The release and absorption profile of an oral medication is influenced by the physicochemical properties of the drug and its formulation, as well as by the anatomy and physiology of the gastrointestinal (GI) tract. During drug development the bioavailability of a new drug is typically assessed in early clinical studies in a healthy adult population. However, many disease conditions are associated with an alteration of the anatomy and/or physiology of the GI tract. The same holds true for some subpopulations, such as paediatric or elderly patients, or populations with different ethnicity. The variation in GI tract conditions compared to healthy adults can directly affect the kinetics of drug absorption, and thus, safety and efficacy of an oral medication. This review provides an overview of GI tract properties in special populations compared to healthy adults and discusses how drug absorption is affected by these conditions. Particular focus is directed towards non-disease dependent conditions (age, sex, ethnicity, genetic factors, obesity, pregnancy), GI diseases (ulcerative colitis and Crohn's disease, celiac disease, cancer in the GI tract, Roux-en-Y gastric bypass, lactose intolerance, Helicobacter pylori infection, and infectious diseases of the GI tract), as well as systemic diseases that change the GI tract conditions (cystic fibrosis, diabetes, Parkinson's disease, HIV enteropathy, and critical illness). The current knowledge about GI conditions in special populations and their impact on drug absorption is still limited. Further research is required to improve confidence in pharmacokinetic predictions and dosing recommendations in the targeted patient population, and thus to ensure safe and effective drug therapies.

Background: Drug-induced orthostatic hypotension (OH) is common, and its resulting cerebral hypoperfusion is linked to adverse outcomes including falls, strokes, cognitive impairment, and increased mortality. The extent to which specific medications are associated with OH remains unclear. Methods and findings: We conducted a systematic review and meta-analysis to evaluate the extent to which specific drug groups are associated with OH. EMBASE, MEDLINE, and Web of Science databases were searched from inception through 23 November 2020. Placebo-controlled randomised controlled trials (RCTs) on any drug reporting on OH as an adverse effect in adults (≥18 years) were eligible. Three authors extracted data on the drug, OH, dose, participant characteristics, and study setting. The revised Cochrane risk-of-bias tool for randomised trials (RoB 2) was used to appraise evidence. Summary odds ratios (ORs) were estimated for OH using fixed effects Mantel–Haenszel statistics. We conducted subgroup analysis on validity of OH measurement, drug dose, risk of bias, age, and comorbidity. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool was used to summarise the certainty of evidence. Of 36,940 citations, 69 eligible RCTs were included in the meta-analysis comprising 27,079 participants. Compared with placebo, beta-blockers and tricyclic antidepressants were associated with increased odds of OH (OR 7.76 [95% CI 2.51, 24.03]; OR 6.30 [95% CI 2.86, 13.91]). Alpha-blockers, antipsychotics, and SGLT-2 inhibitors were associated with up to 2-fold increased odds of OH, compared to placebo. There was no statistically significant difference in odds of OH with vasodilators (CCBs, ACE inhibitors/ARBs, SSRIs), compared to placebo. Limitations of this study are as follows: data limited to placebo-controlled studies, (excluding head-to-head trials), many RCTs excluded older participants; therefore results may be amplified in older patients in the clinical setting. The study protocol is publicly available on PROSPERO (CRD42020168697). Conclusions: Medications prescribed for common conditions (including depression, diabetes, and lower urinary tract symptoms) were associated with significantly increased odds of OH. Drugs causing sympathetic inhibition were associated with significantly increased odds of OH, while most vasodilators were associated with small nonsignificant differences in odds of OH, compared to placebo. Drugs targeting multiple parts of the orthostatic blood pressure (BP) reflex pathway (e.g. sympathetic inhibition, vasodilation, cardio-inhibitory effects) may carry cumulative risk, suggesting that individuals with polypharmacy could benefit from postural BP monitoring.

Orodispersible films (ODFs) possess potential to facilitate oral drug delivery to children; however, documentation of their acceptability in this age group is lacking. This study is the first to explore the initial perceptions, acceptability and ease of use of ODFs for infants and preschool children, and their caregivers through observed administration of the type of dosage form. Placebo ODFs were administered to children stratified into aged 6 to 12 months, 1 year, 2 years, 3 years, 4 years and 5 years old and into those with an acute illness or long-term stable condition in hospital setting. Acceptability of the dosage form and end-user views were assessed by (a) direct observation of administration, (b) questionnaires to caregivers and nurses, and (c) age-adapted questionnaires for children aged 3 years and over. The majority of children (78%) aged 3 years and over gave the ODF a positive rating both on verbal and non-verbal scales. Despite little prior experience, 78% of caregivers expressed positive opinion about ODFs before administration. After the ODFs were taken, 79% of infant caregivers and 86% caregivers of preschool children positively rated their child's acceptance of the ODF. The intraclass correlation coefficient value was 0.92 showing good agreement between ratings of caregivers and nurses. ODFs showed a high degree of acceptability among young children and their caregivers. If drug loading permits, pharmaceutical companies should consider developing pediatric medicines in this format. The methodology described here is useful in assessing the acceptability of active ODF preparations and other dosage forms to children.