Model-Informed Approaches for Alternative Aripiprazole Dosing Regimens and Missed Dose Management: Towards Better Adherence to Antipsychotic Pharmacotherapy

Pooled Analysis of Gastric Emptying in Patients With Obesity: Implications for Oral Absorption Projection

PURPOSE

Gastric emptying time is one of limiting factors that determines the pharmacokinetic properties of drugs administered by mouth. Despite the high prevalence of obesity worldwide, modifications in gastric emptying time have not been systematically addressed in this set of patients. The current analysis aims to quantitatively address obesity-related changes in gastric emptying time of solids, semisolids, and liquids compared with lean individuals, highlighting the relevant pharmacokinetic implications of oral drug absorption in patients with obesity.

METHODS

We searched the Cochrane Library, PubMed, Web of Science, and Embase for all relevant articles published until November 1, 2020. Differences in gastrointestinal variables in relation to gastric emptying between obese and lean individuals were quantified by weighted mean difference (WMD) and ratio of means (RoM). Robustness of the analyses was evaluated by subgroup analysis and publication bias test.

FINDINGS

A total of 17 studies with 906 participants were included. The gastric half-emptying time of solids (WMD, -10.4 minutes; P = 0.001; RoM, 0.90; P = 0.01) and liquids (WMD, -6.14 minutes; P < 0.001; RoM, 0.83, P = 0.03) was significantly shorter in individuals with obesity compared with lean individuals. These findings were confirmed by the subgroup analyses and publication bias tests.

IMPLICATIONS

Our pooled analysis systemically quantifies the differences in gastric half-emptying time between individuals with obesity and lean individuals, facilitating better understanding and prediction of drug absorption in individuals with obesity through physiologically based pharmacokinetic approaches. Obesity is associated with a faster transit of both solids and liquids through the stomach.

How to handle the delayed or missed dose of rivaroxaban in patients with non-valvular atrial fibrillation: model-informed remedial dosing

BACKGROUND

Rivaroxaban is an oral anticoagulant widely used for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). During long-term anticoagulant therapy, delayed or missed doses are common. This study aimed to explore appropriate remedial dosing regimens for non-adherent rivaroxaban-treated patients.

METHODS

Monte Carlo simulation based on a previously established rivaroxaban population pharmacokinetic/pharmacodynamic (PK/PD) model for patients with NVAF was employed to design remedial dosing regimens. The proposed regimens were compared with remedial strategies in the European Heart Rhythm Association (EHRA) guide by assessing deviation time in terms of drug concentration, factor Xa activity, and prothrombin time.

RESULTS

The proposed remedial dosing regimens were dependent on delay duration. The missed dose should be taken immediately when the delay does not exceed 6 h; a half dose is advisable when the delay is between 6 and 20 h. A missed dose should be skipped if less than 4 h remains before the next dose. The proposed regimens resulted in shorter deviation time than that of the EHRA guide.

CONCLUSION

PK/PD modeling and simulation provide valid evidence on the remedial dosing regimen of rivaroxaban, which could help to minimize the risk of bleeding and thromboembolism.

What should patients do if they miss a dose? A systematic review of patient information leaflets and summaries of product characteristics

Purpose

Medicines regulatory authorities advise that patient information leaflets (PILs) should provide specific advice on what actions to take if one or more doses are missed. We aimed to assess the content in this regard, of PILs and Summaries of Product Characteristics (SmPCs) of prescription only medicines (POMs) marketed in the UK.

Methods

PILs and SmPCs were accessed via the electronic Medicines Compendium. The following terms were used in the advanced search facility: miss(ed), omit(ted), adhere(d), delay(ed), forgot, forget, lapse. Identified documents were screened for instructions on missed doses which were categorised according to level of specificity, and cross-referenced to the National Patient Safety Agency (NPSA) grading of risk of harm from omitted and delayed medicines. Any supporting clinical or pharmacological evidence was identified from SmPCs.

Results

Two thousand two hundred eighty-four documents were identified from 7248 PILs and SmPCs relating to 1501 POMs. Seven hundred eighty-three (52%) POMs had SmPCs or PILs with no instructions on missed doses; 487 POMs (32%) included non-specific advice (e.g. “take as soon as possible”); 138 (9%) provided specific instructions; and 93 (6%) referred patients to seek medical advice. SmPCs for only 13/138 (9%) of those which included specific instructions provided any supporting clinical or pharmacological evidence. Instructions were absent for several medicines where the NPSA assessed that dose omissions may result in significant risk of harm.

Conclusions

Advice on missed doses is generally inadequate. Pharmaceutical companies and regulatory authorities should produce clear and concise instructions on what patients should do if they miss doses, with supporting evidence where necessary.