Clinical economics review: gastrointestinal complications of non-steroidal anti-inflammatory drugs

Clinical pharmacokinetics of the cyclooxygenase inhibiting nitric oxide donator (CINOD) AZD3582

The clinical pharmacokinetics of the COX-inhibiting nitric oxide donator (CINOD) AZD3582 and its metabolites, including naproxen, nitric oxide and nitrate, are summarized. AZD3582 has low aqueous solubility, moderate and passive intestinal permeability and is degraded by intestinal esterases. Its oral bioavailability (F) appears to be maximally a few per cent, and increases by several-fold after food intake. Ninety-four per cent or more of an AZD3582 dose is absorbed, of which at least 9–20% appears to be taken up as intact substance. AZD3582 has a predicted plasma protein binding degree of ∼ 0.1%, a half-life (t½) of 3 to 10 h and does not accumulate after repeated once- and twice-daily dosing. In patients AZD3582 does not provide a significantly better gastrointestinal (GI) side-effect profile than the highly permeable and locally irritating naproxen. Possible reasons for this include considerable GI uptake as naproxen, limited duration and extent of nitric oxide donation in the GI mucosa and the circulation, tolerance development (involving auto-inhibition of nitric oxide catalysing enzymes) and mucosal damage caused by nitric oxide. Blood pressure data suggest that nitric oxide is mainly donated within 3h. The uptake of naproxen is slightly slower and lower (≥ 94% relative GI uptake and 80–85% relative F) after AZD3582 administration compared with naproxen dosing. The naproxen t½ and trough steady-state concentrations after AZD3582 and naproxen dosing are similar. The average systemic nitrate exposure is approximately doubled after dosing of 375 to 750 mg AZD3582 twice daily.

Dose-effect comparisons of the CINOD AZD3582 and naproxen on upper gastrointestinal tract mucosal injury in healthy subjects

OBJECTIVE

The objective of this endoscopic study was to compare the effects on the gastroduodenal mucosa of healthy volunteers of different doses and dosing regimens of AZD3582, a cyclooxygenase-inhibiting nitric oxide donator (CINOD), with equimolar doses of naproxen.

MATERIAL AND METHODS

Healthy volunteers were enrolled in a single-centre, randomized, double-blind, crossover trial consisting of two 12-day treatment periods and employing six sequences. The groups were: AZD3582 750 mg daily versus 375 mg twice daily (n=25), AZD3582 375 mg twice daily versus 750 mg twice daily (n=25) and naproxen 250 mg twice daily versus 500 mg twice daily (n=25).

RESULTS

Gastroduodenal tract damage was similar with AZD3582 375 mg twice daily and 750 mg twice daily (mean number of erosions and ulcers+/-SD: 2.88+/-3.95 versus 3.08+/-2.80, respectively; p=0.824; 1 ulcer counted as 10 erosions). There was an indication of decreased gastroduodenal toxicity with AZD3582 750 mg daily compared with 375 mg twice daily (0.92+/-2.08 versus 2.71+/-4.75, respectively; p=0.068). Gastroduodenal toxicity was significantly lower with AZD3582 375 mg twice daily than with naproxen 250 mg twice daily (2.88+/-3.95 versus 6.16+/-9.36; p<0.05), and with AZD3582 750 mg twice daily versus naproxen 500 mg twice daily (3.08+/-2.80 versus 6.68+/-6.97; p<0.05). Equimolar twice-daily doses of AZD3582 and naproxen resulted in similar naproxen plasma levels and serum thromboxane B(2) inhibition.

CONCLUSIONS

AZD3582 has an improved gastroduodenal safety profile compared with equimolar doses of naproxen. The gastroduodenal effects of AZD3582 375 mg and AZD3582 750 mg twice daily are similar. A once-daily regimen of AZD3582 might be less gastrotoxic than a twice-daily regimen.

The Plastic Surgeon??s Guide to Drugs Affecting Hemostasis

The plastic surgeon is encountering an unprecedented population of aging individuals who both desire cosmetic or reconstructive surgery and may require the use of medications that alter hemostasis. The increasing use of anticoagulants and platelet inhibitors in particular can create challenges for the plastic surgeon. The purpose of this review is to familiarize the surgeon with the medications that can affect hemostasis and to suggest strategies for their use in the perioperative period. Specific case examples are presented.

Influence of age and cytochrome P450 2C9 genotype on the steady-state disposition of diclofenac and celecoxib

OBJECTIVE

To analyse the influence of age and cytochrome P450 (CYP) 2C9 genotype on the steady-state disposition of the standard NSAID diclofenac and the new COX-2 selective inhibitor celecoxib, both of which are metabolised by the polymorphically expressed CYP2C9.

DESIGN

Double-blind randomised crossover study under steady-state conditions.

SUBJECTS

12 young (age 32 +/- 5 years, bodyweight 71 +/- 12kg; mean +/- SD) and 12 elderly (68 +/- 2 years, 82 +/- 15kg) healthy, drug-free, nonsmoking Caucasians of both sexes.

METHODS

All subjects received oral celecoxib (200mg twice daily) and diclofenac (75mg twice daily) for 15 days separated by a drug-free interval of at least 3 weeks. Following the last morning dose, multiple blood samples were taken for 25 hours. Concentrations of celecoxib and diclofenac were measured by specific and sensitive high performance liquid chromatography. Identification of CYP2C9 genotype was performed by genomic DNA sequencing. Pharmacokinetic parameters for total and unbound drugs were individually analysed by noncompartmental techniques.

RESULTS

For diclofenac, area under the concentration-time curve over the dosage interval (AUC(tau)) was larger in young subjects (3.2 +/- 1.0 mg * h/L) than in older individuals (2.4 +/- 0.4 mg * h/L; p < 0.05). As the terminal half-life (t((1/2)Z)) was very similar in both groups (3.9 +/- 4.4 vs 3.5 +/- 3.3 hours), either less complete absorption in the elderly or their higher bodyweight could account for the difference. For celecoxib, AUC(tau) (5.8 +/- 1.7 vs 5.6 +/- 2.3 mg * h/L) and t((1/2)z) (11.8 +/- 8.7 vs 11.2 +/- 2.9 hours) were almost identical in young and older subjects. Plasma protein binding of both NSAIDs was unaffected by age, and apparent oral clearances for unbound drugs were not different between the two groups of healthy subjects. When considering the genotype of all individuals (CYP2C9*1/*1, n = 10; CYP2C9*1/*2, n = 6; CYP2C9*2/*2, n = 2; CYP2C9*1/*3, n = 4; CYP2C9*3/*3, n = 1), no association with any pharmacokinetic parameter of either drug was apparent. Moreover, there was no significant correlation between the AUC values of celecoxib and diclofenac.

CONCLUSIONS

Age and CYP2C9 genotype do not significantly affect the steady-state disposition of celecoxib and diclofenac. This would indicate that both drugs need no dosage reduction in the elderly (at least up to 75 years) and that, besides CYP2C9, additional CYP species contribute to the elimination of both agents.

Design and characterization of enzymosomes with surface-exposed superoxide dismutase

Superoxide dismutase (SOD) was chemically modified by covalent linkage of fatty acid chains to the accessible epsilon-amino groups of the enzyme. This acylation method gave rise to a different enzyme entity (Ac-SOD) as evidenced by different physicochemical properties such as octanol/water partition coefficient and isoelectric point (pI) as compared to SOD. Ac-SOD was incorporated in conventional and long-circulating liposomes (LCL) and characterized in terms of incorporation efficiency, protein to lipid ratio (Prot/Lip), enzymatic activity retention and zeta potential. The observation that Ac-SOD liposomes present enzymatic activity on their external surface indicates that these formulations can act independent of rate and extent of enzyme release as required in case of SOD liposomes. The decrease of superficial charge of liposomal formulations containing Ac-SOD, as compared to SOD liposomes, may be related to the negatively charged enzyme molecules localized on the liposome surface. The comparative characterization of Ac-SOD and SOD liposomal formulations evidenced that the two enzyme forms differ substantially regarding their intraliposomal location: SOD tends to be localized in the internal aqueous spaces, whereas Ac-SOD is expected to be localized in the lipid bilayers of the liposomes, partially buried into the outer surface and exposed to the external medium. These liposomal structures with surface-exposed SOD were designated as Ac-SOD enzymosomes. The properties of these enzymosomes may influence the therapeutic effect, as the release of the enzyme from extravasated vesicles is no longer a necessary requirement for achieving dismutating activity within the inflamed target site.

A pharmacoeconomic comparison of misoprostol/diclofenac with diclofenac

OBJECTIVES

To estimate the economic impact of misoprostol/diclofenac in a fixed combination tablet compared with diclofenac.

DESIGN

Cohort study with a prospectively constructed, population-based, record-linkage database containing details of exposure to all community dispensed NSAIDs and all admissions to hospital for upper gastrointestinal (GI) diagnoses. Costs associated with each study drug exposure were analysed using generalized linear models.

SETTING

The population of Tayside, Scotland.

SUBJECTS

Subjects aged 20 years and over who received misoprostol/diclofenac or any other NSAID between January 1989 and 31 December 1995.

MAIN OUTCOME MEASURES

Total costs for the number of days of exposure to diclofenac and misoprostol/diclofenac, plus costs of concomitant ulcer healing drug therapy plus endoscopy procedures plus costs of admissions to hospital for upper GI diagnoses.

RESULTS

The rate of hospitalization with gastrointestinal events was 30% higher among patients receiving diclofenac than that for patients receiving misoprostol/diclofenac. Among patients who received diclofenac and an ulcer-healing drug (UHD), the event rate was more than twice that for patients receiving misoprostol/diclofenac. In patients with a prior GI history, switching from diclofenac to misoprostol/diclofenac would reduce the costs of hospitalization. The resulting savings would more than offset the extra prescription costs. In patients without a prior GI history, the greatest potential saving would arise due to reduced use of UHDs and net savings would occur in subjects aged between 60 and 70 years of age or more.

CONCLUSION

Use of misoprostol/diclofenac instead of diclofenac can produce cost savings due to reduced hospitalization rates and decreased use of UHDs in subjects with a prior history of GI disease and in older subjects without prior GI disease. These findings have implications for the management of patients who require treatment with NSAIDs.

Healthcare resource utilisation and costs of treating NSAID-associated gastrointestinal toxicity. A multinational perspective

OBJECTIVE

The aim of the study was to perform an economic analysis of a new therapy in 11 countries (Australia, Belgium, Finland, France, Germany, Italy, The Netherlands, Spain, Sweden, Switzerland and the UK) to assess the cost of treating the gastrointestinal (GI) events associated with the use of nonsteroidal anti-inflammatory drugs in patients with osteoarthritis and rheumatoid arthritis.

METHODS

Estimates of GI event-related costs were based on the results of resource utilisation questionnaires. Resources required for the treatment and follow-up of GI events were identified and converted into costs from society and payer perspectives.

RESULTS

From the perspective of society, the total per-event cost of managing GI-related events varies from $US51 to $US772 for GI discomfort, from $US108 to $US1100 for anaemia, from $US145 to $US1200 for ulcer and from $US1923 to $US5473 for serious GI events requiring hospitalisation. From the payer perspective, the total per-event cost varies from $US47 to $US680 for GI discomfort, from $US144 to $US762 for anaemia, from $US229 to $US795 for ulcer and from $US1787 to $US6729 for serious GI events requiring hospitalisation. The total cost is driven by hospital expenses for those events requiring hospital admission. For GI discomfort, physician consultations are generally the cost driver, whereas for ulcer and anaemia, cost is primarily driven by the rate of endoscopy.

CONCLUSIONS

Costs associated with nonsteroidal anti-inflammatory drug-related GI events differ significantly across countries as a result of variations in resources consumed and price/tariff policies.

The costs of rheumatoid arthritis: an international long-term view

OBJECTIVES

To review the literature on the measurable direct and indirect costs of rheumatoid arthritis (RA) in industrialized countries from a societal perspective and to develop a template for international use.

METHODS

A literature search using MEDLINE and other sources identified 153 relevant published articles, press releases, and so forth on the costs of RA and rheumatism from the major Organization for Economic Cooperation and Development (OECD) countries in English and other languages. Sixty-eight publications provide some economic data for analysis and are included in the bibliography. Twelve publications provide sufficiently detailed and robust information for inclusion in country overview tables. The concept of varied costs at different disease stages measured by years since diagnosis and Health Assessment Questionnaire (HAQ) scores is used to guide rational decisions in the allocation of scarce health care resources.

RESULTS

Direct costs increase overproportionately during the course of the disease. The most important driver of direct costs is hospitalization, especially in moderate and severe RA. Costs of medication represent a comparatively small proportion of direct costs. Indirect costs caused by work disability can be substantially higher than direct costs, particularly in working-age patients. The total costs of RA to society, and the different cost components such as direct and indirect costs, are broadly comparable in industrialized countries by their order of magnitude. Major confounding factors for international comparison are different study methodologies and patient samples.

CONCLUSIONS

The cost template developed in this article can be used to estimate the likely costs of RA to society for industrialized countries. It probably will underestimate indirect costs because of their incomplete coverage in the studies examined. A long-term perspective is needed for chronic diseases such as RA to assess the future effects of early interventions. Treatment in the early stages of RA that effectively reduces long-term disability has the potential to save substantial costs to society.

Self-selection of the analgesic drug carprofen by lame broiler chickens

Lame and sound broilers, selected from commercial flocks, were trained to discriminate between different coloured feeds, one of which contained carprofen. The two feeds were then offered simultaneously and the birds were allowed to select their own diet from the two feeds. In an initial study to assess the most appropriate concentration of drug, the plasma concentrations of carprofen were linearly related to the birds' dietary intake. The walking ability of lame birds was also significantly improved in a dose-dependent manner and lame birds tended to consume more analgesic than sound birds. In a second study, in which only one concentration of analgesic was used, lame birds selected significantly more drugged feed than sound birds, and that as the severity of the lameness increased, lame birds consumed a significantly higher proportion of the drugged feed.

Prevention of non-steroidal anti-inflammatory drug-induced gastrointestinal mucosal injury: risk factors for serious complications

BACKGROUND

1-2% of all patients under non-steroidal anti-inflammatory drug therapy are exposed to serious upper gastrointestinal complications. The policy of prevention of non-steroidal anti-inflammatory drug-induced gastrointestinal mucosal injury by using misoprostol or suppressing acid secretion is still a matter of debate.

AIMS

To discuss the effectiveness of prophylaxis of a gastrointestinal complication during non-steroidal anti-inflammatory drug treatment, according to the number and relevance of risk factors.

PATIENTS

A total of 8.843 patients with rheumatoid arthritis, admitted to the widest prospective multicentre mega-trial, on 6-month complication prevention of non-steroidal anti-inflammatory drug-induced ulcers.

METHODS

The results are presented in terms of the number of patients to be treated (number needed to treat) in order to prevent one serious upper gastrointestinal complication, and corrected for the number of patients, that receiving the prophylaxis therapy, would lead to one additional withdrawal (number needed to harm).

RESULTS

The base-line risk for a complication strongly depended on the number and relevance of risk factors: history of peptic ulcer disease, of gastrointestinal bleeding, of cardiovascular disease, and age. In the general study population, the relative risk reduction of gastrointestinal complications with misoprostol was 40%: thus the number needed to treat to prevent 1 event was 250 in the experimental period (6 months) or 125 when normalized at one-year treatment (1 year number needed to treat]. When considering the prophylaxis gain in intermediate (risk 1-2%) or high risk subjects (patients with a probability of an event over 2%, for the presence of 1 important risk factor or multiple factors), the 1-year number needed to treat rapidly drops from about 100 to about 17. The number needed to harm for one withdrawal was 18. The number needed to treat corrected for withdrawals in order to avoid major complications rises from 125 to 132 in the general population of non-steroidal anti-inflammatory drug users; from 102 to 105 in subjects at intermediate risk, such as patients with history of cardiovascular disease; in the groups at high risk, from 26 to 27 (patients with history of peptic ulcer disease), and from 16 to 17 (patients with history of peptic ulcer disease, cardiovascular disease and aged over 65 years).

CONCLUSIONS

Patients at intermediate and high risk for complications from non-steroidal anti-inflammatory drug-induced ulcers should be considered for prophylaxis. In this group of patients, misoprostol prevention of severe complications is effective, and its clinical relevance similar to that of other preventive measures in medical practice.