Comment on the potential utility of the new atypical antipsychotic lurasidone in the geriatric population

Lurasidone is the tenth atypical antipsychotic to be marketed in the United States. Like other atypical agents, lurasidone binds to a variety of central nervous system receptors, including dopamine (D2), norepinephrine (alpha 2A and 2C), and serotonin (1A, 2A, and 7) receptors. At these receptors, the drug acts as an antagonist except at serotonin 1A receptors, where it is a partial agonist. It behaves like an antipsychotic agent in animal models predictive of such activity. In addition, it behaves as a cognition enhancer in animal models of learning and memory impairment. In vivo in humans, lurasidone has been effective in significantly improving the positive and negative symptoms of schizophrenia in young adults as well as demonstrating preliminary positive effects on cognition in this population. The bioavailability of lurasidone is enhanced three-fold by administration with food. It is virtually completely metabolized, the major exo-hydroxy metabolite exhibiting the same pharmacology as the parent compound. Despite this, renal and hepatic impairment substantially affect the drug's pharmacokinetics, necessitating dose reduction or limitation. Several metabolic drug-drug interactions are clinically important (CYP450 isozyme 3A4-based). Lurasidone will be a difficult drug to use in the elder patient population because of the virtual absence of elder-specific information, limitations of existing formulations (40 and 80 mg nonscored tablets) in enabling precise dosage adjustment, and the substantial difference in bioavailability with food versus fasting, with attendant risks for over- and underdosing depending on when the drug is ingested. It would be prudent to avoid using this agent until relevant geriatric-specific data are published.

Dalbavancin: an investigational glycopeptide

Glycopeptide antimicrobials have been a component of our therapeutic armamentarium for nearly 50 years. Although vancomycin, and more recently teicoplanin, have performed yeoman service over the years, the specter of bacterial resistance among Gram-positive aerobes has created doubts concerning how long they will continue to be useful antimicrobial agents. In an attempt to prolong the utility of the glycopeptides, efforts are underway to create new derivatives with improved pharmacologic and pharmacokinetic properties. One example of an improved glycopeptide from the pharmacokinetic perspective is dalbavancin (BI397)--a teicoplanin analog currently undergoing human testing. Elimination of this compound from the body occurs extremely slowly, with terminal disposition half-lifes of up to 200 h in healthy volunteers, thus allowing once-weekly dosing. Although not generally considered to be a potential alternative for the treatment of infections due to glycopeptide-resistant Gram-positive pathogens, dalbavancin may still be considered an advance on existing agents based on its patient-convenient once-weekly dosing regimen.

Dabigatran etexilate: a possible replacement for heparinoids and vitamin K antagonists?

Dabigatran etexilate is the first oral anticoagulant to be approved in the United States in decades. It works directly by inhibiting clot-bound and free factor IIa (ie, thrombin) and indirectly by inhibiting platelet aggregation induced by thrombin. It is approved in the United States for stroke prophylaxis in nonvalvular atrial fibrillation. There is evidence to suggest that it is also effective for the treatment of acute venous thromboembolism and venous thromboembolism prophylaxis after knee and hip replacement surgery. Dabigatran etexilate therapy does not require laboratory monitoring, an advantage over warfarin. Unlike the earlier direct thrombin inhibitor, ximelagatran, it has demonstrated no potential for serious hepatotoxicity. It is also subject to a much lower degree of interpatient variability in dose response, has no diet-drug interactions, and has fewer clinically significant drug-drug interactions compared with warfarin. Dabigatran etexilate appears to be a valuable addition to our anticoagulant armamentarium.

Cranberry and urinary tract infections

Urinary tract infection (UTI) refers to the presence of clinical signs and symptoms arising from the genitourinary tract plus the presence of one or more micro-organisms in the urine exceeding a threshold value for significance (ranges from 102 to 103 colony-forming units/mL). Infections are localized to the bladder (cystitis), renal parenchyma (pyelonephritis) or prostate (acute or chronic bacterial prostatitis). Single UTI episodes are very common, especially in adult women where there is a 50-fold predominance compared with adult men. In addition, recurrent UTIs are also common, occurring in up to one-third of women after first-episode UTIs. Recurrences requiring intervention are usually defined as two or more episodes over 6 months or three or more episodes over 1 year (this definition applies only to young women with acute uncomplicated UTIs). A cornerstone of prevention of UTI recurrence has been the use of low-dose once-daily or post-coital antimicrobials; however, much interest has surrounded non-antimicrobial-based approaches undergoing investigation such as use of probiotics, vaccines, oligosaccharide inhibitors of bacterial adherence and colonization, and bacterial interference with immunoreactive extracts of Escherichia coli. Local (intravaginal) estrogen therapy has had mixed results to date. Cranberry products in a variety of formulations have also undergone extensive evaluation over several decades in the management of UTIs. At present, there is no evidence that cranberry can be used to treat UTIs. Hence, the focus has been on its use as a preventative strategy. Cranberry has been effective in vitro and in vivo in animals for the prevention of UTI. Cranberry appears to work by inhibiting the adhesion of type I and P-fimbriated uropathogens (e.g. uropathogenic E. coli) to the uroepithelium, thus impairing colonization and subsequent infection. The isolation of the component(s) of cranberry with this activity has been a daunting task, considering the hundreds of compounds found in the fruit and its juice derivatives. Reasonable evidence suggests that the anthocyanidin/proanthocyanidin moieties are potent antiadhesion compounds. However, problems still exist with standardization of cranberry products, which makes it extremely difficult to compare products or extrapolate results. Unfortunately, most clinical trials have had design deficiencies and none have evaluated specific key cranberry-derived compounds considered likely to be active moieties (e.g. proanthocyanidins). In general, the preventive efficacy of cranberry has been variable and modest at best. Meta-analyses have established that recurrence rates over 1 year are reduced approximately 35% in young to middle-aged women. The efficacy of cranberry in other groups (i.e. elderly, paediatric patients, those with neurogenic bladder, those with chronic indwelling urinary catheters) is questionable. Withdrawal rates have been quite high (up to 55%), suggesting that these products may not be acceptable over long periods. Adverse events include gastrointestinal intolerance, weight gain (due to the excessive calorie load) and drug-cranberry interactions (due to the inhibitory effect of flavonoids on cytochrome P450-mediated drug metabolism). The findings of the Cochrane Collaboration support the potential use of cranberry products in the prophylaxis of recurrent UTIs in young and middle-aged women. However, in light of the heterogeneity of clinical study designs and the lack of consensus regarding the dosage regimen and formulation to use, cranberry products cannot be recommended for the prophylaxis of recurrent UTIs at this time.

The Scourge of Sarcoptes: Oral Ivermectin for Scabies

OBJECTIVE

To review the use of the oral antiparasitic ivermectin in the treatment of scabies, with an emphasis on its use in the elderly and in long-term care settings.

DATA SOURCE

A MEDLINE/PUBMED search was conducted to identify pertinent studies, case reports, letters, and reviews in the English language. All articles published from 1980 to October 2003 were reviewed. Additional references were obtained from the bibliographies of these articles.

STUDY SELECTION

All studies evaluating ivermectin in the context of scabies mite infestation.

DATA SYNTHESIS

The semisynthetic macrocyclic lactone ivermectin has been available since the early 1980s as a broad-spectrum antiparasitic agent in animals and humans. This agent, which works by suppressing motor nerve conduction leading to parasite paralysis and death, was first used in ectoparasitic diseases (i.e., those caused by lice and mites) shortly after commercial introduction. A large body of literature, mainly uncontrolled case reports and series, has since evolved. However, these reports and results of the small number of placebo- and/or active-controlled studies have demonstrated the favorable response of both classic and crusted scabies to single- and multiple-dose oral ivermectin. Adverse reactions to the drug are uncommon, with the exception of a transient, new onset, or mild increase in existing pruritus soon after drug ingestion, which is thought to be a hypersensitivity reaction to dead mites and/or their products.

CONCLUSION

Oral ivermectin may prove to be a time- and labor-saving alternative to topical scabicide treatments, especially in the institutional setting where labor shortages make the management of scabies outbreaks a true challenge. However, the use of this agent does not change the need to decontaminate the environment (clothing, bedding, bed clothes, and, in selected cases, floors and walls) in order to truncate an outbreak and prevent reinfestation.

Daptomycin: The First Approved Lipopeptide Antimicrobial

OBJECTIVE

To review the literature concerning the first Food and Drug Administration-approved lipopeptide antimicrobial, daptomycin.

DATA SOURCES

A PUBMED search was conducted to identify pertinent English-language journal articles between 1985 and November 2003, and additional references were obtained from the bibliographies of these articles. Abstracts from the Interscience Conference on Antimicrobial Agents and Chemotherapy meetings from 1985 through 2003 also were reviewed.

STUDY SELECTION

All studies evaluating any aspect of daptomycin.

DATA SYNTHESIS

Daptomycin is a semisynthetic lipopeptide, the first such antimicrobial agent to reach the marketplace. Its mechanism of action differs from that of the related agent vancomycin in that much of its effect is not because of inhibition of peptidoglycan biosynthesis, but instead is a result of alterations in cell-membrane electrical charge and transport. It exhibits a broad spectrum of activity against gram-positive aerobes and anaerobes, including methicillin-, penicillin-, aminoglycoside-, and vancomycin-resistant strains. In subjects with normal renal function, the terminal disposition half-life is about 7 to 10 hours. It is principally eliminated as unchanged drug in the urine. Available clinical trial data demonstrate efficacy in complicated skin and skin-structure infections resulting from susceptible gram-positive pathogens, but not in pneumonia. The principal adverse event of concern, although rare, is myotoxicity, manifested by muscle pain and/or weakness and elevated serum creatine phosphokinase (CPK) concentrations. The approved dosage regimen is 4 mg/kg intravenously over 30 minutes once daily for 7 days to 14 days. Studies are underway evaluating doses of up to 8 mg/kg once daily.

CONCLUSIONS

Daptomycin, the first lipopeptide antimicrobial to be marketed, exhibits activity against multiresistant gram-positive pathogens, including linezolid- and quinupristindalfopristin-resistant strains. As such, it is a potentially valuable agent to treat infections resulting from such pathogens. To preserve its utility, it should not be used indiscriminately for infections resulting from pathogens sensitive to other antimicrobials. It is probably best used with restricted access and used only for multiresistant gram-positive pathogens where alternative agents cannot be employed. If used, careful monitoring for the signs and symptoms of myotoxicity, including obtaining weekly serum CPK levels, is mandatory. In addition, bacterial sensitivities to this agent should be prospectively monitored by national antimicrobial surveillance programs like SENTRY, TRUST, and LIBRA.

Darifenacin: Another Antimuscarinic for Overactive Bladder

OBJECTIVE

To review darifenacin, a new anticholinergic for overactive bladder, approved in December 2004 by the U.S. Food and Drug Administration.

DATA SOURCE

A MEDLINE/PUBMED search was conducted to identify pertinent studies in the English language. In addition, proceedings of meetings of the International Continence Society, European Association of Urology, American Urological Association, and American College of Obstetrics and Gynecology were reviewed for relevant abstracts. Additional references were obtained from the bibliographies of these sources. Data over the time period of 1986 through September 2004 were reviewed.

STUDY SELECTION

All studies evaluating any aspect of darifenacin in vitro or in vivo in animals or humans.

DATA SYNTHESIS

Preclinical studies demonstrated that darifenacin was an antagonist at muscarinic cholinergic M1, M3, and M5 receptors. On the basis of preclinical data, darifenacin was felt to be a "uroselective" antimuscarinic. Darifenacin is extensively metabolized, with urinary excretion of parent compound being less than 10%. Darifenacin, dosed as 7.5 or 15 mg once daily, is significantly superior to placebo in reducing the numbers of micturitions, urges, incontinence episodes, and urge severity and increasing the warning time and volume per micturition. No active-controlled trial data are available. The most problematic adverse effects of darifenacin are the anticholinergic effects of dry mouth and constipation.

CONCLUSION

Although promising in preclinical studies, the "uroselectivity" of the anticholinergic activity of darifenacin has not been confirmed in clinical trials. No comparative data with marketed (for overactive bladder) anticholinergics are available. On the basis of available data, darifenacin does not appear to be a substantial advance upon existing anticholinergics in the management of overactive bladder.

Use of oral oxymorphone in the elderly

OBJECTIVE

To review the pharmacodynamics, pharmacokinetics, efficacy, tolerability, dosing, and role of oral oxymorphone immediate-release (IR) and extended-release (ER).

DATA SOURCE

A MEDLINE/PUBMED search (1970 to September 2006) of English language studies. Additional references were obtained from their bibliographies.

STUDY SELECTION

All human studies of oxymorphone were reviewed.

DATA SYNTHESIS

Oral oxymorphone IR/ER tablet formulations were approved in June 2006. Oxymorphone, a semi-synthetic -opioid receptor agonist structurally similar to hydromorphone, has an oral bioavailability of approximately 10%. Oxymorphone is extensively metabolized to oxymorphone-3-glucuronide and the active 6-hydroxyoxymorphone. Rapid clearance mandates every four- to six-hour dosing (IR) and every 12-hour dosing (ER). Hepatic impairment, renal impairment, and aging enhance systemic exposure. Oxymorphone IR was superior to placebo and oxycodone IR (acute pain studies). Oxymorphone ER was superior to placebo and equivalent to oxycodone CR and morphine CR (one acute and five chronic pain studies). Oxymorphone exhibits the expected opioid side effects, being comparable to oxycodone and morphine in clinical trials. Coadministration with ethanol causes "dose-dumping" (ER) and increases intersubject variability in drug absorption. Oxymorphone IR is indicated for the relief of moderate-to-severe pain, while oxymorphone ER is indicated for persistent pain. Initial doses (opioid-naïve) are 10 mg to 20 mg every 4 to 6 hours (IR) and 5 mg every 12 hours (ER). Dosage adjustment is recommended in mild hepatic impairment (Child-Pugh class A), renal impairment (creatinine clearance below 50 mL/min), and in the elderly.

CONCLUSION

Oxymorphone is the newest oral opioid to enter a crowded marketplace now totaling 12 Schedule 2 opioids. It does not appear to have any unique assets or liabilities and should be considered as one of many oral opioids for the management of acute and persistent pain of moderate-to-severe intensity.

Drug forecast - the peptide deformylase inhibitors as antibacterial agents

The relatively rapid development of microbial resistance after the entry of every new antimicrobial into the marketplace necessitates a constant supply of new agents to maintain effective pharmacotherapy. Despite extensive efforts to identify novel lead compounds from molecular targets, only the peptide deformylase inhibitors (PDIs) have shown any real promise, with some advancing to phase I human trials. Bacterial peptide deformylase, which catalyzes the removal of the N-formyl group from N-terminal methionine following translation, is essential for bacterial protein synthesis, growth, and survival. The majority of PDIs are pseudopeptide hydroxamic acids and two of these (IV BB-83698 and oral NVP LBM-415) entered phase I human trials. However, agents to the present have suffered from major potential liabilities. Their in vitro activity has been limited to gram-positive aerobes and some anaerobes and has been quite modest against the majority of such species (MIC(90) values ranging from 1-8 mg/L). They have exerted bacteriostatic, not bacteriocidal, activity, thus reducing their potential usefulness in the management of serious infections in the immunocompromised. The relative ease with which microorganisms have been able to develop resistance and the multiple available mechanisms of resistance (mutations in fmt, defB, folD genes; AcrAB/TolC efflux pump; overexpression of peptide deformylase) are worrisome. These could portend a short timespan of efficacy after marketing. Despite these current liabilities, further pursuit of more potent and broader spectrum PDIs which are less susceptible to bacterial mechanisms of resistance is still warranted.

Drug forecast--solifenacin: an investigational anticholinergic for overactive bladder

OBJECTIVE

To review a new anticholinergic for overactive bladder undergoing review by the U.S. Food and Drug Administration, solifenacin.

DATA SOURCE

A MEDLINE/PUBMED search was conducted to identify pertinent studies in the English language. In addition, proceedings of meetings of the Incontinence Society, European Association of Urology, American Urological Association, and American College of Obstetrics and Gynecology were reviewed for relevant abstracts. Additional references were obtained from the bibliographies of these sources. Data over the time period of 1986 through October 2003 were reviewed.

STUDY SELECTION

All studies evaluating any aspect of solifenacin in animals and humans.

DATA SYNTHESIS

Preclinical studies demonstrated that solifenacin was an antagonist at muscarinic cholinergic M1, M2, and M3 receptors. On the basis of comparative preclinical studies evaluating the effects of solifenacin and oxybutynin on guinea pig detrusor muscle cells, mouse submandibular gland cells, and the intact rat, solifenacin was felt to be a "uroselective" antimuscarinic. Solifenacin is predominantly eliminated via metabolism, with urinary excretion of parent compound being less than 10%. Solifenacin, dosed once daily, is significantly superior to placebo in reducing the number of micturitions, urge episodes, and urge incontinence episodes per day and increasing the volume voided per micturition. In two active-controlled trials, solifenacin was at least equivalent to tolterodine in efficacy and tolerability. The most problematic adverse effects of solifenacin are the anticholinergic effects of dry mouth, blurred vision, and constipation.

CONCLUSION

Although promising in preclinical studies, the uroselectivity of the anticholinergic activity of solifenacin has not been validated in clinical trials. No comparative efficacy/tolerability data with oxybutynin are available. On the basis of available data, solifenacin does not appear to be a substantial advance upon existing anticholinergics in the management of overactive bladder.

Rasagiline (TVP-1012): a new selective monoamine oxidase inhibitor for Parkinson's disease

OBJECTIVE

This article reviews the chemistry, pharmacodynamics, pharmacokinetics, clinical efficacy, tolerability, drug-interaction potential, indications, dosing, and potential role of rasagiline mesylate, a new selective monoamine oxidase (MAO) type B (MAO-B) inhibitor, in the treatment of Parkinson's disease.

METHODS

A MEDLINE/PUBMED search (1986 through September 2006) was conducted to identify studies involving rasagiline written in English. Additional references were obtained from the bibliographies of these studies. All studies evaluating any aspect of rasagiline, including in vitro, in vivo (animal), and human studies, were reviewed.

RESULTS

Rasagiline mesylate was developed with the goal of producing a selective MAO-B inhibitor that is not metabolized to (presumed) toxic metabolites (eg, amphetamine and methamphetamine, which are byproducts of the metabolism of selegiline, another selective MAO-B inhibitor). In vitro and in vivo data have confirmed the drug's selectivity for MAO-B. Rasagiline is almost completely eliminated by oxidative metabolism (catalyzed by cytochrome P-450 [CYP] isozyme 1A2) followed by renal excretion of conjugated parent compound and metabolites. Drug clearance is sufficiently slow to allow once-daily dosing. Several studies have documented its efficacy as monotherapy for early-stage disease and as adjunctive therapy in L-dopa recipients with motor fluctuations. As monotherapy, rasagiline is well tolerated with an adverse-effect profile similar to that of placebo. As adjunctive therapy, it exhibits the expected adverse effects of dopamine excess, which can be ameliorated by reducing the L-dopa dosage. CYP1A2 inhibitors slow the elimination of rasagiline and mandate dosage reduction. Hepatic impairment has an analogous effect. The recommended dosage regimens for monotherapy and adjunctive therapy are 1 and 0.5 mg PO QD, respectively.

CONCLUSIONS

Despite the well-documented selectivity of rasagiline, the manufacturer recommends virtually all of the dietary (vis-à-vis tyramine) and drug restrictions of the nonselective MAO inhibitors. Although useful, selective MAO-B inhibitors have a limited role in Parkinson's disease. Of greater interest is the potential neuroprotective effect of rasagiline and its major metabolite, 1(R)-aminoindan, which may have great utility in a wide variety of neurodegenerative disorders of aging. In addition, bifunctional molecules combining selective MAO-B inhibition (based on the active moiety of rasagiline) with acetylcholinesterase inhibition or iron chelation may eventually be useful in Alzheimer's disease.

Ibandronate, an experimental intravenous bisphosphonate for osteoporosis, bone metastases, and hypercalcemia of malignancy

Ibandronate is an experimental intravenous bisphosphonate under study for the prevention or treatment of osteoporosis and skeletal complications of bone metastases, as well as hypercalcemia of malignancy. To review the data on this drug, PubMed/MEDLINE was searched for pertinent studies in English; data from January 1986-October 2005 were reviewed. In preclinical studies, ibandronate was an extremely potent bisphosphonate compared with its predecessors and was active in all animal models of human postmenopausal and corticosteroid-associated osteoporosis. Similar to other bisphosphonates, ibandronate exhibits antitumor activity and prevents or reduces bone metastases. Forty to fifty percent of the dose is bound to bone; renal clearance of unchanged drug accounts for 70% of total body clearance. Early clinical trials demonstrated efficacy and tolerability of intravenous ibandronate in the prevention or treatment of postmenopausal and corticosteroid-associated osteoporosis when administered once every 3 months. Intravenous ibandronate also reduces skeletal complications of bone metastases, including pain, although the cumulative dose used is much higher than that used in osteoporosis, as the drug is administered every 3-4 weeks. Single doses of intravenous ibandronate are probably also effective in the treatment of hypercalcemia of malignancy. The major tolerability issue with intravenous bisphosphonates is renal safety, thus the drugs generally require infusion (e.g., 0.25 hr for zoledronic acid, 2-24 hrs for pamidronate). However, intravenous ibandronate can be administered by bolus injection over a few minutes without an elevated risk of nephrotoxicity. The experimental intravenous dosage is 2 mg every 3 months for treatment or prevention of osteoporosis, and 2-6 mg every 3-4 weeks or in a single dose for treatment of bone metastases or hypercalcemia of malignancy, respectively. Ibandronate can be used in the presence of severe renal impairment with proper dosage adjustment. The drug will be an interesting addition to the available drugs for osteoporosis, bone metastases, and hypercalcemia of malignancy. Studies of intravenous ibandronate as an adjunctive treatment for cancers that tend to metastasize to bone are under way. Whether intravenous ibandronate will be a therapeutic advance is best answered by randomized, controlled trials. These are ongoing and should provide data with which to make better-informed choices concerning intravenous bisphosphonates.

Ibandronate: a new oral bisphosphonate for postmenopausal osteoporosis

OBJECTIVE

To review a new oral bisphosphonate, ibandronate, recently approved by the U.S. Food and Drug Administration for the treatment and prevention of postmenopausal osteoporosis.

DATA SOURCE

A MEDLINE/PUBMED search was conducted to identify pertinent studies in the English language. Additional references were obtained from the bibliographies of these studies. Data over the time period of 1986 through July 2005 were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All studies evaluating any aspect of ibandronate in animals and humans. Studies in humans focused on the oral drug formulation.

DATA SYNTHESIS

Preclinical studies established that ibandronate was an extremely potent bisphosphonate compared with its predecessors and that it was active in all animal models of human postmenopausal and corticosteroid-associated osteoporosis. Similar to other selected bisphosphonates, preclinical studies also showed that ibandronate exhibits antitumor activity and prevents and/or reduces bone metastases. As with other oral bisphosphonates, oral bioavailability is very poor (less than 1%) and substantially reduced by administration with or proximal to cations (e.g., food, antacids, mineral supplements). Clinical trials have demonstrated the efficacy and tolerability of oral ibandronate in the treatment and prevention of postmenopausal osteoporosis when administered once daily, once weekly, and even once monthly. Ibandronate also reduces the skeletal complications of bone metastases in patients with cancer, including pain, although the dosage used is much higher than that used in osteoporosis. As with other bisphosphonates, the major tolerability issue with ibandronate is upper gastrointestinal (GI) distress (dyspepsia, pain, esophagitis, esophageal and gastric ulcers). The dosage regimen for the treatment or prevention of postmenopausal osteoporosis (the only currently approved use in the United States) is 2.5 mg once a day or 150 mg once monthly (on the same date each month). Ibandronate should not be used in the presence of severe renal impairment (creatinine clearance below 30 mL/min). The usual complex administration instructions for other oral bisphosphonates apply to ibandronate as well.

CONCLUSION

Oral ibandronate is an interesting addition to the therapeutic armamentarium for osteoporosis and cancer metastatic to bone. In fact, studies of ibandronate as an adjunctive treatment for cancers with a predilection to metastasize to bone are under way. Ibandronate has taken advantage of a complex pharmacodynamic profile in which its antiresorptive activity is independent of the frequency of dosing provided that a minimum dose-per-unit time is exceeded. Studies with every three-month dosing (and even less frequently) are under way. Whether or not the less frequent dosing of oral ibandronate will translate into a therapeutic advantage over older oral agents such as alendronate and risedronate is open to speculation. This is a difficult question to answer in the absence of head-to-head randomized controlled trials (RCTs). Older agents are still preferred until RCTs demonstrate that ibandronate is as safe and effective as these older agents.

Pregabalin in neuropathic pain: a more "pharmaceutically elegant" gabapentin?

OBJECTIVE

This article reviews the available information on pregabalin, a new anticonvulsant for peripheral neuropathic pain. Pregabalin was provisionally approved by the US Food and Drug Administration in December 2004 and was granted final approval after controlled substance scheduling (Schedule V) by the US Drug Enforcement Agency in August 2005.

METHODS

A MEDLINE search (1986-August 2005) was conducted to identify pertinent studies in the English language. The search terms included pregabalin, PD144723, CI-1008, gabapentin, and neuropathic pain. Additional references were obtained from the bibliographies of identified articles. All studies that evaluated any aspect of pregabalin in vitro or in vivo in animals or humans were included, with a focus on data relevant to older adults.

RESULTS

In preclinical studies, pregabalin, a structural congener of gabapentin, exhibited antinociceptive activity in animal models of neuropathic and inflammatory pain. Unlike gabapentin, pregabalin was well absorbed (> 90%), and its absorption was dose independent. Like gabapentin, pregabalin was predominantly excreted unchanged in the urine (> or = 98%). Dosed at 50 to 200 mg TID, pregabalin was superior to placebo in relieving pain and improving sleep and health-related quality of life in patients with diabetic peripheral neuropathy and postherpetic neuralgia (P < 0.001-P < 0.049). No active-controlled trials were available. The most problematic adverse events associated with pregabalin were dizziness and somnolence (21%-26%).

CONCLUSIONS

In the absence of active-controlled clinical trials and geriatric-specific efficacy/tolerability data, the place of pregabalin in the analgesic armamentarium for the elderly is unclear. Because pregabalin is a Schedule V controlled substance, its utility is not compromised by substantial limitation of access or the need for extra steps in prescribing. However, abuse potential is a consideration, and utilization should be carefully monitored, particularly in patients with a past or current history of substance abuse. The improved pharmacokinetic profile of pregabalin relative to gabapentin is manifested in linear and dose-independent absorption and a narrow therapeutic dosing range. However, pregabalin still requires multiple administrations per day, and daily doses > 150 mg/d require dose titration. The relatively high frequency of central nervous system adverse events, particularly dizziness and somnolence, is a concern in the elderly. Time and further experience should clarify the role of this agent.

Duloxetine for management of stress urinary incontinence

OBJECTIVE

The aim of this article was to review data regarding the efficacy and tolerability of duloxetine, a selective serotonin (5-HT)-norepinephrine (NE) reuptake inhibitor that has received US Food and Drug Administration marketing approval for the treatment of major depressive disorder and painful diabetic neuropathy, and that has been investigated as a treatment for stress urinary incontinence.

METHODS

A MEDLINE/PubMed search was conducted to identify English-language study reports. In addition, proceedings of meetings of the International Continence Society, European Association of Urology, American Urological Association, and American College of Obstetrics and Gynecology were reviewed for relevant abstracts (search terms included duloxetine, thiophenes, serotonin uptake inhibitors, adrenergic uptake inhibitors, and stress urinary incontinence). Additional references were obtained from the bibliographies of these sources. Data for the period from 1986 through January 2005 were reviewed.

RESULTS

All in vitro and in vivo studies of duloxetine were included. Because both 5-HT and NE are involved in the maintenance of urinary continence, duloxetine may have a role in the treatment of urinary incontinence. Duloxetine is primarily eliminated via metabolism, with < 1% of the parent compound excreted via urine. Duloxetine QD or BID has been found to be significantly superior to placebo in reducing incontinence episode frequency (P < 0.001 to P < 0.05), increasing the interval between micturitions (P < 0.001 to P = 0.004), and improving the condition as measured by patient self-report (P < 0.001 to P = 0.028) and incontinence quality-of-life scores (P = 0.002 to P = 0.03). The most problematic adverse events are nausea, dry mouth, constipation, dizziness, and insomnia.

CONCLUSIONS

Although statistically superior to placebo in efficacy trials, the clinical effects of duloxetine therapy on incontinence are small, suggesting that any benefits to the patient would be modest and must be weighed against the drug's adverse event profile. No comparative efficacy/tolerability data with alpha-receptor agonists (eg, pseudoephedrine) are available. On the basis of available data, duloxetine is a modest, but welcome, advance in the pharmacotherapeutic management of stress urinary incontinence.

Oxcarbazepine, topiramate, zonisamide, and levetiracetam: potential use in neuropathic pain

BACKGROUND

Oxcarbazepine, topiramate, zonisamide, and levetiracetam are the antiepileptic drugs (AEDs) most recently approved by the US Food and Drug Administration. Based on the experience with carbamazepine, gabapentin, and lamotrigine, these newer AEDs are being investigated for the management of neuropathic pain.

OBJECTIVE

This article reviews preclinical and clinical data on the efficacy and tolerability of these 4 AEDs in the management of neuropathic pain, as well as the pharmacokinetics, drug-interaction potential, adverse effects, and dosing of these agents, with an emphasis on their use in older individuals.

METHODS

Relevant studies were identified through a MEDLINE search of the Englidh-language literature published between 1986 and May 2003, a review of the reference lists of identified articles, and abstracts from the annual meetings of the American Academy of Neurology (1986-2002) and the 2003 Annual Meeting of the American Pain Society. Search terms were oxcarbazepine, topiramate, zonisamide, and levetiracetam.

RESULTS

Oxcarbazepine and topiramate have been effective in animal models of neuropathic pain. Thirty-four publications on the efficacy and tolerability of the 4 agents were identified (25 case reports/case series, 6 randomized parallel-group studies, and 3 randomized crossover studies). The 9 randomized studies were restricted to oxcarbazepine and topiramate, and 23 (68%) publications were available in abstract form only. These preliminary data suggest that the 4 newer AEDs may be useful in a wide variety of neuropathic pain syndromes; however, additional data, including full-length peer-reviewed reports, are necessary before their true analgesic potential in neuropathic pain can be determined. All 4 agents have pharmacodynamic interactions with other psychotherapeutic drugs, potentiating adverse central nervous system events such as sedation. With the exception of levetiracetam, these drugs also have pharmacokinetic interactions with other drugs, although to a somewhat lesser extent than carbamazepine. These agents have some unique adverse effects not frequently monitored by clinicians, such as hyponatremia, nephrolithiasis, acute myopia with secondary angle-closure glaucoma, and weight loss.

CONCLUSIONS

Based on preliminary data, oxcarbazepine, topiramate, zonisamide, and levetiracetam may be useful in the treatment of a wide variety of neuropathic pain syndromes, although full publication of the results of controlled trials is awaited. These agents are associated with specific adverse effects not commonly monitored by clinicians. Of the 4, levetiracetam appears to be easiest to use (ie, no need for dose adjustment in organ dysfunction, no need for laboratory monitoring) and best tolerated, and has not been associated with the unique toxicities seen with oxcarbazepine, topiramate, and zonisamide. The ultimate role of these agents in the therapeutic armamentarium against pain requires further research and experience. In the interim, these 4 agents should be used to treat neuropathic pain in the elderly only when carbamazepine, gabapentin, or lamotrigine cannot be used or when the response to the aforementioned agents is suboptimal.

Clinical pharmacokinetics of drugs used to treat urge incontinence

Urge incontinence (also known as overactive bladder) is a common form of urinary incontinence, occurring alone or as a component of mixed urinary incontinence, frequently together with stress incontinence. Because of the pathophysiology of urge incontinence, anticholinergic/antispasmodic agents form the cornerstone of therapy. Unfortunately, the pharmacological activity of these agents is not limited to the urinary tract, leading to systemic adverse effects that often promote nonadherence. Although the pharmacokinetics of flavoxate, propantheline, scopolamine, imipramine/desipramine, trospium chloride and propiverine are also reviewed here, only for oxybutynin and tolterodine are there adequate efficacy/tolerability data to support their use in urge incontinence. Oxybutynin is poorly absorbed orally (2-11% for the immediate-release tablet formulation). Controlled-release oral formulations significantly prolong the time to peak plasma concentration and reduce the degree of fluctuation around the average concentration. Significant absorption occurs after intravesical (bladder) and transdermal administration, although concentrations of the active N-desethyl metabolite are lower after transdermal compared with oral administration, possibly improving tolerability. Food has been found to significantly affect the absorption of one of the controlled-release formulations of oxybutynin, enhancing the rate of drug release. Oxybutynin is extensively metabolised, principally via N-demethylation mediated by the cytochrome P450 (CYP) 3A isozyme. The pharmacokinetics of tolterodine are dependent in large part on the pharmacogenomics of the CYP2D6 and 3A4 isozymes. In an unselected population, oral bioavailability of tolterodine ranges from 10% to 74% (mean 33%) whereas in CYP2D6 extensive metabolisers and poor metabolisers mean bioavailabilities are 26% and 91%, respectively. Tolterodine is metabolised via CYP2D6 to the active metabolite 5-hydroxymethyl-tolterodine and via CYP3A to N-dealkylated metabolites. Urinary excretion of parent compound plays a minor role in drug disposition. Drug effect is based upon the unbound concentration of the so-called 'active moiety' (sum of tolterodine + 5-hydroxymethyl-tolterodine). Terminal disposition half-lives of tolterodine and 5-hydroxymethyl-tolterodine (in CYP2D6 extensive metabolisers) are 2-3 and 3-4 hours, respectively. Coadministration of antacid essentially converts the extended-release formulation into an immediate-release formulation. Knowledge of the pharmacokinetics of these agents may improve the treatment of urge incontinence by allowing the identification of individuals at high risk for toxicity with 'usual' dosages. In addition, the use of alternative formulations (controlled-release oral, transdermal) may also facilitate adherence, not only by reducing the frequency of drug administration but also by enhancing tolerability by altering the proportions of parent compound and active metabolite in the blood.

Extended-release alfuzosin hydrochloride: A new alpha-adrenergic receptor antagonist for symptomatic benign prostatic hyperplasia

BACKGROUND

Extended-release (ER) alfuzosin hydrochloride is the most recently approved alpha-adrenergic receptor antagonist (AARA) for the management of symptomatic benign prostatic hyperplasia (BPH). Although new to the United States, alfuzosin has been available in immediate-release (IR) and sustained-release (SR) formulations in other countries for many years.

OBJECTIVE

This article reviews data on the pharmacodynamics, pharmacokinetics, efficacy, tolerability, drug-interaction potential, and dosing of alfuzosin ER.

METHODS

Relevant articles were identified through MEDLINE, EMBASE, and International Pharmaceutical Abstracts searches of the English-language literature published between 1986 and September 2003 using the terms alfuzosin, alpha-adrenergic receptor antagonists, and quinazolines. The reference lists of identified articles were also searched, as were abstracts from annual meetings of the American Urological Association for the past 5 years. Data regarding the ER formulation were emphasized, and data involving the IR/SR formulations were included only when data for the ER formulation were not available or as needed for clarification.

RESULTS

In comparative trials with its IR counterpart (alfuzosin ER 10 mg QD vs alfuzosin IR 2.5 mg TID), alfuzosin ER was an equieffective once-daily AARA. No comparative trials of alfuzosin ER with the SR (BID) formulation or with other AARAs were identified. Food has been found to exert a clinically important effect by enhancing the bioavailability of the ER formulation; thus, the drug should be taken on a full stomach. Hepatic impairment has been found to significantly delay the elimination of alfuzosin IF, which constitutes a contraindication to use of the ER formulation. Renal impairment does not appear to exert clinically important effects on the pharmacokinetics of alfuzosin ER. Adverse events with alfuzosin ER include dizziness, upper respiratory tract infection, headache, and fatigue, with hypotension and syncope reported rarely. Concurrent use of inhibitors of the cytochrome P450 3A4 isozyme (eg, ketoconazole, diltiazem, cimetidine, atenolol) can significantly elevate serum concentrations of alfuzosin and enhance its pharmacodynamic effects.

CONCLUSIONS

In the absence of direct head-to-head comparative trials, the role of alfuzosin ER in the management of symptomatic BPH relative to that of other AARAs is unclear. Because the effect size (drug response minus placebo response) of alfuzosin ER is comparable to that of other AARAs, marked differences in efficacy are unlikely. Extrapolating from direct comparative trials between these agents and alfuzosin IR/SR, alfuzosin ER would be expected to have better cardiovascular tolerability (eg, in terms of dizziness and orthostasis) than prazosin, terazosin, or doxazosin, and to have similar tolerability to tamsulosin. However, the existing data do not suggest that alfuzosin ER is likely to represent a significant advance over tamsulosin.

Oritavancin and Tigecycline: Investigational Antimicrobials for Multidrug-Resistant Bacteria

The advent of multidrug-resistant gram-positive aerobes such as Staphylococcus aureus, Streptococcus pneumoniae, and the enterococci, which are resistant to beta-lactams, vancomycin, and a host of other commonly used antimicrobials, has complicated our approach to antibiotic therapy. Despite marketing of the first oxazolidinone, linezolid, and the streptogramin combination, quinupristin-dalfopristin, an urgent need exists for more agents to combat these pathogens. Two such agents, the glycopeptide oritavancin (LY333328) and the glycylcycline tigecycline (GAR-936), are in phase III clinical trials. These agents, which require parenteral administration, exhibit substantial in vitro activity against a variety of gram-positive aerobes and anaerobes, including the multidrug-resistant organisms listed previously. Only tigecycline demonstrates useful activity against gram-negative organisms. Combination therapy of these agents with ampicillin or aminoglycosides frequently leads to synergistic in vitro activity against multidrug-resistant staphylococci and streptococci. These agents are also active in a variety of animal models of systemic and localized infections. Few published efficacy and tolerability data are available in humans. If controlled clinical trial data verify these agents' efficacy and tolerability, both drugs should become welcome additions to the available antimicrobials. However, restricting their use to the treatment of infections caused by bacteria resistant to other antimicrobials, especially multidrug-resistant staphylococci and streptococci, may prolong their clinical utility by retarding the development of resistance. Careful surveillance of bacterial sensitivity to these agents should be undertaken to assist clinicians in the decision whether or not to use these agents empirically to treat infections caused by suspected multidrug-resistant gram-positive pathogens.

Treatment of bacterial skin and skin structure infections

Bacterial skin and skin structure infections (SSSIs) are among the most frequently seen infectious entities in the community setting and occasionally in the institutional setting. A wide variety of SSSIs exist, with cellulitis, impetigo and folliculitis being the most common. Most SSSIs are caused by aerobic staphylococci and streptococci, with aerobic Gram-negative bacilli and anaerobes being involved in more complicated infections. Systemic therapy with a variety of beta-lactams, macrolides and lincosamides (clindamycin) have been the cornerstone of SSSI therapy for many years. With the exception of mupirocin, topical therapy occupies a small therapeutic niche. Despite the emergence of antimicrobial resistance among the pathogens most commonly associated with SSSIs (for example, Streptococcus pyogenes and macrolides; Staphylococcus aureus and methicillin, vancomycin, penicillin and mupirocin), few treatment failures have been reported. The newest antimicrobials reviewed herein (linezolid, quinupristin/dalfopristin, gatifloxacin, gemifloxacin and moxifloxacin) are not a significant improvement upon older agents in the treatment of SSSIs. Perhaps this assessment will change if the penetrance of the antimicrobial resistance patterns described above reach a critical threshold and clinical failures become more widespread.

Drug forecast: memantine, prototype of a new approach to treatment of dementia

OBJECTIVE

To review the first clinically useful N-methyl-D-aspartate (NMDA) inhibitor for the treatment of dementia, memantine.

DATA SOURCE

A MEDLINE/PUBMED search was conducted to identify pertinent studies, case reports, letters, and reviews in the English language. All articles published from 1950 to March 2003 were reviewed. Additional references were obtained from the bibliographies of these articles.

STUDY SELECTION

All studies evaluating any aspect of memantine in humans.

DATA SYNTHESIS

The excitatory amino acid neurotransmitter glutamate is felt to play a role in neuroinflammation and destruction of cholinergic neurons associated with dementia. Memantine is an NMDA receptor antagonist which partially blocks glutamatergic neurotransmission in the central nervous system (CNS). It is a selective, moderate affinity, noncompetitive receptor blocker that rapidly associates with and dissociates from the NMDA receptor. Memantine, that is usually dosed once or twice daily, is predominantly eliminated as unchanged drug via the renal route (renal clearance accounts for 90% of total body clearance). Use of memantine is associated with significant improvements in a number of cognitive, functional, and behavioral assessment scales used in the evaluation of cognition-enhancing drugs in dementia. Adverse effects of memantine are generally referable to the CNS and include depression, insomnia, akathisia, agitation, dizziness, drowsiness, restlessness, and hyperexcitability.

CONCLUSION

Although there is no cure for dementia, memantine may delay disease progression and improve functioning to a clinically significant extent. However, efficacy has not been consistent within trials and no comparative data with acetylcholinesterase inhibitors (AchEI) are available. In addition, there are no controlled data available regarding combination memantine-AchEI therapy. Further study data are awaited.

Update on fenofibrate

Fenofibrate is a fibric acid derivative that has been marketed since the mid-1970's (1998 in the United States). Its active metabolite, fenofibric acid, is responsible for the primary pharmacodynamic effects of the drug: reductions in total plasma cholesterol, low density lipoprotein cholesterol, triglycerides, and very low-density lipoprotein concentrations and increases in high-density lipoprotein cholesterol and apolipoproteins AI and AII concentrations. These effects are mediated by activation of peroxisome proliferator-activated receptor-alpha (PPAR(alpha)). The drug has broad spectrum utility, with documented efficacy in Fredrickson types IIa, IIb, III, IV, and V hyperlipidemias. Fenofibrate is well tolerated, with digestive and musculoskeletal side effects similar to those of other fibrates. Results of the initial cardiovascular morbidity/mortality outcomes study with fenofibrate (known as DAIS [Diabetes Atherosclerosis Intervention Study]) were encouraging vis-à-vis slowing of atherosclerotic progression in the coronary vasculature of type II diabetics. The results of other ongoing outcome trials are eagerly awaited. These results will help to establish the overall place of fenofibrate in the hypolipidemic armamentarium.

Trandolapril: a newer angiotensin-converting enzyme inhibitor

BACKGROUND

Trandolapril is a newer angiotensin-converting enzyme (ACE) inhibitor that is approved by the US Food and Drug Administration for the treatment of hypertension and for use in stable patients who have evidence of left ventricular (LV) systolic dysfunction or symptoms of chronic heart failure within the first 2 days after an acute myocardial infarction (AMI). The fixed-dose combination of trandolapril and verapamil extended release (ER) is approved for the treatment of hypertension only.

OBJECTIVE

The purpose of this article was to review the pharmacology, pharmacokinetics, clinical efficacy, and safety profile of trandolapril as monotherapy and in fixed-dose combination with verapamil ER.

METHODS

Relevant studies were identified through a MEDLINE/PubMed search of the English-language literature published between January 1983 and August 2002 and a review of the bibliographies of identified articles.

RESULTS

Trandolapril has a sufficient duration of inhibition of plasma ACE activity to allow once-daily dosing. It is converted by esterases to the active trandolaprilat metabolite, with mean terminal disposition half-lives of < 1 and approximately 75 hours for the prodrug and metabolite, respectively. In comparative trials in the management of hypertension, trandolapril 1 to 4 mg/d was statistically indistinguishable from or superior to captopril 100 mg/d, enalapril 10 or 20 mg/d, hydrochlorothiazide (HCTZ) 25 mg/d, nifedipine ER 30 or 40 mg/d, nitrendipine 20 mg/d, perindopril 4 mg/d, and verapamil ER 120 to 240 mg/d. In the Trandolapril Cardiac Evaluation, trandolapril also significantly reduced all-cause mortality, cardiovascular mortality, sudden death, and progression to severe chronic heart failure in patients with evidence of LV systolic dysfunction after AMI. In comparative trials in the management of hypertension, the combination of trandolapril 1 or 2 mg/d and verapamil ER 180 mg/d was statistically indistinguishable from or superior to the combinations of atenolol 50 or 100 mg/d plus chlorthalidone 12.5 or 25 mg/d, captopril 50 mg/d plus HCTZ 25 mg/d, lisinopril 20 mg/d plus HCTZ 12.5 mg/d, and metoprolol 100 mg/d plus HCTZ 12.5 mg/d. The most common adverse effects of trandolapril monotherapy in clinical trials of < or = 1 year's duration included cough, dizziness, and diarrhea (frequency < or = 1.9%). The most common adverse effects of trandolapril/verapamil ER therapy in clinical trials of < or = 1 year's duration included first-degree atrioventricular block, bradycardia, constipation, cough, diarrhea, dizziness, fatigue, and dyspnea (frequency < or = 4.6%). Based on the literature search, there are no published pharmacoeconomic evaluations of trandolapril alone or combined with verapamil ER in the US health care setting.

CONCLUSIONS

Based on the literature, trandolapril is a well-tolerated and effective antihypertensive agent, whether used alone or in combination with verapamil ER. These products may be valuable in patients with LV systolic dysfunction after AMI, although the combination product is approved for the management of hypertension only.

Update on gabapentin therapy of neuropathic pain

OBJECTIVE

To provide current information regarding the efficacy and tolerability of the anticonvulsant gabapentin in the management of neuropathic pain.

DATA SOURCES

A MEDLINE search was conducted to identify pertinent studies, case reports, letters, and reviews in the English language published from 1986 through October 2002. Additional references were obtained from the bibliographies of these articles.

STUDY SELECTION

All studies evaluating any aspect of use of gabapentin as an analgesic.

DATA SYNTHESIS

Numerous case reports and series (total N = 750) have suggested efficacy of gabapentin in daily doses of up to 3.6 g. Controlled trials in painful diabetic neuropathy, postherpetic neuralgia, and multiple sclerosis have confirmed the potential utility of this agent in a variety of neuropathic pain syndromes (total N = 511). Central nervous system side effects are of most concern with gabapentin. The absence of significant drug-drug interactions makes this agent a preferred treatment choice, as opposed to anticonvulsants such as carbamazepine or lamotrigine.

CONCLUSION

In human pain models using patients with neuropathic pain, gabapentin has been found effective against both spontaneous and evoked pain, and these effects are independent of the pain source. Gabapentin, in doses ranging up to 3.6 g/day, has demonstrated efficacy in a variety of neuropathic pain states, including those refractory to agents such as the tricyclic antidepressants (TCA) and other anticonvulsants. A major question today is whether gabapentin should be considered as first-line therapy (i.e., even before a trial of a TCA or carbamazepine) or as second-line therapy for individuals unresponsive to or intolerant of TCAs and/or carbamazepine.

Pneumococcal polysaccharide revaccination: immunoglobulin g seroconversion, persistence, and safety in frail, chronically ill older subjects

OBJECTIVES

To determine the 1-month postpneumococcal polysaccharide-revaccination immunoglobulin G (IgG) antibody response, its persistence at 1 year, and tolerability of revaccination in frail, chronically ill older nursing facility residents.

DESIGN

Prospective study conducted between December 1998 and July 2000.

SETTING

Six skilled nursing facilities in the Minneapolis-St. Paul, Minnesota, metropolitan area.

PARTICIPANTS

Sixty-seven subjects aged 65 and older having received primary vaccination with pneumococcal polysaccharide vaccine (PPV) at least 5 years before enrollment.

INTERVENTION

Revaccination with one dose of 23-valent PPV.

MEASUREMENTS

Adverse events and concentrations of seven individual pneumococcal polysaccharide type-specific IgG antibodies (against serotypes 4, 6B, 9V, 14, 18C, 19F, 23F) and their aggregate before and 1 and 12 months after revaccination.

RESULTS

A significant increase in all individual and aggregate median antibody concentrations over baseline was observed 1 month after revaccination. However, after 1 year, the increase remained significant only for serotypes 6B and 18C and the aggregate parameter. One month after revaccination, the mean increase in antibody concentration over baseline was significantly greater than 1.4-fold for six of the seven serotypes and the aggregate. However, the increase was not significantly greater than 1.4 at 1 year for any of the serotypes or the aggregate. Minor, self-limited localized adverse reactions and systemic reactions occurred in 11.3% of the subjects.

CONCLUSIONS

In frail, chronically ill older nursing facility residents, revaccination with 23-valent PPV at least 5 years after primary vaccination (whether primary vaccination occurred before or after age 65) is associated with a significant, albeit brief, immunological response for most of the serotypes tested. Revaccination was well tolerated.

A renaissance for fluoxetine in the management of depression in the elderly?

OBJECTIVE

To review the literature pertaining to the use of the selective serotonin reuptake inhibitor (SSRI) fluoxetine in the management of depression in elders.

DATA SOURCES

A MEDLINE search was conducted to identify pertinent studies, case reports, letters, and reviews in the English language. All articles published from 1986 to 2002 were reviewed. Additional references were obtained from bibliographies of those articles.

STUDY SELECTION

All studies evaluating any aspect of the use of fluoxetine in managing geriatric depression.

DATA SYNTHESIS

Pharmacokinetic studies have demonstrated that the potential for accumulation of fluoxetine and its active metabolite norfluoxetine with chronic dosing in elders is less than or equal to that in young individuals. Renal impairment, a frequent comorbidity of older age, has no significant effect on the pharmacokinetics of fluoxetine/norfluoxetine. In elders, the efficacy of fluoxetine is statistically indistinguishable from that of paroxetine, sertraline, fluvoxamine, and tricyclic antidepressants in controlled trials, as are the adverse event profiles of fluoxetine and other tested SSRIs. The drug interaction potential of fluoxetine is similar to that of fluvoxamine and paroxetine and greater than those of citalopram, escitalopram, and sertraline.

CONCLUSION

Available data support a reevaluation of the role of fluoxetine in the management of geriatric depression, especially in light of the recent marketing of a generic fluoxetine product that is priced much lower than competitor branded SSRIs. Further studies of fluoxetine use in geriatric depression using adequate numbers of patients are recommended.

Cefdinir: an advanced-generation, broad-spectrum oral cephalosporin

BACKGROUND

Cefdinir is an advanced-generation, broad-spectrum cephalosporin antimicrobial agent that has been approved for the treatment of community-acquired pneumonia, acute bacterial exacerbations of chronic bronchitis, acute maxillary sinusitis, pharyngitis/tonsillitis, acute bacterial otitis media, and uncomplicated skin and skin-structure infections in adult and pediatric patients.

OBJECTIVE

The purpose of this article was to review the in vitro antimicrobial activity, pharmacokinetics, clinical efficacy, safety, and potential role of cefdinir.

METHODS

Studies were identified by a MEDLINE search (January 1983-September 2001) of the English-language medical literature, a review of identified articles and their bibliographies, and a review of data on file with the manufacturer. Clinical efficacy data were selected from all published trials mentioning cefdinir. Information concerning in vitro susceptibility, safety, chemistry, and the pharmacokinetic profile of cefdinir also was reviewed.

RESULTS

Cefdinir has a broad spectrum of activity against many gram-negative and gram-positive aerobic organisms, including Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae, and Moraxella catarrhalis. Cefdinir is stable to hydrolysis by 13 of the common beta-lactamases. It is rapidly absorbed from the gastrointestinal tract (mean time to peak plasma concentration, 3 hours) and is almost entirely eliminated via renal clearance of unchanged drug. The terminal disposition half-life of cefdinir is approximately 1.5 hours. Efficacy has been demonstrated in 19 clinical trials in adults and children with upper and lower respiratory tract infections (eg, pharyngitis, sinusitis, acute otitis media, acute bronchitis, acute bacterial exacerbation of chronic bronchitis, community-acquired pneumonia), and skin and skin-structure infections. The adverse-event profile is similar to that of comparator agents, although in 4 adult and adolescent studies and 1 adult study, diarrhea occurred significantly more frequently in cefdinir recipients than in recipients of penicillin V, cephalexin, cefaclor, and cefprozil.

CONCLUSIONS

Cefdinir is an alternative to other antimicrobial agents and can be dosed once or twice daily for the treatment of upper and lower respiratory tract infections and skin and skin-structure infections. Similar to other oral expanded-spectrum cephalosporins, cefdinir has activity against common pathogens of the respiratory tract and skin and is stable in the presence of selected beta-lactamases. The clinical choice of an oral expanded-spectrum cephalosporin will be based on patient acceptance, frequency of administration, and cost.