% inhibition) for cerivastatin in rats and beagle dogs compared with lovastatin. Cerivastatin 0.2 mg/day significantly reduced low density lipoprotein (LDL)-cholesterol, total cholesterol and triglyceride levels, and increased high density lipoprotein (HDL)-cholesterol levels, in patients with type IIa hypercholesterolaemia. Available data indicate that cerivastatin has a tolerability profile similar to that of other HMG-CoA reductase inhibitors. No drug interactions were observed when cerivastatin was coadministered with digoxin, warfarin, cimetidine or the antacid magnesium/aluminium hydroxide.

Animals↗

PubMed1998

Eprosartan.

Eprosartan is a nonpeptide angiotensin II receptor antagonist which has a high affinity for the AT1 receptor subtype. When administered at dosages of 400 to 800 mg/day (once or twice daily) for 13 weeks to patients with mild to moderate essential hypertension, eprosartan significantly reduced blood pressure compared with placebo. Eprosartan was at least as effective as enalapril 10 to 40 mg/day in a dose-titration study in patients with severe hypertension. Eprosartan is generally well tolerated; clinical trials have shown the drug to have a tolerability profile similar to that of placebo. As with other angiotensin II receptor antagonists, it does not cause cough. Eprosartan is not metabolised by the cytochrome P450 system and therefore has a low potential for drug interactions.

Acrylates↗

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↗