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Biomedical subjects

M C Nahata

Publications and source records attributed to M C Nahata.

At least 37 records · Page 2Linked to original sources
PubMed2000

Treatment of pediatric hypertension.

We conducted a MEDLINE search from January 1966-March 1999 to obtain information on clinical trials of treatment of pediatric hypertension. An article was selected for review if it described a randomized or nonrandomized study; randomized studies were given priority. Case reports were considered when studies were unavailable. Review articles were useful in identifying references. According to data we collected, hypertension is present in 1-3% of the pediatric population. Nonpharmacologic treatment may be effective initially in those with mild to moderate disease or as an adjunct to drug therapy. Drugs for treatment of chronic hypertension include calcium channel blockers, angiotensin-converting enzyme inhibitors, diuretics, and beta-blockers. Patient and drug characteristics determine therapy. Intravenous labetalol, nicardipine, and nitroprusside are effective for treating hypertensive emergencies.

Antihypertensive Agents↗
PubMed2000

Cardiotoxicity of chemotherapeutic agents: incidence, treatment and prevention.

Cytostatic antibiotics of the anthracycline class are the best known of the chemotherapeutic agents that cause cardiotoxicity. Alkylating agents such as cyclophosphamide, ifosfamide, cisplatin, carmustine, busulfan, chlormethine and mitomycin have also been associated with cardiotoxicity. Other agents that may induce a cardiac event include paclitaxel, etoposide, teniposide, the vinca alkaloids, fluorouracil, cytarabine, amsacrine, cladribine, asparaginase, tretinoin and pentostatin. Cardiotoxicity is rare with some agents, but may occur in >20% of patients treated with doxorubicin, daunorubicin or fluorouracil. Cardiac events may include mild blood pressure changes, thrombosis, electrocardiographic changes, arrhythmias, myocarditis, pericarditis, myocardial infarction, cardiomyopathy, cardiac failure (left ventricular failure) and congestive heart failure. These may occur during or shortly after treatment, within days or weeks after treatment, or may not be apparent until months, and sometimes years, after completion of chemotherapy. A number of risk factors may predispose a patient to cardiotoxicity. These are: cumulative dose (anthracyclines, mitomycin); total dose administered during a day or a course (cyclophosphamide, ifosfamide, carmustine, fluorouracil, cytarabine); rate of administration (anthracyclines, fluorouracil); schedule of administration (anthracyclines); mediastinal radiation; age; female gender; concurrent administration of cardiotoxic agents; prior anthracycline chemotherapy; history of or pre-existing cardiovascular disorders; and electrolyte imbalances such as hypokalaemia and hypomagnesaemia. The potential for cardiotoxicity should be recognised before therapy is initiated. Patients should be screened for risk factors, and an attempt to modify them should be made. Monitoring for cardiac events and their treatment will usually depend on the signs and symptoms anticipated and exhibited. Patients may be asymptomatic, with the only manifestation being electrocardiographic changes. Continuous cardiac monitoring, baseline and regular electrocardiographic and echocardiographic studies, radionuclide angiography and measurement of serum electrolytes and cardiac enzymes may be considered in patients with risk factors or those with a history of cardiotoxicity. Treatment of most cardiac events induced by chemotherapy is symptomatic. Agents that can be used prophylactically are few, although dexrazoxane, a cardioprotective agent specific for anthracycline chemotherapy, has been approved by the US Food and Drug Administration. Cardiotoxicity can be prevented by screening and modifying risk factors, aggressively monitoring for signs and symptoms as chemotherapy is administered, and continuing follow-up after completion of a course or the entire treatment. Prompt measures such as discontinuation or modification of chemotherapy or use of appropriate drug therapy should be initiated on the basis of changes in monitoring parameters before the patient exhibits signs and symptoms of cardiotoxicity.

Angiogenesis Inhibitors↗
PubMed1999

Stability of fumagillin in an extemporaneously prepared ophthalmic solution.

The stability of fumagillin 70 microg/mL (as the bicyclohexylammonium crystal) in an extemporaneously prepared ophthalmic solution was studied. An ophthalmic solution of fumagillin 70 microg/mL was prepared by combining 120 mg of fumagillin bicyclohexylammonium crystals with 20 mL of 0.9% Sodium Chloride Injection, USP, and 20 mL of an ophthalmic irrigating solution. The solution was stored in 12 sterile semi-opaque dropper bottles; 4 bottles were stored at 25 degrees C exposed to light, 4 were stored at 25 degrees C in the dark, and 4 were stored at 4 degrees C in the dark. Samples were taken on days 0, 7, 14, 21, and 28 and analyzed by high-performance liquid chromatography. Sterility was tested as well. In the solutions stored at 25 degrees C, 17-30% of the initial drug concentration was lost during the first week. The solution protected from light and stored at 4 degrees C lost about 12% of active drug by week 4. There was no change in color or odor in any of the solutions and only a minor change in pH over the study period. There was no evidence of microbial growth in any of the solutions tested. Fumagillin 70 microg/mL (as the bicyclohexylammonium crystal) in 0.9% sodium chloride injection and an ophthalmic irrigating solution containing benzalkonium chloride was stable in the dark for 14 days at 4 degrees C.

Antiprotozoal Agents↗
PubMed1999

Stability of lamotrigine in two extemporaneously prepared oral suspensions at 4 and 25 degrees C.

The stability of lamotrigine 1 mg/mL in two extemporaneously prepared oral suspensions at 4 and 25 degrees C was studied. Lamotrigine tablets were ground to powder, and the powder was combined with a 1:1 mixture of Ora-Sweet and Ora-Plus or a 1:1 mixture of Ora-Sweet SF and Ora-Plus (Paddock Laboratories) to produce two 1-mg/mL suspensions. One 100-mg lamotrigine tablet was used to prepare one 100-mL batch of each suspension. The suspensions were stored in amber polyethylene terephthalate prescription bottles at 4 or 25 degrees C. Samples were collected on days 0, 7, 14, 28, 42, 56, 70, and 91 for analysis of lamotrigine content by high-performance liquid chromatography; pH was measured, and the samples were visually observed against a black and white background. The mean concentration of lamotrigine was >99% of the initial concentration in all samples throughout the 91-day study period; there was no change in apparent pH, odor, or physical appearance. Lamotrigine 1 mg/mL in two extemporaneously compounded oral suspensions was stable for 91 days in polyethylene terephthalate prescription bottles at 4 and 25 degrees C.

Administration, Oral↗
PubMed1999

Stability of terbinafine hydrochloride in an extemporaneously prepared oral suspension at 25 and 4 degrees C.

The stability of terbinafine 25 mg/mL (as the hydrochloride salt) in an extemporaneously prepared oral suspension at 25 and 4 degrees C was studied. Twenty 250-mg terbinafine tablets were crushed to a fine powder and diluted to a concentration of 25 mg/mL with sweetened vehicle. The suspension was stored in amber polyethylene prescription bottles at 25 or 4 degrees C. Samples were taken on days 0, 7, 14, 28, 42, 56, 70, and 91 for duplicate analysis of terbinafine content by high-performance liquid chromatography and to observe any changes in color and odor; pH was measured as well. Through the initial 42 days, the mean concentration of terbinafine in the samples stored at both temperatures was >93% of the initial concentration; by day 56, the mean concentration was <88%. No appreciable changes in color or odor were observed during the study period. The apparent pH of the suspension decreased slightly over the 91 days, from an initial 5.6 to 5.5. Terbinafine 25 mg/mL (as the hydrochloride salt) in an extemporaneously prepared oral suspension was stable for up to 42 days in polyethylene prescription bottles at 25 and 4 degrees C.

Administration, Oral↗
PubMed1999

Efficacy of amlodipine in pediatric patients with hypertension.

We designed a study to determine the efficacy and safety of amlodipine given once daily in the pediatric population. Twenty-one patients (mean age 13.1 years) with either essential (n=160) or renal (n=5) hypertension, and newly diagnosed (n=15) or poorly controlled or intolerant on existing antihypertensive therapy (n=6), were included. Patients received amlodipine once daily at a starting mean dose of 0.07+/-0.04 mg/kg per day. The total daily dose of amlodipine was increased 25%-50% every 5-7 days if the mean home blood pressure measurements (HBPM) were above the 95th percentile for age and gender. A baseline followed by a repeat 24-h ambulatory blood pressure monitor study (ABPM) was performed in 20 patients when the mean HBPM was below the 95th percentile goal. The mean titrated dose required to control BP was 0.29+/-0.11 mg/kg per day for those < 13 years, 0.16+/-0.11 mg/kg per day for those > or = 13 years, 0.23+/-0.14 mg/kg per day for essential, hypertension and 0.24+/-0.13 mg/kg per day for renal hypertension. The ABPM demonstrated that amlodipine provided effective BP control as primary therapy in 14 essential patients. Adverse effects included fatigue (n=6), headache (n=5), facial flushing (n=4), dizziness (n=3), edema (n=3), abdominal pain (n=3), chest pain (n=2), nausea (n=1), and vomiting (n=1). Quality of life appeared to improve during therapy. Amlodipine was an effective once daily antihypertensive agent with an acceptable safety profile. Higher doses of amlodipine were required for younger patients, and monotherapy was effective in patients with essential hypertension.

Administration, Oral↗
PubMed1999

Development of two stable oral suspensions for gabapentin.

Gabapentin is not available in a liquid dosage form for clinical use. This study was designed to develop two oral gabapentin suspensions and determine their stability under refrigeration or at room temperature. Commercially available gabapentin capsules were used to prepare two suspensions: one in extemporaneously prepared 1% methylcellulose in syrup (1:1) and another in equal volumes of commercially available suspending agents/syrup (Ora Plus/Ora Sweet). Each suspension containing gabapentin (100 mg/mL) was stored in 10 plastic prescription bottles; five were stored at 4 degrees C and five at 25 degrees C. Three 500-microL samples were collected immediately after preparation (day 0) and on days 7, 14, 28, 42, 56, 70, and 91. Gabapentin was measured by accurate, reproducible, specific, and stability-indicating high-performance liquid chromatography (n = 15). The observed mean concentrations exceeded 90% of the initial concentrations in both suspensions for 91 days at 4 degrees C and 56 days at 25 degrees C. No change in pH, odor, or physical appearance was observed. On the basis of these results, stable oral suspensions of gabapentin can be prepared and stored in plastic prescription bottles for 91 days at 4 degrees C or 56 days at 25 degrees C.

Acetates↗
PubMed1999

A comparative review of conventional and lipid formulations of amphotericin B.

Over the past 15 years, factors suh as corticosteroid treatment, cytotoxic chemotherapy, excessive use of broad spectrum antibiotics and HIV have led to an increased risk of serious fungal infections in both adults and pediatric patients. This increase in invasive fungal infections poses increasing difficulty in their treatment. Three new lipid formulations of amphotericin B are now available in the U.S.: amphotericin B lipid complex (Abelcet), amphotericin B colloidal dispersion (Amphotec), and liposomal amphotericin B (AmBisome). These newer formulations are substantially more expensive, but allow patients to receive higher doses for longer periods of time with decreased renal toxicity than conventional amphotericin B. The properties of these new agents are summarized in this review. Discussion of current national guidelines as well as those used at our institution are presented to provide guidance for the development of institution specific guidelines for the most cost-effective drug for most patients, some may benefit more from one of the newer lipid formulations.

Amphotericin B↗
PubMed1999

Pharmacokinetics of ampicillin and sulbactam in pediatric patients.

Intravenous ampicillin-sulbactam is effective in the treatment of various infections in adults, but little is known about the pharmacokinetics (PK) of ampicillin-sulbactam in children. The objective of this study was to determine the PK of ampicillin and sulbactam in pediatric patients with intra-abdominal infection, skin and/or skin structure infection, or periorbital-preseptal and facial cellulitis. Intravenous ampicillin and sulbactam (2:1), 40 to 80 mg/kg of body weight, were given every 6 h for 2 to 6 days to 28 pediatric patients. The ages ranged from 1 to 6 years for 10 patients, 6.1 to 10 years for 9 patients, and 10.1 to 12 years for 9 patients. Multiple blood samples were obtained and analyzed for ampicillin and sulbactam in plasma and serum by high-performance liquid chromatography. The mean maximum concentration of drug in serum ranged from 177 to 200 micrograms/ml for ampicillin and 82 to 102 micrograms/ml for sulbactam in the three age groups. The mean total clearance, steady-state distribution volume, and half-life were 4.76 ml/min/kg, 0.32 liter/kg, and 0.77 h, respectively, for ampicillin and 4.95 ml/min/kg, 0.34 liter/kg, and 0.81 h, respectively, for sulbactam. Dose or gender did not affect the PK of ampicillin or sulbactam. The PK of ampicillin and sulbactam in these patients were comparable to those reported in adults. The combination was well tolerated in pediatric patients.

Adult↗
PubMed1999

Trovafloxacin: a new fluoroquinolone.

OBJECTIVE: To review the pharmacology, antimicrobial activity, pharmacokinetics, clinical efficacy, and safety of trovafloxacin. DATA SOURCES: A MEDLINE search (January 1966-April 1998) was conducted for relevant literature using the terms CP-99,219, CP-116,519, trovafloxacin, and alatrofloxacin. Abstracts published by the American Society of Microbiology during 1995-1997 meetings were also reviewed. STUDY SELECTION AND DATA EXTRACTION: All in vitro, animal, and human studies were reviewed for the antimicrobial activity, pharmacokinetics, efficacy, and safety of trovafloxacin. DATA SYNTHESIS: Trovafloxacin is a new fluoroquinolone with enhanced activity against gram-positive and anaerobic microorganisms. The oral bioavailability under fasting conditions is approximately 88%. The elimination half-life of trovafloxacin is approximately 10 hours. Less than 10% of trovafloxacin is eliminated unchanged in the urine. Trovafloxacin is effective in the treatment of community-acquired pneumonia and nosocomial pneumonia with cure rates of > 90% and 77%, respectively. Trovafloxacin is comparable with ceftriaxone in the treatment of meningococcal meningitis in children; each produces a cure rate of approximately 90%. In treatment of uncomplicated urinary tract infection, both ciprofloxacin and trovafloxacin achieve an eradication rate of > or = 93%. Trovafloxacin is similar to ofloxacin in the treatment of urogenital Chlamydia trachomatis and acute exacerbations of chronic bronchitis, with clinical success in 97% of patients with each drug. The common adverse effects of trovafloxacin include dizziness, headache, and gastrointestinal intolerance. CONCLUSIONS: The advantages of once-daily dosing and enhanced activity of trovafloxacin against gram-positive and anaerobic organisms may expand its use over available fluoroquinolones. Further studies are needed to define its role in the treatment of various infectious diseases.

Animals↗
PubMed1999

Nelfinavir mesylate: a protease inhibitor.

OBJECTIVE: To review the clinical pharmacology, pharmacokinetics, efficacy, adverse effects, drug interactions, and dosage guidelines of nelfinavir mesylate. DATA SOURCE: A MEDLINE search restricted to English-language literature from January 1966 to February 1998 and an extensive review of journals was conducted to prepare this article. MeSH headings included protease inhibitors, nelfinavir mesylate, and AG1343. Abstracts presented at meetings and data submitted to the Food and Drug Administration (FDA) were also reviewed. DATA EXTRACTION: The data on efficacy, pharmacokinetics, adverse effects, and drug interactions were obtained from in vitro studies, as well as open-label and controlled trials. DATA SYNTHESIS: Nelfinavir inhibits HIV protease enzyme resulting in formation of immature and noninfectious virions. In combination with nucleoside reverse transcriptase inhibitors, nelfinavir is effective in reducing the viral load below the quantifiable limit (< 500 copies/mL) and increasing the mean CD4+ cell count. This antiviral effect is sustained at least over 21 months. The bioavailability of nelfinavir ranges from 20% to 80%, and it increases when nelfinavir is administered with food. Following multiple dosing of nelfinavir 750 mg three times daily, maximum concentration at steady-state was 3-4 micrograms/mL and minimum concentration was 1-3 micrograms/mL. The elimination half-life for nelfinavir ranges from three to five hours. Nelfinavir is primarily metabolized in the liver by the cytochrome P450 isoenzymes and excreted in the feces. Current dosing recommendations are 750 mg three times daily for adults and adolescents and 20-30 mg/kg/dose three times daily for children aged 2-13 years. Studies of twice-daily regimens in adults are being conducted and are promising. Use of nelfinavir as salvage therapy is also being studied. Some of the commonly reported adverse events of nelfinavir are diarrhea, nausea, vomiting, and abdominal pain. CONCLUSIONS: Despite the limited published data, the FDA has approved nelfinavir in combination therapy for the treatment of HIV infection. The choice of antiretroviral (ARV) regimens should be made based on the risk of disease progression as indicated by HIV RNA concentrations and CD4+ cell counts, patients' previous ARV experiences and responses, concomitant drug therapy, compliance history, underlying disease states, and adverse reaction history.

Adolescent↗
PubMed1999

Pediatric drug formulations: challenges and potential solutions.

Lack of pediatric drug formulations for both currently marketed and new drugs continues to be a challenge. Marketing of commercial products, along with pediatric indications, would be the ultimate solution to the lack of pediatric drug formulations. However, until that occurs, funding of research on extemporaneous formulations proposed by scientists should be a high priority. Government, academia, industry, the USPC, and professional associations should collaborate in developing the best policies and an action plan. Infants and children should not be expected to wait for stable extemporaneous formulations of important drugs until an unrealistic goal of having all generic and new drugs available commercially in suitable formulations has been realized.

Chemistry, Pharmaceutical↗
PubMed1999

Chlamydia pneumoniae and coronary heart disease.

OBJECTIVE: To review the potential association between Chlamydia pneumoniae (CP) infection and coronary artery disease (CAD), and to describe possible therapeutic interventions. DATA SOURCES: A MEDLINE search of literature (January 1966-January 1998) pertaining to CP infection associated with heart disease was performed. Additional literature was obtained from review of journals and reference lists of pertinent articles identified through the search. STUDY SELECTION AND DATA EXTRACTION: All articles involving CP and CAD were considered for possible inclusion in this review. Other selected articles involved possible links between infection and the atherosclerotic process, inflammation and inflammatory mediators in the atherosclerotic process, and isolation of CP from human tissue. DATA SYNTHESIS: Numerous reports have suggested an association between chronic CP and CAD. CP has been seroepidemiologically linked to CAD. The organism has also been isolated from atherosclerotic lesions. Two reports in humans and one report in animals have shown that macrolide therapy (azithromycin or roxithromycin) may decrease the risk of adverse cardiovascular events. CONCLUSIONS: Evidence seems to support an association between CP infection and an increased incidence of CAD. Additional and larger seroepidemiologic studies of this association need to be performed to establish a causal relationship between infection and CAD. Determination of the actual role of CP in CAD may decide the role of specific antichlamydial therapy in the management of this condition.

Animals↗
PubMed1999

Rifapentine: its role in the treatment of tuberculosis.

OBJECTIVE: To review the pharmacokinetics, efficacy, adverse effects, and cost of the newest antitubercular drug, rifapentine. DATA SOURCES: A MEDLINE search using key terms such as rifapentine, rifampin, isoniazid, Mycobacterium tuberculosis, and pyrazinamide was conducted for the time period 1966-November 1998. STUDY SELECTION: Animal data were used for basic information and human studies were selected for inclusion if they were randomized, controlled studies assessing efficacy, or if they were single- or multiple-dose studies assessing the pharmacokinetics of rifapentine. Background articles on the pathophysiology of tuberculosis and cost of care and noncontrolled studies assessing drug interactions were also included. DATA SYNTHESIS: Compared with an oral solution, the relative bioavailability of rifapentine is 70% following oral admninistration of tablets. Food increased bioavailability by 55%. Rifapentine accumulated significantly in human macrophages and its elimination half-life was longer than that of rifampin. Comparative studies of rifapentine and rifampin in humans during intensive- and continuation-phase treatment of tuberculosis suggest that at currently accepted doses, rifapentine was slightly less effective than rifampin. The most significant drug interaction with rifapentine involves indinavir: the maximum concentration and AUC of indinavir are reduced by 55% and 70%, respectively, when rifapentine is coadministered with indinavir. Adverse events of rifapentine may occur less frequently at the currently recommended 600-mg dose as compared with rifampin; however, the difference was not statistically significant. If only drug costs were evaluated during the six-month treatment of tuberculosis, rifapentine is more expensive than rifampin. CONCLUSIONS: Rifapentine can be administered twice weekly during the intensive phase of tuberculosis treatment and then once weekly during the continuation phase of treatment. This may improve patient adherence over some other treatments and possibly reduce costs of treatment by preventing development of resistant tubercular strains due to nonadherence. Rifapentine is well tolerated, with most patients experiencing adverse effects at a similar rate as rifampin. Rifapentine induces cytochrome P450 somewhat less than rifampin, although few drug interaction studies have been done with rifapentine. Its efficacy at the currently approved dosage of 600 mg may be slightly lower than that of rifampin. Studies are needed to determine if equal or greater efficacy can be achieved with higher doses of rifapentine. Rifampin is less expensive than rifapentine. Further pharmacoeconomic studies are needed to evaluate costs of relapse and failure in patients receiving these agents.

Abnormalities, Drug-Induced↗
PubMed1999

Lack of pediatric drug formulations.

Many drugs frequently used in infants and young children are not available in suitable dosage forms. Liquid dosage forms must be prepared extemporaneously, while using appropriate excipients. However, it is critical to determine the stability of various drugs at clinically important concentrations and practical storage conditions. It is of concern that few funding agencies are willing to support research on the development of stable liquid dosage forms for pediatric patients. The need for such data will continue, because it is unlikely that all drugs approved for adults will also be labeled simultaneously for potential use in infants and children. Presentations and publications on stable drug formulations will offer the opportunities for pediatric patients to receive the desired drugs and doses most effectively and safely.

Adult↗
PubMed1998

Stability of enalapril maleate in three extemporaneously prepared oral liquids.

The stability of enalapril 1 mg/mL (as the maleate) in deionized water, citrate buffer solution, and a sweetened suspending agent at two temperatures was studied. Twenty enalapril 10-mg tablets were crushed to a powder. Deionized water, citrate buffer solution, or sweetened vehicle was added to produce three 200-mL batches of each liquid; the expected final concentration of enalapril in each was 1 mg/mL. Each formulation was stored in 10 60-mL bottles, 5 of which were stored at 4 degrees C and 5 at 25 degrees C. Samples were collected on days 0, 7, 14, 28, 42, 56, 70, and 91 for visual inspection and analysis by high-performance liquid chromatography; pH was measured at each sampling time as well. The mean concentration of enalapril in the three liquids at 4 degrees C was > 94% of the initial concentration throughout the 91-day study period. At 25 degrees C, the mean concentration of enalapril was > 90% for 56 days and > 92% for 91 days in both citrate buffer solution and sweetened vehicle. The pH of the liquid prepared with deionized water and stored at 25 degrees C decreased by 2.0 pH units. Enalapril 1 mg/mL (as the maleate) in three extemporaneously compounded oral liquids was stable for 91 days at 4 and 25 degrees C with the exception of enalapril in deionized water, which was stable for only 56 days at 25 degrees C.

Angiotensin-Converting Enzyme Inhibitors↗