Effects of food on pharmacokinetics of immediate release oral formulations of aspirin, dipyrone, paracetamol and NSAIDs - a systematic review

Aims

It is common to advise that analgesics, and especially non-steroidal anti-inflammatory drugs (NSAIDs), be taken with food to reduce unwanted gastrointestinal adverse effects. The efficacy of single dose analgesics depends on producing high, early, plasma concentrations; food may interfere with this. This review sought evidence from single dose pharmacokinetic studies on the extent and timing of peak plasma concentrations of analgesic drugs in the fed and fasting states.

Methods

A systematic review of comparisons of oral analgesics in fed and fasting states published to October 2014 reporting kinetic parameters of bioavailability, time to maximum plasma concentration (t_max), and its extent (C_max) was conducted. Delayed-release formulations were not included.

Results

Bioavailability was not different between fasted and fed states. Food typically delayed absorption for all drugs where the fasting t_max was less than 4 h. For the common analgesics (aspirin, diclofenac, ibuprofen, paracetamol) fed t_max was 1.30 to 2.80 times longer than fasted t_max. C_max was typically reduced, with greater reduction seen with more rapid absorption (fed C_max only 44–85% of the fasted C_max for aspirin, diclofenac, ibuprofen and paracetamol).

Conclusion

There is evidence that high, early plasma concentrations produces better early pain relief, better overall pain relief, longer lasting pain relief and lower rates of remedication. Taking analgesics with food may make them less effective, resulting in greater population exposure. It may be time to rethink research priorities and advice to professionals, patients and the public.

Faster, higher, stronger? Evidence for formulation and efficacy for ibuprofen in acute pain

A Cochrane review of ibuprofen in acute pain suggested that rapidly absorbed formulations of salts, or features to speed absorption, provided better analgesia than standard ibuprofen as the free acid. We examined several lines of evidence to investigate what benefit derived from fast-acting formulations. A systematic review of the kinetics of oral ibuprofen (30 studies, 1015 subjects) showed that median maximum plasma concentrations of fast-acting formulations occurred before 50 min (29-35 min for arginine, lysine, and sodium salts) compared with 90 min for standard formulations. An updated analysis of clinical trials (over 10,000 patients) showed that fast-acting formulations produced significantly better analgesia over 6h and fewer remedications than standard formulations in both indirect and direct comparisons. In dental studies, 200-mg fast-acting ibuprofen (number needed to treat 2.1; 95% confidence interval 1.9-2.4) was as effective as 400 mg standard ibuprofen (number needed to treat 2.4; 95% confidence interval 2.2-2.5), with faster onset of analgesia. Individual patient data analysis in dental pain demonstrated a strong correlation between more rapid reduction of pain intensity over 0-60 min and better pain relief over 0-6h. Rapid initial reduction of pain intensity was also linked with reduced need for remedication. Fast-acting formulations of ibuprofen demonstrated more rapid absorption, faster initial pain reduction, good overall analgesia in more patients at the same dose, and probably longer-lasting analgesia, but with no higher rate of patients reporting adverse events. Achieving a better analgesic effect with fast-acting nonsteroidal anti-inflammatory drug formulations has important implications for safety. Formulation chemistry is of potential importance for analgesics.

Enantiospecific ketoprofen concentrations in plasma after oral and intramuscular administration in growing pigs

Background

Ketoprofen is a non-steroidal anti-inflammatory drug which has been widely used for domestic animals. Orally administered racemic ketoprofen has been reported to be absorbed well in pigs, and bioavailability was almost complete. The objectives of this study were to analyze R- and S-ketoprofen concentrations in plasma after oral (PO) and intra muscular (IM) routes of administration, and to assess the relative bioavailability of racemic ketoprofen for both enantiomers between those routes of administration in growing pigs.

Methods

Eleven pigs received racemic ketoprofen at dose rates of 4 mg/kg PO and 3 mg/kg IM in a randomized, crossover design with a 6-day washout period. Enantiomers were separated on a chiral column and their concentrations were determined by liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated and relative bioavailability (F_rel) was determined for S and R –ketoprofen.

Results

S-ketoprofen was the predominant enantiomer in pig plasma after administration of the racemic mixture via both routes. The mean (± SD) maximum S-ketoprofen concentration in plasma (7.42 mg/L ± 2.35 in PO and 7.32 mg/L ± 0.75 in IM) was more than twice as high as that of R-ketoprofen (2.55 mg/L ± 0.99 in PO and 3.23 mg/L ± 0.70 in IM), and the terminal half-life was three times longer for S-ketoprofen (3.40 h ± 0.91 in PO and 2.89 h ± 0.85 in IM) than R-ketoprofen (1.1 h ± 0.90 in PO and 0.75 h ± 0.48 in IM). The mean (± SD) relative bioavailability (PO compared to IM) was 83 ± 20% and 63 ± 23% for S-ketoprofen and R-ketoprofen, respectively.

Conclusions

Although some minor differences were detected in the ketoprofen enantiomer concentrations in plasma after PO and IM administration, they are probably not relevant in clinical use. Thus, the pharmacological effects of racemic ketoprofen should be comparable after intramuscular and oral routes of administration in growing pigs.

Clinically significant drug interactions with antacids: an update

One may consider that drug-drug interactions (DDIs) associated with antacids is an obsolete topic because they are prescribed less frequently by medical professionals due to the advent of drugs that more effectively suppress gastric acidity (i.e. histamine H(2)-receptor antagonists [H2RAs] and proton pump inhibitors [PPIs]). Nevertheless, the use of antacids by ambulant patients may be ever increasing, because they are freely available as over-the-counter (OTC) drugs. Antacids consisting of weak basic substances coupled with polyvalent cations may alter the rate and/or the extent of absorption of concomitantly administered drugs via different mechanisms. Polyvalent cations in antacid formulations may form insoluble chelate complexes with drugs and substantially reduce their bioavailability. Clinical studies demonstrated that two classes of antibacterials (tetracyclines and fluoroquinolones) are susceptible to clinically relevant DDIs with antacids through this mechanism. Countermeasures against this type of DDI include spacing out the dosing interval - taking antacid either 4 hours before or 2 hours after administration of these antibacterials. Bisphosphonates may be susceptible to DDIs with antacids by the same mechanism, as described in the prescription information of most bisphosphonates, but no quantitative data about the DDIs are available. For drugs with solubility critically dependent on pH, neutralization of gastric fluid by antacids may alter the dissolution of these drugs and the rate and/or extent of their absorption. However, the magnitude of DDIs elicited by antacids through this mechanism is less than that produced by H2RAs or PPIs; therefore, the clinical relevance of such DDIs is often obscure. Magnesium ions contained in some antacid formulas may increase gastric emptying, thereby accelerating the rate of absorption of some drugs. However, the clinical relevance of this is unclear in most cases because the difference in plasma drug concentration observed after dosing shortly disappears. Recent reports have indicated that some of the molecular-targeting agents such as the tyrosine kinase inhibitors dasatinib and imatinib, and the thrombopoietin receptor agonist eltrombopag may be susceptible to DDIs with antacids. Finally, the recent trend of developing OTC drugs as combination formulations of an antacid and an H2RA is a concern because these drugs will increase the risk of DDIs by dual mechanisms, i.e. a gastric pH-dependent mechanism by H2RAs and a cation-mediated chelation mechanism by antacids.

Analgesic properties of dexketoprofen trometamol

SUMMARY Dexketoprofen trometamol is the dextrorotary enantiomer of the NSAID ketoprofen formulated as a tromethamine salt. The purpose of administering 50% of the racemic mixture is to keep the same analgesic and anti-inflammatory effect while reducing the adverse events due to both enantiomers. This article describes the pharmacological properties and evaluates the analgesic effects of dexketoprofen trometamol reported in acute and chronic pain conditions. The main conclusions are that dexketoprofen trometamol appears as effective as the double dose of the racemic drug. However, the reduction of adverse effects still has to be demonstrated. In addition, the formulation as tromethamine salt appears beneficial regarding fast onset of analgesia in acute pain conditions.

Evaluation of bioequivalence after oral, intramuscular, and intravenous administration of racemic ketoprofen in pigs

OBJECTIVE

To assess bioequivalence after oral, IM, and IV administration of racemic ketoprofen in pigs and to investigate the bioavailability after oral and IM administration.

ANIMALS

8 crossbred pigs.

PROCEDURES

Each pig received 4 treatments in a randomized crossover design, with a 6-day washout period. Ketoprofen was administered at 3 and 6 mg/kg, PO; 3 mg/kg, IM; and 3 mg/kg, IV. Plasma ketoprofen concentrations were measured by use of high-performance liquid chromatography for up to 48 hours. To assess bioequivalence, a 90% confidence interval was calculated for the area under the time-concentration curve (AUC) and maximum plasma concentration (C(max)).

RESULTS

Equivalence was not detected in the AUCs among the various routes of administration nor in C(max) between oral and IM administration of 3 mg/kg. The bioavailability of ketoprofen was almost complete after each oral or IM administration. Mean +/- SD C(max) was 5.09 +/- 1.41 microg/mL and 7.62 +/- 1.22 microg/mL after oral and IM doses of 3 mg/kg, respectively. Mean elimination half-life varied from 3.52 +/- 0.90 hours after oral administration of 3 mg/kg to 2.66 +/- 0.50 hours after IV administration. Time to peak C(max) after administration of all treatments was approximately 1 hour. Increases in AUC and C(max) were proportional when the orally administered dose was increased from 3 to 6 mg/kg.

CONCLUSIONS AND CLINICAL RELEVANCE

Orally administered ketoprofen was absorbed well in pigs, although bioequivalence with IM administration of ketoprofen was not detected. Orally administered ketoprofen may have potential for use in treating pigs.