Generic Versions of Narrow Therapeutic Index Drugs: A National Survey of Pharmacists' Substitution Beliefs and Practices

Generic Substitutions and Therapeutic Interchanges in Hospital Pharmacies: A Qualitative Study from Western Saudi Arabia

Background: The aim of the present study was to understand hospital pharmacists' views and practices regarding generic substitution and therapeutic interchange. Method: This was a qualitative study involving pharmacists from three Western Saudi governorates: Taif, Makkah, and Jeddah. It included respondents from the Ministry of Health (MoH), military and private hospitals. Pharmacists were selected using a convenient sampling technique and data were collected using a structured face-to-face interview. Results: Fifty-seven pharmacists agreed to participate in this study. In MoH and private hospitals, generic substitution is a pharmacist-initiated act, while therapeutic interchange requires physician approval. Medication unavailability, side effects, patient characteristics, outcomes, and economic status justified most substitution decisions. In military hospitals, both types of substitutions are controlled by an auto-switch policy and physicians should be informed. In all hospitals, there are policies regulating substitution. Medications eligible for interchange mentioned by pharmacists from different hospitals were comparable to some extent. Pharmacists from the private sector considered substitution a supportive economic measure for both hospitals and patients. Most pharmacists highlighted that patient convenience and physician approval are the most challenging situations in substitution practice. Conclusions: An enhanced understanding of substitution and knowledge about medications included in the hospital formulary will be valuable support to the implementation of substitution practice which responds to the patients' needs to improve their outcomes.

Evaluation of a Proposed Approach for the Determination of the Bioequivalence Acceptance Range for Narrow Therapeutic Index Drugs in the European Union

Bioequivalence (BE) of products containing narrow therapeutic index (NTI) drugs in the European Union is currently established by demonstrating that the 90% confidence interval for the ratio of the population geometric means of the test compared to the reference product’s AUC, and in certain cases Cmax, is included within the tighter acceptance range of 90.00−111.11%. An alternative criterion, consisting of narrowed limits based on the within-subject variability of the reference product, was recently proposed. Its performance for a three-period partial replicate design was tested by simulation in terms of power to show BE, type I error (T1E) and sample size requirements. A new condition, a constraint on the test-to-reference geometric mean ratio (cGMR) to be contained within the range of 90.00−111.11%, was also tested. The probability of showing BE when the products differ more than 10% was increased, but only if the reference product’s within-subject variability was moderate-to-high. The inclusion of the additional cGMR limited this. An increase in the T1E (<7%) was observed. The inclusion of the additional cGMR did not change the highest inflation of the T1E. Finally, a significant sample size reduction was observed and the inclusion of the cGMR usually did not increase the required sample size.

State Laws and Generic Substitution in the Year After New Generic Competition

OBJECTIVES

Substitution of brand-name drugs with less expensive, equally effective interchangeable generics is an important strategy for promoting adherence and controlling prescription drug spending. US state laws govern generic substitution, but there is variability among states in how these laws are designed. We aimed to determine how different features of state laws regulating generic substitution are associated with use of generic drugs.

METHODS

Using national claims databases, we studied individuals with commercial insurance or Medicare Advantage plans who newly initiated one of 34 prescription drugs during the year after new generic competition (2017-2018) to determine any association between generic use and 3 different features of state laws. We used multivariable logistic regression to adjust for demographic and clinical characteristics.

RESULTS

Of 502 763 individuals who initiated one of the drugs, 409 856 (81.6%) received a generic version. Those in states requiring patient consent or notification had lower use of generics (81.1% vs 82.9%; adjusted odds ratio 0.89; 95% confidence interval 0.87-0.91; P &lt; .001). By contrast, mandating versus permitting generic substitution and protecting pharmacists from liability did not appear to have significant effects.

CONCLUSIONS

In this study of commercially insured and Medicare Advantage patients, patients in states requiring consent or notification for pharmacists to substitute Food and Drug Administration-certified interchangeable generics had lower use of generics. Laws in 39 states plus the District of Columbia could be amended to improve use of inexpensive and equally effective generic drugs.

Utilization of Generic Cardiovascular Drugs in Medicare's Part D Program

BACKGROUND

Generic medications cost less than brand-name medications and are similarly effective, but brand-name medications are still prescribed. We evaluated patterns in generic cardiovascular medication fills and estimated the potential cost savings with increased substitution of generic for brand-name medications.

METHODS

This was a cross-sectional study of cardiovascular therapies using the Medicare Part D database of prescription medications in 2017. We evaluated drug fill patterns for therapies with available brand-name and generic options. We determined the generic substitution ratio and estimated the potential savings with increased generic substitution at the national, state, and clinician level. We compared states with laws related to mandatory pharmacist generic substitution and patient consent for substitution.

RESULTS

Of ≈$22.9 billion spent on cardiovascular drugs in Medicare Part D prescription programs in 2017, ≈$11.0 billion was spent on medications with both brand-name and generic options. Although only 2.4% of medication fills were for the brand-name choice, they made up 21.2% of total spending. Accounting for estimated brand-name rebates, generic substitution for these medications would save $641 million, including $135 million in costs shouldered by patients. Furthermore, the minority of clinicians with the lowest generic utilization was responsible for a large proportion of the potential cost savings.

CONCLUSIONS

There are substantial potential cost savings from substituting brand-name medications with generic medications. These savings would be primarily driven by lower use of brand-name therapies by the minority of clinicians who prescribe them at increased rates.

Knowledge, perceptions and practices of pharmacists regarding generic substitution in China: a cross-sectional study

OBJECTIVE

To evaluate pharmacists' knowledge, perceptions and practices towards generic substitution in the 11 pilot locations in China.

DESIGN

An online cross-sectional survey using questionnaires was conducted. A convenience sampling technique was implemented to recruit pharmacists.

SETTING AND PARTICIPANTS

The study took place in medical institutions of 11 pilot locations that participated in the pilot national centralised procurement programme in 2019. Two thousand two hundred and ninety-one pharmacists including hospital pharmacists or community pharmacists based on health-systems or clinics participated in the study.

RESULTS

Most of the participants had the good knowledge of requirements for evaluating the quality and efficacy of generic drugs (n=2118; 92.4%), and the definition of generic drugs (n=2078; 90.7%). In terms of perceptions, 67.3% of respondents were of the opinion that generic drugs are equally as effective as the brand-name drugs, and 69.0% of respondents were of the opinion that generic drugs are as safe as brand equivalents. A high percentage of participants supported the policy of generic substitution (n=1634; 71.4%). A significant positive correlation was demonstrated between total knowledge score and total perception score (ρ=0.267; p<0.001). Efficacy, safety and the direction of national policies and hospital regulations were the main factors affecting pharmacists' willingness to dispense generic drugs.

CONCLUSIONS

The study identified gaps in respondents' knowledge and perceptions of generic substitution. Pharmacists who are more knowledgeable in generic drugs tend to hold a more supportive attitude towards generic substitution. Although it appeared that pharmacists in China have largely accepted generic substitution, they still have concerns regarding the reliability and quality of generic drugs. The current issues need to be addressed for the realisation of the true value of generic drugs as part of the country's healthcare cost-containment strategy as well as the implementation of generic substitution policy in China.

Differences between the quality aspects of various generic and branded docetaxel formulations

Docetaxel is a widely prescribed chemotherapy drug in oncology and post expiry of its patent, the drug has been marketed as a generic by multiple manufacturers. It is also classified as a narrow therapeutic window drug. Through enhanced permeability and retention effect, polymeric micelles can passively target agents to tumor tissue, thereby decreasing toxicity of the drug in normal tissue. However, various studies have raised concerns that generic docetaxel leads to greater incidences of toxicities among patients with cancer. Thus, we herein review the pharmaceutical challenges associated with different docetaxel formulations and provide insights into the dissimilarities in the quality and safety of branded and generic docetaxel formulations. Literature review reported that 90% of the generic formulations of docetaxel contain inadequate quantity of active drug and high levels of impurities. Higher amounts of solvents such as polysorbate 80 and ethanol in docetaxel formulation lead to severe toxicities such as febrile neutropenia, hematological, and cutaneous toxicities. In most of the studies, even minor changes in excipients, solvents, unbound fraction of docetaxel were associated with adverse events, while in few, the source of docetaxel remained unidentified. One study reported incidence of febrile neutropenia due to a switch in the formulation from branded to generic. The quality, safety, and efficacy of medicines will directly affect the life of patients, and therefore, use of docetaxel formulations that guarantee safety of patients are the necessity of the hour. Being an injectable anti-cancer drug, it is important to determine the consistency of the various formulations of docetaxel globally, conduct bioequivalence studies as per the regulatory standards, taking into account the permissible limits of the excipients or the presence of such unapproved excipients.

Considerations over a Case of Suspected Therapeutic Failure in Pediatric Patients after Switching Valproate Manufacturers

Introduction: Product switching followed by suspected adverse events are common and unsettling for antiepileptic drugs. The objective of this case study was to describe the investigation performed after report of suspected therapeutic failure in pediatric patients following a switch to a different valproate manufacturer and identify strategies concerning medication management for improving therapeutic outcomes. Case description: It was reported that different pediatric patients' condition changed (agitation/ seizures) after refilling the same drug prescription (sodium valproate syrup) from a different manufacturer. Medical staff reported a suspected therapeutic failure and some units of the product batch associated with the problem were seized by the local Post-marketing Surveillance Service for investigation of potential quality deviations. The seized units were evaluated by the State's Surveillance Laboratory, nevertheless, drug potency was found to be 98.7%. Conclusion: We consider that the reported event could be associated with aspects of medication use, i.e. potential dose measurement deviations resulting from remaining of residual liquid in the cup or eventual delay at prescription refilling process and consequential - even though brief - pharmacotherapy discontinuity. Patient education and counseling by pharmacists are essential for preventing drug-related problems and enhancing positive outcomes of pharmacotherapy.

Assessment of Variation in State Regulation of Generic Drug and Interchangeable Biologic Substitutions

IMPORTANCE

Brand-name drugs, including biologics, have been the primary source of increasing prescription drug spending in the US. Each state has drug product selection laws that regulate whether and how pharmacists can substitute prescriptions for brand-name drugs with more affordable equivalents, either small-molecule generic drugs or interchangeable biologics, but the details of these laws can vary.

OBJECTIVE

To examine the variation in state drug product selection laws with regard to factors that may affect which version of a drug is dispensed.

DESIGN, SETTING, AND PARTICIPANTS

A cross-sectional analysis was performed, using a legal database, to obtain information on state laws of all states plus Washington, DC, as they existed on September 1, 2019.

EXPOSURES

Whether substitution was mandatory or permissive, patient consent was needed prior to substitution, patient notification of substitution was required independent of the drug's packaging, and/or pharmacists were protected from special risk of liability for substitution.

MAIN OUTCOMES AND MEASURES

For small-molecule and biologic drugs, descriptive statistics were generated for the 4 exposure variables. In addition, for small-molecule drugs, a generic substitution score with a maximum of 1 point was assigned for each exposure variable (range, 0-4 points), with higher scores indicating regulatory requirements limiting substitution.

RESULTS

This cross-sectional analysis of the generic drug substitution regulations in the 50 US states and Washington, DC, found that for small-molecule drugs, 19 states required pharmacists to perform generic substitution; 7 states and Washington, DC, required patient consent; 31 states and Washington, DC, mandated patient notification independent of the drug's packaging, and 24 states did not explicitly protect pharmacists from greater liability. Nine states and Washington, DC, had a generic substitution score for small-molecule drugs of 3 or higher, and 45 states had more stringent requirements for interchangeable biologic substitution, most commonly mandatory physician notification.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that there is a need for optimizing state drug product selection laws to promote generic and interchangeable biologic substitution, which may help improve medication adherence and reduce drug spending.

Comparative Outcomes of Treatment Initiation With Brand vs. Generic Warfarin in Older Patients

The anticoagulant response to warfarin, a narrow therapeutic index drug, increases with age, which may make older patients susceptible to adverse outcomes resulting from small differences in bioavailability between generic and brand products. Using US Medicare claims linked to electronic medical records from two large hospitals in Boston, we designed a cohort study of ≥ 65-year-old patients. Patients were followed for a composite effectiveness outcome of ischemic stroke or venous thromboembolism, a composite safety outcome, including major hemorrhage, and a 1-year all-cause mortality outcome. After propensity score fine-stratification and weighting to account for > 90 confounders, hazard ratios comparing brand vs. generic warfarin initiators (95% confidence intervals) for the effectiveness, safety, and all-cause mortality outcomes, were 0.97 (0.65-1.46), 0.94 (0.65-1.35), and 0.84 (0.62-1.13), respectively. Results from subgroup analyses of patients with atrial fibrillation, CHADS-VASc score ≥ 3, and HAS-BLED score ≥ 3 were consistent with the primary analysis.

A Survey of Patients' Perceptions of Pill Appearance and Responses to Changes in Appearance for Four Chronic Disease Medications

BACKGROUND

Generic versions of a drug can vary in appearance, which can impact adherence.

OBJECTIVE

To assess the preferences, perceptions, and responses of patients who experienced a change in the appearance of a generic medication.

DESIGN

Cross-sectional survey of patients from a large commercial health plan.

PARTICIPANTS

Adults receiving generic versions of lisinopril, fluoxetine, lamotrigine, or simvastatin who experienced a change in the color or shape of their pills between March 2014 and November 2015.

MAIN MEASURES

Likert-scale responses to questions concerning perceptions of generic drug safety and effectiveness, reliance on and preferences for pill appearance, and responses to pill appearance changes. Multivariable logistic regression-modeled predictors of seeking advice and adjusting use following a pill appearance change.

KEY RESULTS

Of 814 respondents (response rate = 41%), 72% relied on pill appearance to ensure they took the correct medication. A similar percentage wanted their pills to remain the same color (72%), shape (71%), and size (75%) upon refill, but 58% would not have paid a $1 premium on a $5 co-pay to ensure such consistency. Most respondents (86%) wanted their pharmacists to notify them about pill appearance changes, but only 37% recalled such notification; 21% thought they received the wrong medication, and 8% adjusted medication use. Younger respondents (18-33 vs. 50-57 years) were more likely to seek advice (odds ratio [OR] = 1.91; 95% confidence interval [CI],1.02-3.59), and respondents with lower household income (< $30,000 vs. > $100,000) were more likely to adjust medication use (OR = 3.40; 95% CI,1.09-10.67).

CONCLUSIONS

Requiring uniform pill appearance may help increase adherence but presents challenges. Standardized pharmacy notification and education policies may be a more feasible short-term solution.

Comparative effectiveness of generic and brand-name medication use: A database study of US health insurance claims

BACKGROUND

To the extent that outcomes are mediated through negative perceptions of generics (the nocebo effect), observational studies comparing brand-name and generic drugs are susceptible to bias favoring the brand-name drugs. We used authorized generic (AG) products, which are identical in composition and appearance to brand-name products but are marketed as generics, as a control group to address this bias in an evaluation aiming to compare the effectiveness of generic versus brand medications.

METHODS AND FINDINGS

For commercial health insurance enrollees from the US, administrative claims data were derived from 2 databases: (1) Optum Clinformatics Data Mart (years: 2004-2013) and (2) Truven MarketScan (years: 2003-2015). For a total of 8 drug products, the following groups were compared using a cohort study design: (1) patients switching from brand-name products to AGs versus generics, and patients initiating treatment with AGs versus generics, where AG use proxied brand-name use, addressing negative perception bias, and (2) patients initiating generic versus brand-name products (bias-prone direct comparison) and patients initiating AG versus brand-name products (negative control). Using Cox proportional hazards regression after 1:1 propensity-score matching, we compared a composite cardiovascular endpoint (for amlodipine, amlodipine-benazepril, and quinapril), non-vertebral fracture (for alendronate and calcitonin), psychiatric hospitalization rate (for sertraline and escitalopram), and insulin initiation (for glipizide) between the groups. Inverse variance meta-analytic methods were used to pool adjusted hazard ratios (HRs) for each comparison between the 2 databases. Across 8 products, 2,264,774 matched pairs of patients were included in the comparisons of AGs versus generics. A majority (12 out of 16) of the clinical endpoint estimates showed similar outcomes between AGs and generics. Among the other 4 estimates that did have significantly different outcomes, 3 suggested improved outcomes with generics and 1 favored AGs (patients switching from amlodipine brand-name: HR [95% CI] 0.92 [0.88-0.97]). The comparison between generic and brand-name initiators involved 1,313,161 matched pairs, and no differences in outcomes were noted for alendronate, calcitonin, glipizide, or quinapril. We observed a lower risk of the composite cardiovascular endpoint with generics versus brand-name products for amlodipine and amlodipine-benazepril (HR [95% CI]: 0.91 [0.84-0.99] and 0.84 [0.76-0.94], respectively). For escitalopram and sertraline, we observed higher rates of psychiatric hospitalizations with generics (HR [95% CI]: 1.05 [1.01-1.10] and 1.07 [1.01-1.14], respectively). The negative control comparisons also indicated potentially higher rates of similar magnitude with AG compared to brand-name initiation for escitalopram and sertraline (HR [95% CI]: 1.06 [0.98-1.13] and 1.11 [1.05-1.18], respectively), suggesting that the differences observed between brand and generic users in these outcomes are likely explained by either residual confounding or generic perception bias. Limitations of this study include potential residual confounding due to the unavailability of certain clinical parameters in administrative claims data and the inability to evaluate surrogate outcomes, such as immediate changes in blood pressure, upon switching from brand products to generics.

CONCLUSIONS

In this study, we observed that use of generics was associated with comparable clinical outcomes to use of brand-name products. These results could help in promoting educational interventions aimed at increasing patient and provider confidence in the ability of generic medicines to manage chronic diseases.

The adoption of generic immunosuppressant medications in kidney, liver, and heart transplantation among recipients in Colorado or nationally with Medicare part D

The transplant community is divided regarding whether substitution with generic immunosuppressants is appropriate for organ transplant recipients. We estimated the rate of uptake over time of generic immunosuppressants using US Medicare Part D Prescription Drug Event (PDE) and Colorado pharmacy claims (including both Part D and non-Part D) data from 2008 to 2013. Data from 26 070 kidney, 15 548 liver, and 6685 heart recipients from Part D, and 1138 kidney and 389 liver recipients from Colorado were analyzed. The proportions of patients with PDEs or claims for generic and brand-name tacrolimus or mycophenolate mofetil were calculated over time by transplanted organ and drug. Among Part D kidney, liver, and heart beneficiaries, the proportion dispensed generic tacrolimus reached 50%-56% at 1 year after first generic approval and 78%-81% by December 2013. The proportion dispensed generic mycophenolate mofetil reached 70%-73% at 1 year after generic market entry and 88%-90% by December 2013. There was wide interstate variability in generic uptake, with faster uptake in Colorado compared with most other states. Overall, generic substitution for tacrolimus and mycophenolate mofetil for organ transplant recipients increased rapidly following first availability, and utilization of generic immunosuppressants exceeded that of brand-name products within a year of market entry.