Small bowel Procardia XL tablet bezoar mimicking cystic pneumatosis intestinalis

Osmotic-controlled release oral tablets: technology and functional insights

In recent years, oral osmotic tablets have sparked a therapeutic paradigm for controlled-release dosage forms due to their intrinsic insensitivity to physiological and physicochemical factors. Despite these benefits, the design of an optimal osmotic technology is precluded by various challenges. These limitations include manufacturing complexity, the lack of understanding of the functional mechanics, and inadequate optimization for the desired bio-performance. This paper systematically reviews the development of an osmotic-driven drug delivery system and the strategy for a zero-order release profile with an emphasis on swellable core technology. We discuss the applicability of the various types of osmotic tablets, their suitability to specific needs, and factors that drive the technology selection. Finally, we review the challenges, opportunities, and future perspectives associated with osmotic tablets.

Clinical and Forensic Aspects of Pharmacobezoars

BACKGROUND

Pharmacobezoars are specific types of bezoars formed when medicines, such as tablets, suspensions, and/or drug delivery systems, aggregate and may cause death by occluding airways with tenacious material or by eluting drugs resulting in toxic or lethal blood concentrations.

OBJECTIVE

This work aims to fully review the state-of-the-art regarding pathophysiology, diagnosis, treatment, and other relevant clinical and forensic features of pharmacobezoars.

RESULTS

Patients of a wide range of ages and of both sexes present with signs and symptoms of intoxications or more commonly gastrointestinal obstructions. The exact mechanisms of pharmacobezoar formation are unknown but are likely multifactorial. The diagnosis and treatment depend on the gastrointestinal segment affected and should be personalized to the medication and the underlying factor. A good and complete history, physical examination, image tests, upper endoscopy, and surgery through laparotomy of the lower tract are useful for diagnosis and treatment.

CONCLUSION

Pharmacobezoars are rarely seen in clinical and forensic practice. They are related to controlled or immediate-release formulations, liquid, or non-digestible substances, in normal or altered digestive motility/anatomy tract, and in overdoses or therapeutic doses, and should be suspected in the presence of risk factors or patients taking drugs which may form pharmacobezoars.

A Comprehensive Map of FDA-Approved Pharmaceutical Products

With the increasing research and development (R&D) difficulty of new molecular entities (NMEs), novel drug delivery systems (DDSs) are attracting widespread attention. This review investigated the current distribution of Food and Drug Administration (FDA)-approved pharmaceutical products and evaluated the technical barrier for the entry of generic drugs and highlighted the success and failure of advanced drug delivery systems. According to the ratio of generic to new drugs and the four-quadrant classification scheme for evaluating the commercialization potential of DDSs, the results showed that the traditional dosage forms (e.g., conventional tablets, capsules and injections) with a lower technology barrier were easier to reproduce, while advanced drug delivery systems (e.g., inhalations and nanomedicines) with highly technical barriers had less competition and greater market potential. Our study provides a comprehensive insight into FDA-approved products and deep analysis of the technical barriers for advanced drug delivery systems. In the future, the R&D of new molecular entities may combine advanced delivery technologies to make drug candidates into more therapeutically effective formulations.

Oral osmotically driven systems: 30 years of development and clinical use

The number of marketed oral osmotically driven systems (OODS) has doubled in the last 10 years. The main clinical benefits of OODS are their ability to improve treatment tolerability and patient compliance. These advantages are mainly driven by the capacity to deliver drugs in a sustained manner, independent of the drug chemical properties, of the patient's physiological factors or concomitant food intake. However, access to these technologies has been restricted by the crowded patent landscape and manufacturing challenges. In this review article, we intend to give an overview of the OODS development in the last 30 years, detailing the technologies, specific products and their clinical use. General guidance on technology selection is described in light of the recent advances in the field. The clinical performance of these technologies is also discussed, with a focus on food effects and the in vivo-in vitro correlation. Special attention is paid to safety given the controversial case study of Osmosin. Overall, oral osmotically driven systems appear to be a promising technology for product life-cycle strategies.

Bezoar Formation Requiring Endoscopic Removal After Intentional Overdose of Extended-Release Nifedipine

A 61-year-old Caucasian woman was transported to the emergency department after intentionally ingesting several different prescription drugs. She had been found by her husband in an unconscious state with empty bottles of extended-release venlafaxine, extended-release nifedipine, sertraline, and atorvastatin. She was intubated in the emergency department and transferred to the intensive care unit. After 36 hours in the intensive care unit, she was stabilized and brought to a general medical ward. She later developed profound recurrent hypotension with systolic blood pressures ranging from 40-70 mm Hg and diastolic blood pressures of 0-40 mm Hg. She was readmitted to the intensive care unit, where a computed tomography scan revealed a mass in her stomach. A gastroenterology consultation was obtained, and an esophagogastroduodenoscopy (EGD) was performed, during which a large drug bezoar was discovered and removed. The drugs were identified as extended-release nifedipine with a few granules of extended-release venlafaxine. Unfortunately, the patient died 3 days after the EGD from multisystem organ failure related to the overdose. Clinicians who encounter drug overdoses should be aware of the possibility of drug bezoar formation and should consider endoscopic removal as a potential treatment option.

Antihypertensive pharmacobezoar

Most antihypertensive drugs have known side effects that are elicited by the careful clinician taking care of hypertensive patients. However, many antihypertensive medications utilize drug delivery systems that prolong the duration of blood pressure reduction. The gastrointestinal therapeutic system that is used with nifedipine, isradipine, and verapamil has a unique side effect. Obstruction may occur at the site of a previous surgical repair (pyloric stenosis or gastroplasty) or stenosis of the esophagus, small intestine, or colon. The same delivery system is used with methylphenidate, oxybutynin, glipizide, and doxazosin. Although this complication is rare, physicians who prescribe and care for hypertensive patients should recognize this potential problem.

Retention of extended release nifedipine capsules in a patient with enteric stricture causing recurrent small bowel obstruction

Medication bezoars from extended release medication have been reported in the literature. This has become an increasing phenomenon with the popularity of extended release formulations, which aim to increase therapeutic compliance. We report on a patient who experienced recurrent bouts of small bowel obstruction, necessitating surgical exploration.

Gastrointestinal safety of an extended-release, nondeformable, oral dosage form (OROS: a retrospective study

BACKGROUND

The OROS osmotic (OSM) dosage form optimises extended-release oral administration by controlling the rate of drug release for a predetermined time, providing constant, patterned, or pulsed delivery profiles. OSM products include prescription medications for urology, CNS, and cardiovascular indications, as well as over-the-counter nasal/sinus congestion medications.

METHODS

This retrospective study examines US gastrointestinal (GI) safety data for the OROS dosage form following nearly two decades of use. Although GI injury and obstruction are known effects of oral medications, some reports have suggested that extended-release products pose a greater risk of GI injury and obstruction than other oral dosage forms. Products incorporating OROS technology are being prescribed to an expanding range of patients; a review of the GI safety data for this dosage form thus seemed timely and appropriate. US safety information was obtained from three sources: English language literature published from 1982 until June 1, 2000 from five major biomedical databases;postmarketing safety reports from January 1, 1983 until June 1, 2000 available through the Freedom of Information Act; andcommercial safety information obtained directly from ALZA Corporation's in-house safety database for those OSM products for which ALZA has reporting responsibility. US distribution data from IMS National Prescription Audit trade mark Plus data were used to estimate cumulative product distribution totals. These totals were combined with numbers of unique GI events to determine the estimated frequency of events.

RESULTS

Nearly 13 billion OSM tablets are estimated to have been distributed in the US. The incidence of all clinically significant GI adverse events for OSM products (including intestinal, gastric, and oesophageal irritation, injury, and obstruction) reported in the US was approximately one case in >76 million tablets distributed. The majority (78%; estimated incidence: one case in 29 million tablets) of cases were reported in patients taking Procardia XL (nifedipine). Oesophageal and lower GI obstruction were reported primarily in patients with pre-existing abnormalities or disease of the GI tract. Among paediatric patients, one obstruction was reported in an estimated 37.7 million tablets distributed. Reports of GI irritation associated with OSM products were consistent with known effects of the same drug substances in other dosage forms.

CONCLUSION

A review of long-term safety experience with products using OSM controlled-release technology yields a low incidence of clinically significant GI events. Properly prescribed, extended-release products provide substantial therapeutic and convenience benefits without additional risk.

Extended-release nifedipine bezoar identified one year after discontinuation

OBJECTIVE

To report a case of tablet impaction of nifedipine extended-release tablets (Procardia XL) discovered one year after discontinuation of the drug in a patient with peptic stricture.

DATA SOURCES

English-language references identified via a MEDLINE search from 1966 through September 1998 and bibliographic review of pertinent articles.

DATA SYNTHESIS

Extended-release nifedipine has been associated with the formation of medication bezoars in case reports. Bezoars are concretions of undigested material within the gastrointestinal (GI) tract. Although they can occur throughout the GI tract, bezoars are most frequently located in the stomach and, rarely, in the duodenum. We report an unusual case of tablet impaction with a gastric outlet obstruction in the duodenal area discovered one year after the patient stopped taking extended-release nifedipine.

CONCLUSIONS

Extended-release nifedipine is associated with tablet impaction, even long after discontinuing administration. Although rare, clinicians should be aware of this potential problem when prescribing extended-release medications to patients at risk, and should consider this possible etiology when refractory epigastric pain and weight loss occur.

Medication bezoars: a literature review and report of a case

OBJECTIVE

To describe a case of a medication bezoar and to review the clinical presentation, diagnosis, risk factors, pathogenesis, complications, and treatment of medication bezoars.

DATA SOURCES AND STUDY SELECTION

A MEDLINE search (January 1966-December 1997) of the English-language literature pertaining to bezoars was performed. These articles were scanned, and literature specifically discussing medication bezoars was selected. Additionally, the reference sections of pertinent review and case reports were scanned for additional relevant literature.

DATA SYNTHESIS

Bezoars are concretions of foreign material within the body. In the case of medication bezoars, these concretions occur within the digestive tract and are composed of medications and/or medication vehicles. Rarely, however, is bezoar formation solely due to a medication. In nearly all reported cases the patient had one or more significant risk factors that contributed to bezoar formation. The exact method by which medications bezoars form is dependent on the particular type or combination of medications involved. Bezoar formation may be associated with significant complications for the patient due to the presence of the bezoar and because of the effects of the medication within the bezoar. Treatment of medication bezoars depends largely on the location and the cause of the bezoar.

CONCLUSIONS

Medication bezoars are a rare but potentially serious complication of medication use in certain patients. These patients often present with signs and symptoms consistent with an obstruction of the gastrointestinal tract and represent an even greater diagnostic challenge due to the rarity of this complication. These patients also face significant complications from both the bezoar and the medication within the bezoar. To date, treatment of medication bezoars involves mainly physical manipulation of the bezoar through lavage, endoscopic removal, or, in most cases, surgical removal.