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Biomedical subjects

D H Peters

Publications and source records attributed to D H Peters.

26 records · Page 2Linked to original sources
PubMed1993

Tacrolimus. A review of its pharmacology, and therapeutic potential in hepatic and renal transplantation.

Tacrolimus (FK 506) is a macrolide immunosuppressant which possesses similar but more potent immunosuppressant properties compared with cyclosporin, inhibiting cell-mediated and humoral immune responses. Like cyclosporin, tacrolimus demonstrates considerable interindividual variation in its pharmacokinetic profile. This has caused difficulty in defining the optimum dosage regimen and has highlighted the usefulness of therapeutic drug monitoring. Most clinical studies with tacrolimus have neither been published in their entirety nor subjected to extensive peer review; there is also a paucity of published randomised investigations of tacrolimus versus cyclosporin, particularly in renal transplantation. Despite these drawbacks, tacrolimus has shown notable efficacy as a rescue or primary immunosuppressant therapy when combined with corticosteroids in adult and paediatric recipients following liver or kidney transplantation. Indeed, graft salvage rates in patients experiencing rejection or drug-related toxicity were > or = 50%, although data in renal transplantation are limited. Compared with cyclosporin as a primary immunosuppressant, tacrolimus showed comparable or greater patient/graft survival rates in liver allograft recipients (where cost savings associated with reduced hospitalisation costs were evident in one study), and comparable patient/graft survival in patients following kidney transplantation. Worthy of note was the efficacy of tacrolimus as a primary immunosuppressant in patients who received en bloc kidney allografts. The incidence of rejection was largely reduced following rescue therapy with tacrolimus and was generally lower (notably for refractory rejection) than that observed for cyclosporin, at least in liver allograft recipients. This was reflected in less need for adjunct immunotherapy including antilymphocyte preparations for the treatment of rejection episodes. The potential for reduction or withdrawal of corticosteroid therapy with tacrolimus appears to be a distinct advantage compared with cyclosporin, and this may be enhanced by the reduced incidence of infectious complications and of hypertension and hypercholesterolaemia reported by some investigators. In other respects, however, the tolerability profile of tacrolimus appears to be broadly similar to that of cyclosporin. Against this background, preliminary data indicate that tacrolimus provides a valuable therapeutic alternative to retransplantation in patients experiencing liver or kidney graft rejection or drug-related toxicity. Pending confirmation of initial randomised studies and preliminary results from large randomised investigations, tacrolimus may well be considered as an alternative primary immunosuppressant to cyclosporin in hepatic (particularly) and renal transplantation. Furthermore, the steroid-sparing effects of tacrolimus, although of benefit to all patient groups, may prove to be of particular worth in children and in en bloc kidney recipients. In these patients tacrolimus may well emerge as the drug of choice.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

Cetirizine. A reappraisal of its pharmacological properties and therapeutic use in selected allergic disorders.

Cetirizine, the carboxylated metabolite of hydroxyzine, is a specific and long-acting histamine H1-receptor antagonist. It has marked antiallergic properties and inhibits eosinophil chemotaxis during the allergic response. Clinical trial results indicate that cetirizine is an effective and well tolerated treatment for seasonal/perennial allergic rhinitis and chronic idiopathic urticaria in adults, and for seasonal/perennial allergic rhinitis in children. Cetirizine 10 mg/day appears to be as effective as conventional dosages of other established antihistamines such as astemizole, hydroxyzine, ketotifen, loratadine or terfenadine in relieving symptoms of these disorders, and is associated with a significantly lower incidence of sedation than hydroxyzine. However, when sedation was subjectively assessed, cetirizine appeared to be more sedating than placebo, loratadine or terfenadine in some clinical trials. This difference was not observed in several other double-blind studies. In contrast, when assessed objectively in pharmacodynamic comparisons, cetirizine was rarely more sedating than placebo or other second generation histamine H1-receptor antagonists. Cetirizine may also have a role in the treatment of certain forms of physical urticaria, atopic dermatitis and reactions to mosquito bites. In addition, it is being studied for the treatment of allergic asthma in adults and children. The pharmacokinetic profile and predominantly renal excretion of cetirizine suggest that this agent may have a reduced potential for adverse drug interactions involving hepatic enzyme systems compared with other histamine H1-receptor antagonists which are extensively metabolised. Thus, cetirizine, with its rapid onset and long duration of action, appears to provide a useful alternative to the antihistamine agents in clinical use.

Administration, Oral↗
PubMed1993

The determinants of use of maternal and child health services in Metro Cebu, the Philippines.

The determinants of the use of family planning, prenatal care, childhood immunizations and oral rehydration salts (ORS) were studied with survey data of 8000 women in Metro Cebu, the Philippines. Polytomous logistic regression methods were used. The level of maternal education was the most consistent and important determinant of use of these four health services in both urban and rural areas. For example, the estimated odds of using modern contraception increased by six and eleven per cent for each additional year of schooling in urban and rural strata respectively. Economic status and access to service variables had less consistent patterns: women's work status, for example, was associated only with contraceptive use.

Adolescent↗
PubMed1992

Clarithromycin. A review of its antimicrobial activity, pharmacokinetic properties and therapeutic potential.

Clarithromycin is an acid-stable orally administered macrolide antimicrobial drug, structurally related to erythromycin. It has a broad spectrum of antimicrobial activity, similar to that of erythromycin and inhibits a range of Gram-positive and Gram-negative organisms, atypical pathogens and some anaerobes. Significantly, clarithromycin demonstrates greater in vitro activity than erythromycin against certain pathogens including Bacteroides melaninogenicus, Chlamydia pneumoniae, Chlamydia trachomatis, Mycobacterium chelonae subspecies--chelonae and--abscessus, Mycobacterium leprae, Mycobacterium marinum, Mycobacterium avium complex, Legionella spp. and, when combined with its 14-hydroxy metabolite, against Haemophilus influenzae. However, bacterial strains resistant to erythromycin are also generally resistant to clarithromycin. The antimicrobial activity of clarithromycin appears to be enhanced by the formation in vivo of the microbiologically active 14-hydroxy metabolite. In combination, additive or synergistic activity against a variety of pathogens including Haemophilus influenzae, Moraxella catarrhalis, Legionella species (principally Legionella pneumophila) and various staphylococci and streptococci has been demonstrated. Clarithromycin has a superior pharmacokinetic profile to that of erythromycin, allowing the benefits of twice daily administration with the potential for increased compliance among outpatients where a more frequent regimen for erythromycin might otherwise be indicated. The clinical efficacy of clarithromycin has been confirmed in the treatment of infections of the lower and upper respiratory tracts (including those associated with atypical pathogens), skin/soft tissues, and in paediatrics. Clarithromycin was as effective as erythromycin and other appropriate drugs including beta-lactams (penicillins and cephalosporins) in some of the above infections. A most promising indication for clarithromycin appears to be in the treatment of immunocompromised patients infected with M. avium complex, M. chelonae sp. and Toxoplasma sp. Small initial trials in this setting reveal clarithromycin alone or in combination with other antimicrobials to be effective in the eradication or amelioration of these infections. Noncomparative studies have provided preliminary evidence for the effectiveness of clarithromycin in the treatment of infections of the urogenital tract, oromaxillofacial and ophthalmic areas. However, the promising in vitro and preliminary in vivo activity of clarithromycin against Mycobacterium leprae and Helicobacter pylori warrant further clinical trials to assess its efficacy in patients with these infections. Despite the improved pharmacokinetic profile and in vitro antimicrobial activity of clarithromycin over erythromycin, comparative studies of patients with community-acquired infections reveal the 2 drugs to be of equivalent efficacy. However, clarithromycin demonstrates greater tolerability, principally by inducing fewer gastrointestinal disturbances.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1992

Azithromycin. A review of its antimicrobial activity, pharmacokinetic properties and clinical efficacy.

Azithromycin is an acid stable orally administered macrolide antimicrobial drug, structurally related to erythromycin, with a similar spectrum of antimicrobial activity. Azithromycin is marginally less active than erythromycin in vitro against Gram-positive organisms, although this is of doubtful clinical significance as susceptibility concentrations fall within the range of achievable tissue azithromycin concentrations. In contrast, azithromycin appears to be more active than erythromycin against many Gram-negative pathogens and several other pathogens, notably Haemophilus influenzae, H. parainfluenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, Urea-plasma urealyticum and Borrelia burgdorferi. Like erythromycin and other macrolides, the activity of azithromycin is unaffected by the production of beta-lactamase. However, erythromycin-resistant organisms are also resistant to azithromycin. Following oral administration, serum concentrations of azithromycin are lower than those of erythromycin, but this reflects the rapid and extensive movement of the drug from the circulation into intracellular compartments resulting in tissue concentrations exceeding those commonly seen with erythromycin. Azithromycin is subsequently slowly released, reflecting its long terminal phase elimination half-life relative to that of erythromycin. These factors allow for a single dose or single daily dose regimen in most infections, with the potential for increased compliance among outpatients where a more frequent antimicrobial regimen might traditionally be indicated. The potential disadvantage of low azithromycin serum concentrations, however, is that breakthrough bacteraemia may occur in patients who are severely ill; nevertheless, animal studies suggest that tissue concentrations of azithromycin are more important than those in serum when treating respiratory and other infections. The clinical efficacy of azithromycin has been confirmed in the treatment of infections of the lower and upper respiratory tracts (the latter including paediatric patients), skin and soft tissues (again including paediatric patients), in uncomplicated urethritis/cervicitis associated with N. gonorrhoeae, Chlamydia trachomatis or U. urealyticum and in the treatment of early Lyme disease. Azithromycin was as effective as erythromycin and other commonly used drugs including clarithromycin, beta-lactams (penicillins and cephalosporins), and quinolone and tetracycline antibiotics in some of the above infections. Some patients with acute exacerbations of chronic bronchitis due to H. influenzae may be refractory to therapy with azithromycin (as is the case with erythromycin) indicating the need for physician vigilance, although it should be noted that azithromycin is of equivalent efficacy to amoxicillin in the treatment of such patients. In the therapy of urethritis/cervicitis associated with C. trachomatis, N. gonorrhoea or U. urealyticum, a single dose azithromycin regimen offers a distinct advantage over currently available pharmacological options, while providing effective therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1976

Cyst of seminal vesicle with ipsilateral renal agenesis and ectopic ureter: case report.

A 24-year-old man had a cyst of the seminal vesicle and ipsilateral renal agenesis with an ectopic ureter. Nineteen other patients with similar anomalies are reviewed. The usual age at the onset of symptoms is between 20 and 28 years, during the time of maximal reproductive activity. Usually, diagnosis is established by history, the finding of a mass in the area of the seminal vesicle and an excretory urogram. Treatment consists of excision, aspiration or transurethral unroofing of the cyst.

Adult↗