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Biomedical subjects

R N Brogden

Publications and source records attributed to R N Brogden.

At least 127 records · Page 7Linked to original sources

Piretanide. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy.

Piretanide is a potent 'loop' diuretic whose principal site of action is in the thick ascending limb of the loop of Henle. When administered orally or intravenously to healthy volunteers it rapidly increases diuresis and electrolyte excretion, and the effects are short-lived. In comparative studies, piretanide has generally been found to be 5 to 7 times more potent than frusemide (furosemide) but only one-tenth as potent as bumetanide, on a weight-for-weight basis. Piretanide 6 to 12 mg/day, in conventional or sustained release formulations, has been shown to significantly lower elevated blood pressure in a large proportion of patients with mild to moderate hypertension. Comparative trials of up to 3 months duration indicate that at this dosage piretanide is of comparable antihypertensive efficacy as hydrochlorothiazide 50 to 100 mg/day, but has significantly less effect on serum potassium levels. Short term studies in patients with oedema caused by renal, hepatic or cardiac failure demonstrated that piretanide 6 to 9 mg is of similar diuretic potency as frusemide 40 mg and bumetanide 1 mg. In medium term trials in patients with congestive heart failure piretanide 6 mg/day produced equivalent symptomatic improvement as frusemide 40 mg/day. When used to treat oedema caused by liver disease, piretanide 12 to 24 mg/day was successful in only about 50% of patients, but spironolactone added to the treatment regimen greatly increased the response rate. Generally, piretanide has been well-tolerated in clinical trials, although the conventional tablet formulation has caused a relatively high incidence of acute adverse effects--these were greatly reduced with the introduction of the sustained release formulation. Serum concentrations of most electrolytes have not shown any consistent adverse trends and hyperuricaemia and hypokalaemia have been encountered infrequently. Thus, piretanide appears to offer an effective alternative to other 'loop' diuretics for the treatment of oedematous diseases and to hydrochlorothiazide for the management of mild to moderate hypertension. However, its relative place in therapy remains to be clarified with wider clinical experience.

Angina Pectoris↗

Pirbuterol. A preliminary review of its pharmacological properties and therapeutic efficacy in reversible bronchospastic disease.

Pirbuterol is a beta-adrenoceptor agonist which differs structurally from salbutamol in the substitution of a pyridine ring for the benzene ring. In common with salbutamol, pirbuterol demonstrates both bronchodilatory and cardiovascular effects. Generally, improvements of up to 25% are noted in forced expiratory volume in 1 second (FEV1) [versus baseline or placebo] in asthmatic patients treated with pirbuterol for several months. In individual 12-week double-blind comparative studies, pirbuterol aerosol appeared similar to orciprenaline (metaproterenol) aerosol, and orally administered pirbuterol appeared similar to orally administered salbutamol in bronchodilator efficacy. However, well-designed long term comparative studies are needed to more clearly define the comparative efficacy of pirbuterol and alternative beta-adrenoceptor agonists.

Adrenergic beta-Agonists↗

Guanadrel. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic use in hypertension.

Guanadrel sulphate is an orally active peripheral sympathetic inhibitor (adrenergic neuron-blocking drug). In comparative studies, guanadrel was comparable in efficacy with guanethidine or methyldopa in mild to moderately severe hypertension, although generally it caused fewer central nervous system side effects than methyldopa and less orthostatic dizziness and diarrhoea than guanethidine. However, its efficacy in patients whose blood pressure remains inadequately controlled by other drugs (except diuretics alone) has yet to be adequately demonstrated. Guanadrel has a rapid onset of action and a half-life of about 10 hours, thus dose titration can be achieved more rapidly than with guanethidine, and twice daily administration is appropriate. Generally, guanadrel has been well tolerated, withdrawal of treatment due to adverse effects seldom being necessary. Thus, guanadrel appears to be a suitable alternative to methyldopa for the treatment of mild to moderately severe hypertension not controlled adequately by diuretics alone.

Antihypertensive Agents↗

Pirenzepine. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy in peptic ulcer disease and other allied diseases.

Pirenzepine is a 'selective' antimuscarinic agent which, unlike classic anticholinergic agents, inhibits gastric acid secretion at lower doses than are required to affect gastrointestinal motility, salivary, central nervous system, cardiovascular, ocular and urinary functions. On a weight basis, pirenzepine has one-tenth to one-eighth the potency of atropine in inhibiting stimulated gastric acid secretion in humans. Extensive controlled trials utilising endoscopy in outpatients with duodenal ulcers indicate that patient response to pirenzepine is dose related. Doses of 100 to 150 mg/day are superior to placebo in promoting duodenal ulcer healing and in diminishing day and night pain and supplementary antacid consumption. At such doses, the efficacy of pirenzepine appears to be superior to that of gefarnate 300 mg/day and generally not significantly different from that of cimetidine 1 g/day in treating duodenal ulcers. A beneficial effect of pirenzepine in the prevention of duodenal ulcer recurrence was apparent in preliminary studies in small numbers of patients, but its efficacy in this regard needs further confirmation and the optimum dosage determined. Less extensive data on the treatment of benign gastric ulcers suggest that pirenzepine 100 to 150 mg/day is superior to placebo and gefarnate 300 mg/day and does not differ significantly from cimetidine 1 g/day promoting gastric ulcer healing. Pirenzepine is well tolerated by most patients, with a low incidence of typical antimuscarinic effects on the gastrointestinal tract, genitourinary system or heart being reported in clinical studies. However, dry mouth and blurred vision are the more common side effects with clinically effective doses. Thus, pirenzepine appears to have relatively selective antimuscarinic activity, although controlled studies comparing pirenzepine and conventional antimuscarinics in patients with peptic ulcer disease have not been reported.

Benzodiazepinones↗

Xipamide. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy.

Xipamide is a diuretic derived from salicylic acid and has a structural resemblance to chlorthalidone. Its pharmacodynamic profile shows a diuretic efficacy is similar to that of frusemide (furosemide) at doses up to 40 mg, but the onset and duration of action are comparable to those of hydrochlorothiazide. Xipamide has been studied mostly in the treatment of mild to moderate essential hypertension, with few controlled studies of its use in oedematous states. The efficacy of xipamide 20 to 40 mg once daily in patients with mild to moderate hypertension is comparable to that of bendrofluazide 5 mg, bumetanide 1 mg or hydrochlorothiazide 50 mg when used alone in newly treated or previously treated patients. The addition of xipamide 20 to 40 mg daily to regimens containing beta-blockers, adrenergic neuron-blocking drugs and/or methyldopa has resulted in a further reduction in blood pressure. A few studies in oedematous states suggest that xipamide 40 to 80 mg is comparable in efficacy to equal doses of frusemide, and that the side effects of hypokalaemia, hyperuricaemia and increased blood glucose in diabetics or latent diabetics are similar to those of other diuretics. Thus, xipamide is a suitable alternative to other diuretics in the treatment of mild to moderate hypertension and combines the efficacy of frusemide with a less abrupt action in the treatment of oedema.

Animals↗

Norfloxacin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use.

Norfloxacin is one of the new 4-quinolone antibacterial agents. A fluorinated piperazinyl-substituted congener of nalidixic acid, it demonstrates a much wider in vitro antibacterial spectrum and greater potency than the parent compound. Its antibacterial activity against most Gram-negative pathogens is enhanced in comparison to nalidixic acid, but is similar to that of some of the other new 4-quinolones like enoxacin, and slightly less than that of ciprofloxacin. Unlike nalidixic acid, norfloxacin is also active against Pseudomonas aeruginosa and some Gram-positive organisms. In acute or uncomplicated urinary tract infections, norfloxacin has repeatedly been shown to be as effective as co-trimoxazole. Single studies have demonstrated a significantly better bacteriological cure rate with norfloxacin than with pipemidic acid, and similar cure rates with norfloxacin and both a nalidixic acid/sodium citrate mixture and amoxycillin. Similar results were found in a few studies comparing norfloxacin to pipemidic acid or amoxycillin in patients with chronic and/or complicated urinary tract infections. Norfloxacin is as effective as spectinomycin in gonorrhoea due to penicillin-resistant N. gonorrhoeae, and cures bacterial gastroenteritis caused by several gastrointestinal pathogens. Norfloxacin appears to be well tolerated and may have a low propensity to select for bacterial resistance during clinical use, although the latter needs further confirmation.

Antifungal Agents↗

Flunarizine. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic use.

Flunarizine is a 'selective' calcium entry blocker with a similar chemical structure and pharmacological profile to the related compound, cinnarizine. However, in contrast to cinnarizine it has a long plasma half-life and need only be given once a day. The majority of therapeutic trials in the prophylaxis of migraine, occlusive peripheral vascular disease and vertigo of central or peripheral origin have been placebo-controlled, and have shown that the drug produces significantly greater beneficial effects than placebo as evaluated by subjective and objective criteria. A small number of comparative studies have shown flunarizine to be at least as effective as pizotifen in migraine prophylaxis, and in a longer term study as effective as cinnarizine in vertigo of central origin. However, it has not been compared with other drugs which may be useful in these areas, such as methysergide in migraine prophylaxis, some antihistamines or phenothiazines in vertigo, or (understandably at this stage of its evolution) with surgical revascularisation in severe occlusive peripheral vascular disease. In preliminary placebo-controlled studies there was some evidence that flunarizine may improve impaired cognitive function in patients with cerebrovascular disorders, but such findings need further confirmation in additional carefully conducted studies. With a very long half-life, flunarizine may be given once daily; and drowsiness, the main side effect, can be minimised by taking the daily dose in the evening. Thus, it appears that flunarizine will offer a useful alternative in some therapeutic areas that can be difficult to manage with previously available therapy. However, a definitive statement on its relative place in therapy of such conditions must await a few well-controlled comparative studies.

Adult↗

Intravenous glyceryl trinitrate (nitroglycerin). A review of its pharmacological properties and therapeutic efficacy.

The recently introduced preparation of intravenous glyceryl trinitrate (nitroglycerin) provides a rapid steady therapeutic blood concentration of nitrates during continuous infusion. Intravenous glyceryl trinitrate causes venodilation at low doses, but at higher doses dilates both arteries and veins. Its principal haemodynamic effects at therapeutic dosages include a decrease in blood pressure in preload (left ventricular filling pressure) and in determinants of afterload, and a decrease in myocardial oxygen demand. Human pharmacokinetic data are few and difficult to interpret due to wide interstudy and interindividual variation. There is no close correlation between infusion rate, blood concentration and haemodynamic effects. The nature of the patient population treated with intravenous glyceryl trinitrate has largely precluded the use of a placebo, but in open trials the drug has been used successfully in the treatment of unstable angina, left ventricular failure accompanying acute myocardial infarction and in the control of hypertension associated with cardiac surgery at dosages titrated to achieve a specific end-point. Favourable haemodynamic responses have been achieved in very short term studies in congestive heart failure, and preliminary studies suggest that institution of intravenous glyceryl trinitrate early after acute myocardial infarction may limit ischaemic damage. However, use of the drug in acute myocardial infarction remains controversial. Intravenous glyceryl trinitrate is generally well tolerated, although hypotension and headache occur occasionally, and sinus tachycardia and bradycardia less frequently. Careful titration of dosage is required (beginning at 5 micrograms/min), and if the infusion sets contain polyvinylchloride, the delivered dose is lower than that calculated, because of adsorption of glyceryl trinitrate onto the plastic tubing.

Acute Disease↗

Ursodeoxycholic acid: a review of its pharmacological properties and therapeutic efficacy.

Ursodeoxycholic acid is the 7 beta-hydroxy epimer of chenodeoxycholic acid and is normally present in only trace amounts in the bile. Oral administration of pharmacological doses markedly decreases biliary cholesterol saturation. Complete or partial dissolution of radiolucent gallstones located in a functioning gallbladder occurred in about 40 to 55% of patients treated with ursodeoxycholic acid in controlled studies of 6 months duration. Patients showing partial gallstone dissolution at that time are likely to continue improving possibly to complete gallstone dissolution with continued therapy. The success rate with ursodeoxycholic acid may be increased top about 80% if more stringent patient selection criteria are applied to include only those with non-calcified floating cholesterol stones of less than 10 to 15 mm diameter. Those with calcified stones or stones greater than 15 mm diameter or unlikely to respond to ursodeoxycholic acid therapy. The optimal dose in published studies was about 8 to 10 mg/kg/day, which is about half to two-thirds the dose of chenodeoxycholic acid (15 mg/kg/day) achieving approximately equivalent results. Ursodeoxycholic acid appears to be remarkably well tolerated, with diarrhoea occurring in only a very small proportion of patients. While surgery is clearly the preferred treatment in many patients with symptomatic gallstones, in a carefully selected subgroup of such patients gallstone dissolution therapy with ursodeoxycholic acid offers an important and worthwhile alternative.

Animals↗

Alprazolam: a review of its pharmacodynamic properties and efficacy in the treatment of anxiety and depression.

Alprazolam is a triazolobenzodiazepine which is related to diazepam and other 1,4-benzodiazepines, and has a similar pharmacological profile. Relative to the newer benzodiazepines, alprazolam has an intermediate half-life of 10 to 12 hours in healthy young subjects. In placebo-controlled and double-blind comparative trials in patients with anxiety, alprazolam was of comparable efficacy to diazepam and generally caused a lower incidence of drowsiness. Alprazolam has antidepressant activity and has been shown to be similar in efficacy to imipramine in the treatment of unipolar depression. Thus, alprazolam may be particularly useful in patients with mixed anxiety/depression. However, its general acceptance as an antidepressant awaits further studies.

Alprazolam↗

Sucralfate. A review of its pharmacodynamic properties and therapeutic use in peptic ulcer disease.

Sucralfate is a basic aluminium salt of sulphated sucrose which is advocated for use in peptic ulcer disease. It is minimally absorbed after oral administration and is believed to act primarily at the ulcer site by protecting the ulcer from the effects of pepsin, acid and possibly bile salts. Controlled therapeutic trials have demonstrated that sucralfate 1g 4 times daily is effective in increasing the rate of healing of duodenal and gastric ulcer over a period of 4 to 8 weeks. Trials comparing sucralfate and cimetidine have not found any significant difference in efficacy between the drugs in small numbers of patients. A dosage of 2g daily given prophylactically decreases the rate of recurrence of duodenal ulcers, but the efficacy of sucralfate in preventing relapse of gastric ulcers has yet to be clearly demonstrated. Sucralfate is particularly well tolerated. Constipation, the most common side effect, occurs in 2% of patients. Thus, sucralfate offers an effective and well tolerated alternative for the management of peptic ulcer disease.

Aluminum↗

Oxatomide. A review of its pharmacodynamic properties and therapeutic efficacy.

Oxatomide is an orally active H1-histamine receptor antagonist which, as appears to occur with some other antihistamines, also inhibits mast cell degranulation. Oxatomide has demonstrated response rates similar to those with other more established members of its drug class in a few studies of chronic urticaria and allergic rhinitis. Interestingly, some patients responding to oxatomide were said to be unresponsive to previously administered antihistamines. The effect of oxatomide was little different from placebo in clinical trials of bronchial asthma in adults. While somewhat more encouraging results have been reported in children with bronchial asthma when higher than presently recommended dosages were employed, and in follicular conjunctivitis, atopic dermatitis and food allergy, reports to date are largely preliminary in nature and additional well-controlled studies are needed to clarify the efficacy of oxatomide in such conditions. The drug has been generally well tolerated, but shares some of the familiar H1-histamine receptor antagonist side effects. As with other similarly acting drugs, the 2 primary side effects with oxatomide are drowsiness and weight gain. Thus, on the basis of present evidence, a trial with oxatomide seems a potentially useful alternative in patients with conditions known or thought to be allergic in nature, in whom more established treatments were ineffective or poorly tolerated.

Animals↗

Lorcainide. A preliminary review of its pharmacodynamic properties and therapeutic efficacy.

Lorcainide is a type I antiarrhythmic drug of the local anesthetic type. It can be given either intravenously or orally, and its pharmacokinetic properties allow relatively long (12 hours) dosing intervals with oral administration. A slowly eliminated metabolite, norlorcainide, probably contributes to the effects of orally administered lorcainide in chronically treated patients. In mainly short term studies, lorcainide has been shown to suppress ventricular ectopy in about 80% of patients treated either orally or intravenously. Preliminary evidence suggests that its efficacy in suppressing ectopy in the setting of acute myocardial infarction is comparable with that of lignocaine (lidocaine). It is of variable efficacy in preventing recurrent ventricular tachycardia and has been shown to be effective in some patients who have failed to respond to other antiarrhythmic drugs. Experience is limited in treating supraventricular arrhythmia, but initial results in patients with Wolff-Parkinson-White syndrome have been favourable. Adverse cardiac effects are infrequent. Abnormal sinus node function may be exacerbated by lorcainide treatment, however, and bundle branch block may be precipitated in patients with pre-existing conduction system disease. Exacerbation of pre-existing arrhythmias is uncommon, and clinically important myocardial depression has not been observed. The most frequent side effect is disturbed sleep during the initiation of oral treatment, which may occur in the majority of patients but usually responds to treatment with a benzodiazepine and subsides with time. Thus, lorcainide appears useful against a variety of arrhythmias. With its convenient dosage schedule and apparently low incidence of serious side effects it should become a useful addition to the antiarrhythmic agents available, although longer term studies are needed to confirm its continued efficacy and lack of unexpected side effects when used for long periods.

Animals↗

Gliclazide. A preliminary review of its pharmacodynamic properties and therapeutic efficacy in diabetes mellitus.

Gliclazide is a 'second generation' oral hypoglycaemic agent. The particular interest with this drug is that it has shown certain effects on the blood for which it is hoped there may be some clinical benefit in diabetic angiopathies. Both in animal and human studies it has demonstrated a reduction in platelet adhesiveness and aggregation, whilst possible enhancement of platelet metabolism, reduction of coagulant factors, as well as increased fibrinolytic activity, are still being investigated. Initial trials have suggested that gliclazide therapy may reverse or at least slow down the progression of diabetic retinopathy. However, a few additional well-designed long term controlled studies are needed to confirm these findings, and to clarify whether any beneficial effect on diabetic retinopathy is unique to gliclazide or also occurs with other oral hypoglycaemic drugs. Both newly diagnosed maturity onset diabetics as well as those previously treated with sulphonylureas respond well to gliclazide therapy. In the small comparative studies which have been reported, gliclazide was of comparable efficacy to other oral hypoglycaemic agents.

Absorption↗

Auranofin. A preliminary review of its pharmacological properties and therapeutic use in rheumatoid arthritis.

Auranofin is the first orally active gold compound for the treatment of rheumatoid arthritis. Like other chrysotherapeutic agents, its exact mechanism of action is unknown, but it probably acts via immunological mechanisms and alteration of lysosomal enzyme activity. Although long term clinical experience with auranofin is limited, its efficacy appears to approach that of sodium aurothiomalate. Further comparative studies with aurothioglucose, hydroxychloroquine and D-penicillamine are required before definitive statements can be made regarding the relative efficacy of auranofin and these agents. While patients have demonstrated clinical remission of rheumatoid arthritis in response to auranofin therapy, radiological studies have been inconclusive regarding its effect on the occurrence or progression of erosive lesions. Auranofin is relatively well tolerated in most patients, but diarrhoea, skin rash, and pruritus are sometimes troublesome, and thrombocytopenia and proteinuria are potentially serious side effects which may occur during therapy. Whereas mucocutaneous side effects are more frequent with injectable gold compounds, gastrointestinal reactions are the most common adverse effect seen with auranofin. The frequency of side effects has been similar with auranofin and sodium aurothiomalate, but they are generally less severe with auranofin. While some of the side effects are controlled by a reduction in dosage, temporary or permanent withdrawal of auranofin may be necessary. Auranofin is clearly a useful addition to the limited list of agents with disease-modifying potential presently available for the treatment of rheumatoid arthritis. It will doubtless generate much interest as its final place in therapy becomes better defined through additional well-designed studies and wider clinical experience.

Absorption↗

Ceftriaxone. A review of its antibacterial activity, pharmacological properties and therapeutic use.

Ceftriaxone is a new 'third generation' semisynthetic cephalosporin with a long half-life which has resulted in a recommended once daily administration schedule. It is administered intravenously or intramuscularly and has a broad spectrum of activity against Gram-positive and Gram-negative aerobic, and some anaerobic, bacteria. The activity of ceftriaxone is generally greater than that of the 'first' and 'second generation' cephalosporins against Gram-negative bacteria, but less than that of the earlier generations of cephalosporins against many Gram-positive bacteria. Although ceftriaxone has some activity against Pseudomonas aeruginosa, on the basis of present evidence it cannot be recommended as sole antibiotic therapy in pseudomonal infections. Ceftriaxone has been effective in treating infections due to other 'difficult' organisms such as multidrug-resistant Enterobacteriaceae. Ceftriaxone was effective in complicated and uncomplicated urinary tract infections, lower respiratory tract infections, skin, soft tissue, bone and joint infections, bacteraemia/septicaemia, and paediatric meningitis due to susceptible organisms. In most of these types of infections once-daily administration appears efficacious. Results were also encouraging in a few patients with ear, nose and throat, intra-abdominal, obstetric and gynaecological infections, and adult meningitis, but conclusions are not yet possible as to the efficacy of the drug in these indications due to limited experience. A single intramuscular dose of ceftriaxone has been compared with standard therapy for gonorrhoea due to non-penicillinase-producing and penicillinase-producing strains of Neisseria gonorrhoeae and shown to be highly effective. In a few small trials the comparative efficacy of ceftriaxone and other antibacterials has been assessed in other types of infections and in perioperative prophylaxis in patients undergoing surgery. Few significant differences in response rates were found between therapeutic groups in these comparative studies, but larger well-designed studies are needed to more clearly assess the comparative efficacy of ceftriaxone and other antimicrobials, especially the aminoglycosides and other 'third generation' cephalosporins, and to confirm the apparent lack of serious side effects with ceftriaxone. If more widespread use confirms the safety and efficacy of ceftriaxone, it will offer an important alternative, particularly for the treatment of serious infections due to multidrug-resistant Gram-negative bacteria and in situations where the long half-life of the drug could result in worthwhile convenience and cost benefits.

Aging↗

Isotretinoin. A review of its pharmacological properties and therapeutic efficacy in acne and other skin disorders.

Isotretinoin is a new orally active retinoic acid derivative for the treatment of severe refractory nodulocystic acne. The pharmacological profile of isotretinoin suggests that it acts primarily by reducing sebaceous gland size and sebum production, and as a result alters skin surface lipid composition. Bacterial skin microflora is reduced, probably as a result of altered sebaceous factors. Isotretinoin 1 to 2 mg/kg/day for 3 to 4 months produces 60 to 95% clearance of inflammatory lesions in patients with severe, recalcitrant nodulocystic acne, with evidence of continued healing and prolonged remissions in many patients after treatment withdrawal. Doses as low as 0.1 mg/kg/day have also proven successful in the clearance of lesions; however, with such low doses the duration of remission after discontinuation of therapy is usually shorter. Encouraging results have also been seen in small numbers of patients with rosacea, Gram-negative folliculitis, Darier's disease, ichthyosis and pityriasis rubra pilaris, the response in keratinising disorders resembling that with the related drug etretinate. While long term follow-up studies in these patients have not been reported, prolonged remission after withdrawal of isotretinoin in disorders of keratinisation is unlikely, as with other drugs used in these conditions. Isotretinoin is only partially effective in psoriasis, in contrast to etretinate which is very effective in psoriasis but ineffective in severe acne. Some encouraging results have also been reported with isotretinoin in patients with squamous and basal cell carcinomas, but isotretinoin has proven unsuccessful in non-squamous cell epithelial and non-epithelial cancer. Side effects affecting the mucocutaneous system occur in nearly all patients receiving isotretinoin, but rarely lead to drug withdrawal. Raised serum triglyceride levels are also commonly reported. The possibility of long term spinal or skeletal bone toxicity may restrict the use of isotretinoin in severe disorders of keratinisation requiring prolonged administration. Isotretinoin is strictly contraindicated in women of childbearing potential due to its severe teratogenic properties, unless an effective form of contraception is used. Thus, isotretinoin offers an effective advance on the treatment options available in a difficult therapeutic area - those patients with severe, nodulocystic acne not responding to 'traditional' therapy.

Acne Vulgaris↗