A review of the gastrointestinal therapeutic system (GITS) formulation and its effectiveness in the delivery of antihypertensive drug treatment (focus on nifedipine GITS)

Effect of Omeprazole Administration on the Pharmacokinetics of Oral Extended-Release Nifedipine in Healthy Subjects

Oral extended-release (ER) dosage forms have been used to sustain blood drug levels, reduce adverse events, and improve patient compliance. We investigated potential effects of comedication on pharmacokinetic exposure of nifedipine ER products with different formulation designs and manufacturing processes. A clinical study compared a generic version of nifedipine ER tablet with pH-dependent dissolution behavior with an osmotic pump product with pH independent drug release under fasting condition. In this study, two nifedipine tablet products were tested with or without short-term omeprazole comedication in healthy subjects. Seven-day administration of omeprazole before nifedipine dosing significantly increased the gastric pH, and subsequently increased the geometric least square (LS) means of area under the concentration-time curve from time zero to the last measurable timepoint (AUC0-t ) and maximum plasma concentration (Cmax ) of nifedipine to 132.6% (90% confidence interval (CI): 120.6-145.7%) and 112.8% (90% CI: 100.8-126.3%) for pH-dependent ER tablets, and 120.6% (90% CI: 109.7-132.5%) and 122.5% (90% CI: 113.7-131.9%) for the pH-independent ER tablets, respectively. Similar extent of increase in AUC0-t and Cmax was confirmed in the subpopulations whose gastric pH was ≥ 4 or ≤ 3 in subjects with or without omeprazole administration. Given that similar increases in drug exposures were observed for both pH-dependent and pH-independent nifedipine formulations and the geometric LS mean ratios were between 112% and 133% with and without short-term omeprazole comedication, the gastric pH may have limited effects on omeprazole-induced nifedipine PK changes on the tested formulations. The inhibition of cytochrome P450 3A4 activity may play a significant role causing nifedipine exposure changes for both formulations, which would warrant additional assessment.

Comparative efficacy of generic nifedipine versus brand-name amlodipine for hypertension management in Taiwan

The control rate of hypertension remains concerning, indicating the requirement for better management strategies. The calcium channel blockers brand‐name amlodipine and nifedipine with extended‐release formulations demonstrate similar clinical efficacy. However, the efficacy of generic nifedipine remains obscure. We compared the efficacy of generic nifedipine and brand‐name amlodipine in terms of cardiovascular (CV) outcomes. Patients prescribed generic nifedipine (SRFC CYH) or brand‐name amlodipine besylate (Norvasc, Pfizer) between August 1, 2017, and July 31, 2018, were enrolled; patients with CV events within 3 months were excluded. CV outcomes included CV death, nonfatal myocardial infarction (MI), nonfatal ischemic stroke, hospitalization for heart failure, and composite endpoints of 3P‐ and 4P‐major adverse cardiac events (MACE). A total of 1625 patients treated with nifedipine (SRFC CYH) and 16 587 patients treated with Norvasc were included. After propensity score matching, there were 995 and 4975 patients in the nifedipine CYH and Norvasc groups, respectively. At a mean follow‐up period of 30.3 ± 6.4 months, nifedipine CYH was comparable to Norvasc in terms of CV death (P = .107), nonfatal MI (P = .121), nonfatal ischemic stroke (P = .453), hospitalization for heart failure (P = .330), 3P‐MACE (P = .584), and 4P‐MACE (P = .274). Cox regression analysis revealed that nifedipine CYH and Norvasc had similar efficacy in terms of 3P‐MACE (hazard ratio, 0.970; 95% confidence interval, 0.601–1.565, P = .900) and 4P‐MACE (hazard ratio, 0.880; 95% confidence interval, 0.628–1.233, P = .459). In conclusion, Nifedipine SRFC CYH and Norvasc have comparable clinical efficacy for hypertension management.

An In Vitro Dissolution Method for Testing Extended-Release Tablets Under Mechanical Compression and Sample Friction

The release and dissolution of an active pharmaceutical ingredient (API) from the solid oral formulation into the gastrointestinal (GI) tract is critical for the drug's absorption into systemic circulation. Extended-release (ER) solid oral dosage forms are normally subjected to physical shear and grinding forces as well as pressure exerted by peristaltic movements when passing through the GI tract. The complex physical contraction and sample friction exerted by the GI tract are not simulated well by compendial dissolution methods. These limitations render traditional in vitro dissolution testing unable to discriminate and predict a product's in vivo performance. The objective of this study was to develop a dissolution method that better simulates the GI environment that products are subject to when taken by patients. A newly designed Mechanical Apparatus under GI Conditions (MAGIC) was assembled with a dissolution platform and mechanical capabilities to allow in vitro dissolution testing under sample contractions and friction. The dissolution platform, with medium flow-through configuration, was manufactured by 3D printing. A 60 mg polymer matrix-based ER nifedipine product was tested. To simulate GI physiological conditions during the dissolution testing, the flow rate of the medium, and a combination of mechanical compression with rotation induced sample friction at various rotation frequencies were explored. The polymer matrix-based nifedipine ER formulation used here failed its controlled release functionality in the simulated GI environment under mechanical compression and sample friction. The results showed that the MAGIC system, with flow-through configuration under compression and sample friction, has advantages over compendial methods in testing ER solid oral formulations.

Nifedipine Release From Extended-Release Solid Oral Formulations Using In Vitro Dissolution Testing Under Simulated Gastrointestinal Compression

Drug release plays a critical role in defining bioavailability for an extended release solid oral drug products and predictive dissolution tests are desired to establish clinically relevant quality standards for batch release. The objective of this study focuses on exploring the possible impacts of 1 gastrointestinal (GI) parameter for 1 drug: simulated GI contractions on nifedipine release (in 2 extended release solid oral formulations). The 60 mg nifedipine osmotic pump product A, and polymer matrix-based products B and C were examined in the study. An in-house dissolution system was used to simulate various levels of GI contractions on tested samples, and to monitor changes of sample mechanical properties during dissolution testing. The results show that the polymer matrix-based formulation failed to provide controlled release when simulated GI contraction was above 100 g of force. The method may be useful for polymer matrix-based products to assess potential formulation-related interactions with the GI tract during in vivo drug dissolution.

Effects of Dissolution Medium pH and Simulated Gastrointestinal Contraction on Drug Release From Nifedipine Extended-Release Tablets

In contrast to nifedipine matrix-based extended-release dosage forms, the osmotic pump drug delivery systems have a zero-order drug release independent of external variables such as pH, agitation rate, and dissolution media. The objective of this study focuses on the in vitro evaluation of the mechanical properties of osmotic pump and polymer matrix-based formulations in dissolution media, and the potential impacts that media pH and simulated gastrointestinal contraction have on drug release. Two strengths of osmotic pump product A and polymer matrix-based product B were used in this study. An in-house system was developed with the capability of applying mechanical compression and monitoring mechanical properties of sample during dissolution testing. A United States Pharmacopeia or an in-house apparatus was used for dissolution testing under various conditions. Compared to the product A, the mechanical properties of the product B change significantly at various pHs and mechanical compressions. The results suggest that polymer matrix-based products bear a risk of formulation-related interactions with the gastrointestinal tract during in vivo drug dissolution, especially in the case of concomitant pH and gastric contractile changes. Modified dissolution testing devices may help formulation scientists in product development and provide regulatory agencies with an additional metric for quality assurance of drug products.

Robustness of barrier membrane coated metoprolol tartrate matrix tablets: Drug release evaluation under physiologically relevant in vitro conditions

Robust in vitro drug release behavior is an important feature of extended release (ER) hydrophilic matrix formulations for accurate prediction of in vivo drug release. In this study, ER hydrophilic matrix tablets of metoprolol tartrate were formulated using a high viscosity grade of hypromellose as a rate-limiting polymer. Expectedly, this formulation showed an undesirable initial burst release followed by controlled drug release. Application of a barrier membrane (BM) coating of ethylcellulose with a pore former (hypromellose) resulted in the elimination of the burst effect. The aim of this study was to investigate the robustness of in vitro metoprolol release from BM-coated hydrophilic matrix tablets by simulating the physicochemical properties of gastrointestinal fluids and mechanical stress in the fasted- and fed state human gastrointestinal (GI) tract. Uncoated and BM-coated matrices were subjected to various dissolution studies simulating the varying pH conditions and additional physicochemical parameters, and the mechanical stress that can be caused by GI motility during both fasted and fed state GI passage. The BM-coated formulation showed robust drug release without an initial burst in all test scenarios. BM-coated matrix formulations thus represent a very promising approach for obtaining a highly controlled and robust drug release from oral ER formulations.

Undigested Pills in Stool Mimicking Parasitic Infection

Background. Orally ingested medications now come in both immediate release and controlled release preparations. Controlled release preparations were developed by pharmaceutical companies to improve compliance and decrease frequency of pill ingestion. Case Report. A 67-year-old obese male patient presented to our clinic with focal abdominal pain that had been present 3 inches below umbilicus for the last three years. This pain was not associated with any trauma or recent heavy lifting. Upon presentation, the patient reported that for the last two months he started to notice pearly oval structures in his stool accompanying his chronic abdominal pain. This had coincided with initiation of his nifedipine pills for his hypertension. He reported seeing these undigested pills daily in his stool. Conclusion. The undigested pills may pose a cause of concern for both patients and physicians alike, as demonstrated in this case report, because they can mimic a parasitic infection. This can result in unnecessary extensive work-up. It is important to review the medication list for extended release formulations and note that the outer shell can be excreted whole in the stool.

Fixed-dose combination of nifedipine gastrointestinal therapeutic system and candesartan cilexetil in patients with moderate-to-severe essential hypertension: an open-label, long-term safety and efficacy study

WHAT IS KNOWN AND OBJECTIVE

The nifedipine gastrointestinal therapeutic system (GITS)/candesartan cilexetil (N/C) combination was demonstrated to be an effective, well-tolerated antihypertensive therapy in a short-term study. The current study investigated the long-term safety and efficacy of a fixed-dose combination (FDC) of N/C therapy in moderate-to-severe essential hypertension.

METHODS

A multinational, 70-centre, open-label study of N/C treatment for 28 or 52 weeks at a target dose of N60 mg/C32 mg. The primary assessment included the incidence of treatment-emergent adverse events (TEAEs). Efficacy assessments included change from baseline in systolic and diastolic blood pressure (BP).

RESULTS AND DISCUSSION

A total of 508 patients were enrolled, with 417 (82·1%) completing week 28 of treatment. Of these, 200 patients continued treatment, as planned, to week 52, with 193 (96·5%) completing this period. At least one TEAE or drug-related TEAE were reported in 76·8% and 45·3% patients up to week 28, and in 80·7% and 46·9% up to week 52/end of study. Most TEAEs and drug-related TEAEs to week 52 (93·9% and 95·4%, respectively) were mild or moderate in intensity. Rates of drug-related serious AEs were low (0·6%). TEAE-related discontinuations occurred in 10% patients before week 28 and in no additional patients thereafter. N/C provided substantial, sustained reductions in mean systolic and diastolic BP from baseline: 30·1 ± 18·4 and 12·8 ± 10·7 mmHg, respectively, at week 52.

WHAT IS NEW AND CONCLUSIONS

Nifedipine GITS/candesartan cilexetil FDC at the target dose of 60 mg/32 mg was well tolerated for a study duration up to 52 weeks and provided sustained reductions in systolic and diastolic BP.

Diagnosis and Management of Systemic Sclerosis: A Practical Approach

Systemic sclerosis is a devastating multisystem rheumatologic condition that is characterized by autoimmunity, tissue fibrosis, obliterative vasculopathy and inflammation. Clinical presentation and course of the condition vary greatly, which complicates both diagnosis and corresponding treatment. In this regard, recent advances in disease understanding, both clinically and biochemically, have led to newer classification criteria for systemic sclerosis that are more inclusive than ever before. Still, significant disease modifying therapies do not yet exist for most patients. Therefore, organ-based management strategies are employed and research has been directed within this paradigm focusing on either the most debilitating symptoms, such as Raynaud's phenomenon, digital ulcers and cutaneous sclerosis, or life-threatening organ involvement such as interstitial lung disease and pulmonary arterial hypertension. The current trends in systemic sclerosis diagnosis, evidence-based treatment recommendations and potential future directions in systemic sclerosis treatment are discussed.

Nifedipine GITS/Candesartan Combination Therapy Lowers Blood Pressure Across Different Baseline Systolic and Diastolic Blood Pressure Categories: DISTINCT Study Subanalyses

DISTINCT was an 8‐week, double‐blind, randomized study to investigate the antihypertensive efficacy and safety of various nifedipine gastrointestinal treatment system (GITS)/candesartan cilexetil (N/C) dose combinations, vs respective monotherapies or placebo, in patients with diastolic blood pressure (DBP) ≥95 to <110 mm Hg. The current prespecified analysis compared BP reduction in participants with mild vs moderate baseline hypertension (ie, systolic [S]BP <160 mm Hg vs ≥160 mm Hg and DBP <100 mm Hg vs ≥100 mm Hg). A total of 1362 patients were analyzed by descriptive statistics. In all patient subgroups investigated, the NC combinations (ie, N: 20, 30, or 60 mg; C: 4, 8, 16, or 32 mg daily) provided greater SBP and DBP lowering and higher rates of BP control (defined as BP <140/90 mm Hg) than respective monotherapies or placebo, with greatest absolute BP reductions observed in the moderately elevated SBP or DBP subgroups. A trend to dose‐response relationship was observed in each subgroup. In each SBP and DBP subgroup, treatment‐related vasodilatory events (flushing, headache, or edema) were less frequent for patients receiving NC combination therapy than N monotherapy. These analyses support the use of calcium antagonist and angiotensin receptor blocker combination therapy in patients with both mild and moderate hypertension, for whom effective BP normalization and good drug tolerance would greatly reduce the risk of cardiovascular events.