Oxaprozin pharmacokinetics in the elderly

Design of predictive model to optimize the solubility of Oxaprozin as nonsteroidal anti-inflammatory drug

These days, many efforts have been made to increase and develop the solubility and bioavailability of novel therapeutic medicines. One of the most believable approaches is the operation of supercritical carbon dioxide fluid (SC-CO₂). This operation has been used as a unique method in pharmacology due to the brilliant positive points such as colorless nature, cost-effectives, and environmentally friendly. This research project is aimed to mathematically calculate the solubility of Oxaprozin in SC-CO₂ through artificial intelligence. Oxaprozin is a nonsteroidal anti-inflammatory drug which is useful in arthritis disease to improve swelling and pain. Oxaprozin is a type of BCS class II (Biopharmaceutical Classification) drug with low solubility and bioavailability. Here in order to optimize and improve the solubility of Oxaprozin, three ensemble decision tree-based models including random forest (RF), Extremely random trees (ET), and gradient boosting (GB) are considered. 32 data vectors are used for this modeling, moreover, temperature and pressure as inputs, and drug solubility as output. Using the MSE metric, ET, RF, and GB illustrated error rates of 6.29E-09, 9.71E-09, and 3.78E-11. Then, using the R-squared metric, they demonstrated results including 0.999, 0.984, and 0.999, respectively. GB is selected as the best fitted model with the optimal values including 33.15 (K) for the temperature, 380.4 (bar) for the pressure and 0.001242 (mole fraction) as optimized value for the solubility.

Synthesis of Trisubstituted Oxazoles via Aryne Induced [2,3] Sigmatropic Rearrangement-Annulation Cascade

A transition-metal-free, [2,3] sigmatropic rearrangement-annulation cascade of 2-substituted thio/amino acetonitriles with arynes allowing the synthesis of 2,4,5-trisubstituted oxazoles under mild conditions has been demonstrated. The key sulfur/nitrogen ylides were generated by the initial S/N arylation followed by proton transfer, which was followed by the selective [2,3] sigmatropic rearrangement involving the -CN moiety and a subsequent annulation to afford the desired products in reasonable yields.

Design, synthesis and biological evaluation of 3-(2-aminooxazol-5-yl)-2H-chromen-2-one derivatives

BACKGROUND

In view of wide range of biological activities of oxazole, a new series of oxazole analogues was synthesized and its chemical structures were confirmed by spectral data (Proton/Carbon-NMR, IR, MS etc.). The synthesized oxazole derivatives were screened for their antimicrobial and antiproliferative activities.

RESULTS AND DISCUSSION

The antimicrobial activity was performed against selected fungal and bacterial strains using tube dilution method. The antiproliferative potential was evaluated against human colorectal carcinoma (HCT116) and oestrogen- positive human breast carcinoma (MCF7) cancer cell lines using Sulforhodamine B assay and, results were compared to standard drugs, 5-fluorouracil and tamoxifen, respectively.

CONCLUSION

The performed antimicrobial activity indicated that compounds 3, 5, 6, 8 and 14 showed promising activity against selected microbial species. Antiproliferative screening found compound 14 to be the most potent compound against HCT116 (IC₅₀ = 71.8 µM), whereas Compound 6 was the most potent against MCF7 (IC₅₀ = 74.1 µM). Further, the molecular docking study has been carried to find out the interaction between active oxazole compounds with CDK8 (HCT116) and ER-α (MCF7) proteins indicated that compound 14 and 6 showed good dock score with better potency within the ATP binding pocket and may be used as a lead for rational drug designing of the anticancer molecule.

Improved Synthesis of Anxiolytic, Anticonvulsant and Antinociceptive α2/α3-GABA(A)ergic Receptor Subtype Selective Ligands as Promising Agents to Treat Anxiety, Epilepsy, as well as Neuropathic Pain

An improved synthesis of the anxiolytic, anticonvulsant and antinociceptive compounds: Hz-166, and its bioisosteres 1,2,4-oxadiazole (MP-III-080) and 1,3-oxazole (KRM-II-81) were executed in higher yields and with more facile purification methods (crystallization, etc.) in multigram quantities without column chromatography. In the synthesis of KRM-II-81, an alternative procedure was employed using the selective reducing reagent, potassium diisobutyl-t-butoxy aluminum hydride (PDBBA), to prepare the desired C(3)-aldehyde in the absence of [N(5)-C(6)] imine reduction in good yield on 20 gram scale.

Continuous multistep synthesis of 2-(azidomethyl)oxazoles

An efficient three-step protocol was developed to produce 2-(azidomethyl)oxazoles from vinyl azides in a continuous-flow process. The general synthetic strategy involves a thermolysis of vinyl azides to generate azirines, which react with bromoacetyl bromide to provide 2-(bromomethyl)oxazoles. The latter compounds are versatile building blocks for nucleophilic displacement reactions as demonstrated by their subsequent treatment with NaN₃ in aqueous medium to give azido oxazoles in good selectivity. Process integration enabled the synthesis of this useful moiety in short overall residence times (7 to 9 min) and in good overall yields.

Catalytic transformation of esters of 1,2-azido alcohols into α-amido ketones

The esters of 1,2-azido alcohols were transformed into α-amido ketones without external oxidants through the Ru-catalyzed formation of N–H imines with the liberation of N₂ followed by intramolecular migration of the acyl moiety.

Clinical pharmacokinetics of oxaprozin

Oxaprozin is a nonsteroidal anti-inflammatory drug which reaches peak plasma concentrations 2 to 6 hours after oral administration. Oxaprozin binds extensively, in a concentration-dependent manner, to plasma albumin. The area under the plasma concentration-time curve (AUC) of oxaprozin is linearly proportional to the dose for oral doses up to 1200 mg. At doses greater than 1200 mg there is an increase in the unbound fraction of drug, leading to an increased clearance and volume of distribution (Vd) of total oxaprozin. Accumulation of the drug at steady state is between 40 and 58% lower than predicted by single dose data. After administration of multiple doses, the apparent oral clearance (CL/F) and Vd of total oxaprozin increased while those of the unbound drug decreased significantly. Substantial concentrations of oxaprozin are attained in synovial fluid, which is a proposed site of action for nonsteroidal anti-inflammatory drugs. Relationships between total plasma, unbound plasma and synovial concentrations, and therapeutic and toxicological effects have yet to be established. Oxaprozin is eliminated following biotransformation to glucuroconjugated metabolites which are excreted in urine and bile, with little drug being eliminated unchanged. Two hydroxylated metabolites have been shown to possess anti-inflammatory activity. Hepatic disease and rheumatoid arthritis do not significantly alter the disposition of oxaprozin. Patients with renal impairment demonstrate an increase in unbound plasma concentrations of oxaprozin. A significant drug interaction has been demonstrated between oxaprozin and aspirin (acetylsalicylic acid).

Drug dosage in the elderly. Is it rational?

Pharmacotherapy in the elderly requires an understanding of the age-dependent changes in function and composition of the body. Aging is characterised by a progressive loss of functional capacities of most if not all organs, a reduction in response to receptor stimulation and homeostatic mechanisms, and a loss of water content and an increase of fat content in the body. The most important pharmacokinetic change in old age is a decrease in the excretory capacity of the kidney; in this regard, the elderly should be considered as renally insufficient patients. The decline in the rate of drug metabolism with advancing age is less marked. In addition, the volume of distribution and the oral bioavailability of drugs may be changed in the elderly compared with younger individuals. Average dosage adjustments for the aged can be derived from simple equations and mean pharmacokinetic parameters from older and younger adults. However, these average dose adjustment factors neglect the large variation in the decline in organ functions among the elderly. Individual dose adjustment factors can be obtained from the drug clearance in a particular patient, where clearance/fractional bioavailability (CL/f) may be calculated from the area under the plasma concentration-time curve (AUC) of the drug in question. Using pharmacokinetic guidelines for dose adjustments, the same plasma drug concentrations result in elderly as in younger adults. However, we are frequently confronted with pharmacodynamic changes in old age which alter the sensitivity to drugs, irrespective of changes in drug disposition. For instance, the sensitivity of the cardiovascular system to beta-adrenergic agonists and antagonists decreases in old age and the incidence of orthostatic episodes in response to drugs that lower blood pressure is increased. The CNS is especially vulnerable in the elderly; agents that affect brain function (anaesthetics, opioids, anticonvulsants, psychotropic drugs) must be used very cautiously in this age group. The increased responsiveness to drugs in the elderly renders the measurement of drug plasma concentrations an attractive method to monitor pharmacotherapy in this age group. Sensitive technology to quantitatively determine plasma drug concentrations is available. However, optimal therapeutic plasma concentrations have not been established for most drugs in the elderly. Investigations concerning drug pharmacokinetic-pharmacodynamic relationships in the aged are an important area of future work in clinical pharmacology.

Oxaprozin and piroxicam, nonsteroidal antiinflammatory drugs with long half-lives: effect of protein-binding differences on steady-state pharmacokinetics

The nonsteroidal antiinflammatory drugs (NSAIDs) oxaprozin and piroxicam have long elimination half-lives (t 1/2 approximately 55 hours), permitting once-daily dose regimens. The protein-binding characteristics of these drugs, however, vary widely. This study examines the effect of these binding differences on the drugs' disposition kinetics at steady state. A total of 52 participants (26 young healthy volunteers, and 26 elderly osteoarthritic patients, 15 men and 37 women (2 of them poor metabolizers of debrisoquine [CYP2D6]) completed the two-period, two-treatment, randomized, single-dose and 21-day, once-daily multiple-dose, cross-over study. Doses of oxaprozin and piroxicam were 1,200 mg once daily and 20 mg once daily, respectively. Mean single-dose kinetic parameters of oxaprozin versus piroxicam did not differ more than +/-14% (t1/2, 53.0 versus 57.4 hours; apparent oral clearance adjusted for 70-kg body weight [Clpo], 0.139 versus 0.121 L/hr; apparent volume of distribution adjusted for 70-kg body weight [Vd/F]; 10.2 L versus 9.13 L). Protein binding was plasma-concentration dependent with oxaprozin (range, 10-400 mg/L) but not with piroxicam (range, 1-30 mg/ L). Steady-state conditions were established within 3 days with oxaprozin but took almost 12 days with piroxicam. Compared with the single-dose values, steady-state Clpo (Clpo,ss) and Vd/F of total drug increased with oxaprozin by almost 127% but remained within +/-10% with piroxicam. Post-steady-state apparent t 1/2 of the total and unbound drugs of approximately 62 hours were similarly prolonged with piroxicam but differed substantially with oxaprozin (50.6 hours [total drug] versus 23.8 hours [unbound drug]). Single dose Clpo (Clpo,sd) values of both NSAIDs were significantly correlated in the study populations. With both NSAIDs, Clpo in the two poor metabolizers of debrisoquine was within +/-20% of mean values for the population. Clinically important age- and gender-dependent decreases were not observed in the weight-adjusted, Clpo,sd or Vd/F values of the total drug for either NSAID. Clearances of the two NSAIDs were significantly correlated, suggesting that a common P450 isozyme (most likely CYP2C9, in that piroxicam is a known substrate of this isozyme) may be at least partly involved in the oxidative metabolism of these NSAIDs.

Toxicity of nonsteroidal anti-inflammatory drugs in the elderly: is advanced age a risk factor?

We reviewed the pharmacokinetic, physiologic and epidemiologic data concerning nonsteroidal anti-inflammatory drug (NSAID)-induced gastropathy and renal insufficiency in the elderly through a structured critical reading of the literature. References were collected through a search of MEDLINE and consultation with experts in the field. While there is an abundance of pharmacokinetic data comparing relevant parameters in young and old subjects, methods are not uniform and findings are inconsistent. Prostaglandin physiology appears to be altered in older versus younger subjects. Most surprisingly, there is a scarcity of epidemiologic data examining the contribution of age as a risk factor for NSAID-induced ulcers and/or renal insufficiency. The data that do exist do not clearly support age as an independent risk factor; and we believe that comorbidities, comedications and past history are more important predictors of NSAID-induced toxicity than age and more relevant in regard to therapeutic decision-making for this patient population.

Inverse nonlinear pharmacokinetics of total and protein unbound drug (oxaprozin): clinical and pharmacokinetic implications

The nonsteroidal antiinflammatory drug oxaprozin is extensively bound to plasma proteins in a concentration-dependent manner. This study demonstrates for the first time the inverse nonlinear pharmacokinetics of total and unbound oxaprozin and presents clinical implications of this phenomenon. A total of 71 healthy volunteers participated in single- and multiple-dose studies. In study I, 0.6-, 1.2-, and 1.8-gm doses of oxaprozin were given on an empty stomach in a randomized, crossover trial (n = 35). In studies II and III, 1.2- and 1.8-gm doses, respectively, were given once a day for 8 days (n = 12 and 24, respectively). Serial blood samples for total and unbound drug assays were taken over a 240-hour period in study I and for a 24-hour period on days 1, 5, and 8 in studies II and III. After administration of 1.2 gm once daily, steady-state conditions were established by day 5. Actual average steady-state plasma concentrations (Cavg) were lower than those predicted from the single-dose study based on linear kinetics for the total drug, but higher for the unbound drug. Nonlinear changes in Vd/F were also noted with multiple-dose administration. Vd/F increased by 47% for total drug but decreased by 61% for unbound drug relative to single-dose values. Half-lives after single-dose administration for total and unbound drug determined from 24 to 240 hours and from 24 to 72 hours, respectively, were dose independent for total drug, but dose dependent for unbound drug. Half-lives after multiple-dose administration measured from 24 to 48 hours in study II decreased further. In conclusion, oxaprozin clearance for the total drug was increased while that of the unbound drug was decreased after repetitive dosing. This inverse pharmacokinetic behavior has been attributed to the two noncompensatory kinetic effects: concentration-dependent protein binding and saturable metabolism of oxaprozin.

Hepatic drug metabolism and aging

Although there is considerable variation in the effect of age on drug biotransformation, the metabolism of many drugs is impaired in the elderly. Age-related physiological changes, such as a reduction in liver mass, hepatic metabolising enzyme activity, liver blood flow and alterations in plasma drug binding may account for the decreased elimination of some metabolised drugs in the elderly. It is difficult, however, to separate an effect of aging from a background of marked variation in the rate of metabolism due to factors such as individual metabolic phenotype, environmental influences, concomitant disease states and drug intake. The prevailing data suggest that initial doses of metabolised drugs should be reduced in older patients and then modified according to the clinical response. In most studies the elderly appear as responsive as young individuals to the effects of compounds which induce or inhibit the activity of cytochrome P450 isozymes. Concurrent use of other agents, which induce or inhibit drug metabolism, mandates dose adjustment as in younger patients. Many questions remain unanswered. For instance, limitations of in vitro studies prevent any firm conclusion about changes in hepatic drug metabolising enzyme activity in the elderly. With aging, some pathways of drug metabolism may be selectively affected, but this has not been adequately scrutinised. The possibility that metabolism of stereoisomers may be altered in the elderly has not been adequately tested. The effect of aging on the distribution of polymorphic drug metabolism phenotypes is still not established, despite potential implications for disease susceptibility and survival advantage.

Pharmacokinetics of oxaprozin in women receiving conjugated estrogen

The kinetics of a single 1200 mg oral dose of oxaprozin, a nonsteroidal antiinflammatory agent of the propionic acid class, was studied in 22 healthy female volunteers aged 21 to 64 years. Eleven subjects had been taking a conjugated estrogen preparation for at least 3 months; the other 11 subjects served as control women who were not taking conjugated estrogens. Mean pharmacokinetic variables in control and conjugated estrogen groups were: volume of distribution, 15.1 vs 14.1 l; elimination half-life, 59.8 vs 54.2 h; clearance, 3.2 vs 3.1 ml/min; peak plasma concentration, 84.8 vs 90.7 micrograms/ml, respectively. None of the differences were significant. However, the time of peak concentration (8.9 vs 4.0 h) was significantly longer in the control group than in the conjugated estrogen group, respectively (p less than 0.05). Oxaprozin clearance, accomplished by a combination of oxidation and conjugation, is unimpaired by coadministration of conjugated estrogens.

Plasma protein binding of drugs in the elderly

Binding to plasma proteins can affect the pharmacokinetics and pharmacodynamics of drugs. Age is one of many factors which can affect plasma protein binding of drugs. Unfortunately, very few generalities can be drawn from the studies of the effect of age on protein binding. Whether age has an effect on protein binding is dependent not only on the drug, but also on the manner in which the study is conducted. Several studies involve patients with various disease states making assessment of the effect of age alone on protein binding difficult. Results of different studies on the same drug do not always agree--in one case finding no change in protein binding with age and in another, a significant increase or decrease in protein binding. Most drugs which exhibit increased binding (decreased free fraction) in elderly subjects are basic and tend to have a greater affinity for alpha 1-acid glycoprotein than for albumin. The list of drugs exhibiting decreased binding (increased free fraction) in the elderly is longer and includes both acidic and basic drugs. The impact of changes in protein binding with age is dependent on the magnitude of the change, on the pharmacokinetic characteristics of the drug and on its therapeutic index. Some changes, although statistically significant, are not likely to be of importance clinically. From the studies reviewed, the free fraction is changed by greater than 50% in the elderly for only a few drugs, e.g. acetazolamide, diflunisal, etomidate, naproxen, salicylate, valproate and zimeldine.

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

Oxaprozin is a newer non-steroidal anti-inflammatory drug advocated for use in painful rheumatic and inflammatory conditions. As is the case with some other newer non-steroidal anti-inflammatory drugs, oxaprozin offers the convenience of once-daily administration. Published data suggest that oxaprozin 1200 mg once daily is comparable in effectiveness with usual dosages of aspirin, ibuprofen, indomethacin, naproxen, piroxicam and sulindac in the treatment of rheumatoid arthritis and osteoarthritis. More controlled clinical trials in adequate numbers of patients are necessary to evaluate its potential in other rheumatic and inflammatory conditions. Oxaprozin produced fewer gastrointestinal side effects than aspirin, and the short term tolerability of oxaprozin was similar to that of other non-steroidal anti-inflammatory drugs. If further definition of its efficacy and tolerability compared with other non-steroidal anti-inflammatory drugs during long term therapy confirms these initially favourable results, then oxaprozin would appear to offer a useful and convenient alternative in the treatment of painful rheumatic and inflammatory conditions.

Drug-drug and drug-disease interactions with nonsteroidal anti-inflammatory drugs

Nonsteroidal anti-inflammatory drugs may cause a number of drug interactions. They can displace other drugs from serum proteins, and some can affect the metabolism or decrease the renal elimination of other drugs. In addition, they can attenuate the pharmacologic effect of other drugs, such as diuretic and antihypertensive agents, without affecting their disposition. Lastly, many disease states and aging can affect the handling of nonsteroidal anti-inflammatory drugs, mandating dose adjustment of some of these agents in certain clinical conditions. Some drugs may require more of these adjustments than others.

Pharmacokinetics of naproxen in elderly patients

The pharmacokinetics of naproxen have been examined in 13 elderly patients (mean age 84.2 years) and in 9 younger patients (mean age 53.9 years) at the end of a 21 day course of therapy with naproxen 500 mg b.d. The mean pre-dose concentration on days 19, 20 and 21 was significantly higher in the elderly patients than in the controls (60.1 vs. 43.3 micrograms X ml-1). The AUC (0-24) was significantly higher in the elderly subjects only when normalized for body weight (9.1 vs. 5.4 micrograms X ml-1 X h kg-1 p less than or equal to 0.02). The AUC was significantly higher in the elderly group compared to the control group also in the normalized form. The apparent clearance of naproxen was reduced in the elderly compared to the control patients (315 vs. 628 ml X h-1). The percentage protein binding of naproxen was the same in both groups (99.8%) but the free concentration of naproxen was significantly higher in the elderly patients than in the control patients (141 vs. 89.8 ng X ml-1). Although there was no excess of side effects in the elderly patients it is suggested that when naproxen is given to elderly patients, therapy should be started at the lower end of the dosage range.

Interaction of oxaprozin with acetaminophen, cimetidine, and ranitidine

Twelve healthy male volunteers participated in a single-dose four-way crossover study to evaluate potential drug interactions with oxaprozin, a nonsteroidal antiinflammatory agent of the propionic class. The four modes of administration were: a. oxaprozin, 1200 mg alone; b. oxaprozin during concurrent acetaminophen, 500 mg 4 times daily; c. oxaprozin with cimetidine, 300 mg 4 times daily; d. oxaprozin with ranitidine, 150 mg every 12 hours. Acetaminophen, cimetidine, or ranitidine were begun 24 hours prior to oxaprozin dosage and continued for the 10-day duration of each trial. No significant differences existed among the four treatment conditions in peak plasma oxaprozin concentration (86 micrograms/ml), volume of distribution (0.23 l/kg), time of peak concentration (3.7 h after dosage), or elimination half-life (54 h). Oxaprozin oral clearance was significantly lower (by 20%) during both the cimetidine and ranitidine trials versus control (0.047 vs 0.047 vs 0.059 ml/min/kg), but clearance during acetaminophen was not significantly different from control. Thus acetaminophen, cimetidine or ranitidine has only a small influence on the pharmacokinetics of a single oral dose of oxaprozin. The reduction in oxaprozin clearance due to cimetidine or ranitidine is statistically significant but small in magnitude.