Economic Cost of the Waste of Anti-inflammatory and Analgesic Drugs in Mexico City

Abstract

Anti-inflammatory and analgesic medications (AAMs) are widely used in Mexico and the rest of the world. Their excessive acquisition can lead to waste, representing an unnecessary expense for families and the public health system. The aim of this study was to estimate the economic cost of the waste of unused AAMs collected by the National System for the Collection of Residues of Containers and Medications (SINGREM, the acronym in Spanish) in Mexico City during 2019. Data from SINGREM on discarded AAMs in Mexico City were classified by the type and quantity of drug, pharmaceutical dosage form, origin, dose, and the complete or incomplete condition of the package. The unitary cost for each medication was based on public tenders of the Mexican Social Security Institute (IMSS) for the public sector and the prices in large drug store franchises for the private sector. A decision-making model was constructed to appraise the total cost of discarded AAMs. The economic cost of the 48924 units of discarded AAMs in SINGREM containers in Mexico City during 2019 was approx. USD$143500, of which over USD$127000 corresponded to the private health sector. The current findings evidence an enormous accumulation of unneeded or expired AAMs in Mexico City. According to the present data, the cost of such waste is substantial. The estimated cost was 8-fold higher for discarded medications originating from the private versus the public healthcare sector. It is important to implement measures to prevent this waste and increase awareness of the consequences of inadequate drug disposal.

INTRODUCTION

In recent years, the high level of medications in the environment has alarmed scientists, healthcare providers, and politicians around the world. This situation could lead to an adverse ecological impact,¹⁾ a risk to the health and safety of the population,²⁾ and a waste of family and institutional resources.³⁾ One of the important causes of the presence of these pharmaceutical products in the environment is the accumulation of unneeded and expired drugs in homes,⁴⁾ leading to their eventual disposal. Although various studies have broached this subject, it is crucial to focus on the specific economic cost of the waste of medications as a first step in creating awareness of the magnitude of the problem.

Prescribed or over-the-counter drugs are wasted when they have expired, are contaminated, or are no longer needed. They can accumulate in homes, be returned to a drug store or healthcare professionals, or be disposed of correctly (in special collection bins) or incorrectly (in domestic garbage or public drainage systems).^3,5) Among the reasons for the accumulation of unused medicine are unnecessary prescriptions, low adherence to treatment, irrational dispensation⁵⁾ and self-medication.⁴⁾

To our knowledge, the costs associated with the accumulation of unused drugs have been evaluated in only a few reports.^3,6–9) Evidence from different regions of the world suggests that such costs are high. For instance, it was estimated by means of a questionnaire in 2001 that the population in Saudi Arabia and other countries of the Persian Gulf spends around 150 million U.S. dollars (USD$) annually on unused medications.⁶⁾ More recently, based on a collection of wasted drugs from July to August of 2008 in a certain hospital in Australia, the expense was appraised at approx. 1308 Australian dollars per patient annually.⁸⁾ A study in California, U.S.A., carried out between April and June of 2011 determined that 42% of prescribed drugs were not consumed. The projected nationwide cost was 117 billion USD$.⁷⁾ Finally, research conducted in Vienna, Austria, from April to June of 2016 described the cost to consumers at over 37.65 million euros (€21 per inhabitant) for the domestic accumulation of unneeded and expired medications.³⁾

Mexico instituted the National System for the Collection of Residues of Containers and Medications (SINGREM, the acronym in Spanish) in 2007. Its mission is to collect and properly dispose of medications considered as waste, either because they are unneeded by individuals or expired.¹⁰⁾ Several studies agree that most common over-the-counter drugs are analgesics and anti-inflammatory medications (AAMs).^11–13) Additionally, in research conducted from 2012–2013 in the metropolitan area of Monterrey (Nuevo Leon, Mexico), the majority of expired medications were found to be nonsteroidal anti-inflammatory drugs (NSAIDs).¹⁴⁾

The irrational distribution and purchase of drugs can lead to a large unnecessary expense for the population. This is especially true for AAMs, as they represent the majority of discarded pharmaceutical products worldwide.¹⁵⁾ However, there is little information available on the costs associated with such waste.

The aim of the current contribution was to estimate the economic cost of discarded AAMs in SINGREM containers in Mexico City during 2019 and analyze the proportion of the waste (in units and USD$) originating from the public and private health sector. The results are provided to promote the development and implementation of strategies for a more rational distribution and purchase of these medications.

MATERIALS AND METHODS

Study Design and Source of Data

This was a retrospective study based the records of the SINGREM of AAMs collected in the 16 districts of Mexico City in 2019. The data was expressed in units, considered as any package or bottle (incomplete due to partial consumption or complete) of analgesics or anti-inflammatory drugs, defined in accordance with the National List of Essential Medicines (Compendio Nacional de Insumos para la Salud in Spanish). Additionally, information was obtained about the generic name of the discarded medication, the location of the collection container, the pharmaceutical dosage form, the expiration date, the dose, and the origin (the public or private health sector, or free medical samples).

The SINGREM has special containers distributed at strategic points (in drug stores, hospitals, clinics, and other places) across the country for the disposal of unwanted medications accumulated in homes. After being collected, these pharmaceutical products are taken to operative centers where qualified personnel analyze them to establish a statistical record. Subsequently, the waste material is sent to its final destruction. The entire process is regulated by an operative protocol guaranteeing proper disposal of pharmaceutical waste.¹⁰⁾

Evaluation of Economic Costs

The direct cost of discarded AAMs originating in the public or private health sector was estimated, considering only the cost of acquisition. In the event the medication came from the public sector, the unitary cost of each type of AAM was defined in accordance with the public tenders in 2019 on the web page of the Mexican Social Security Institute (IMSS, the acronym in Spanish). If they came from the private sector, the cost was fixed at the average price in the two most popular drug store franchises in Mexico City. Free medical samples were not considered in the economic evaluation. If the unitary cost data for the year 2019 was not found, data reported in the three previous years were used and adjusted to the year 2019, using an adjusting ratio of 0.05 according to the method described by Muenning.¹⁶⁾ The information on the AAMs was organized and classified by generic name and origin, and the quantity of each drug was determined.

The monetary value of the discarded AAMs was expressed in USD$, based on the average exchange rate in 2019 of one USD$ = 19.2574 Mexican pesos.¹⁷⁾ The total annual cost of the waste of each type of AAM was calculated according to the valuation of healthcare resources described by Muenning¹⁶⁾; quantity and price of each resource are multiplied together, and then summed with the following formula:

  

Where #CUD_public = the number of complete units of a discarded AAM annually, originating from the public sector; UC_public = the unitary cost of a certain AAM in the public sector; #IUD_public = the number of incomplete units of a discarded AAM annually, originating from the public sector; #CUD_private = the number of complete units of a discarded AAM annually, originating from the private sector; UC_private = the unitary cost of a certain AAM in the private sector; #IUD_privado = the number of incomplete units of a discarded AAM annually, originating from the private sector; 0.5 = the factor considered for incomplete units, assuming an average of 50% consumption.

Economic Model

A decision-making model was constructed to represent the process of the disposal of drugs (Fig. 1), contemplating their origin (in the public or private sector), the correct or incorrect manner of disposal, and the complete or incomplete condition of the unit. The model allowed for an estimation of the cost per unit of each discarded medication. A Monte Carlo simulation was carried out to examine the cost of different hypothetical cohorts of discarded units. It was assumed that medications are properly discarded in Mexico in 30% of the cases.¹⁸⁾

Fig. 1. Decision-Making Model of the Medication Disposal Process

Statistical Analysis

A descriptive analysis was made of the sample and of the costs associated with the waste of AAMs, based on the frequency distribution of the central tendency and dispersion.¹⁹⁾ A sensitivity analysis was made of the variables subject to uncertainty (unitary costs, proportion of used/unused discarded units, and proportion of correct/incorrect disposal and public/private sector origin), evaluating the effect on the total cost of the base case when utilizing an interval of variation of ±7%.

RESULTS

In the 868 disposal containers distributed throughout Mexico City, 54338 units of AAMs were collected in 2019. Among the discarded drugs, the three most abundant were acetaminophen (33.94%), acetylsalicylic acid (ASA) (17.24%), and diclofenac (10.54%), while the least abundant was morphine (0.03%) (Fig. 2).

Fig. 2. Discarded AAMs Collected in SINGREM Containers in Mexico City during 2019

Table 1 portrays the distribution of the pharmaceuticals collected by the SINGREM. Solid pharmaceutical dosage forms constituted the greatest number of discarded units (86.9%), followed by liquids (11.5%), semisolids (1.5%), and aerosols (0.02%).

Table 1. Units of Discarded Medications in the SINGREM Containers in Mexico City during 2019, Classified by Pharmaceutical Dosage Form

Pharmaceutical dosage form	Discarded units	Percentage (%)
Solid drugs	47229	86.917
Tablets or pills	35649	65.606
Capsules	7982	14.690
Coated tablets	2636	4.851
Suppositories	595	1.095
Granules	313	0.576
Patches	54	0.099
Liquids	6259	11.519
Syrups	998	1.837
Solutions	3704	6.817
Suspensions	1553	2.858
Lotions	4	0.007
Semisolids	840	1.546
Gels	555	1.021
Creams	273	0.502
Ointments or salves	12	0.022
Aerosols	10	0.018
Total	54338	100

A very high percentage (91.5%) of the units of discarded AAMs were expired. Well over half (69.7%) were complete and the rest (30.3%) incomplete. The majority (56.1%) originated from the public health sector, while about one third (33.0%) came from the private sector, and around one tenth (10.9%) were free medical samples. The cost of the discarded AAMs was estimated at approx. USD$15700 for medications from the public sector and approx. USD$127700 for those from the private sector, for a total of over USD$143000 in waste collected by the SINGREM in Mexico City during 2019 (Table 2).

Table 2. Estimated Costs Associated with the AAMs Collected by the SINGREM in Mexico City during 2019

Drug	Total estimated cost in the public sector (USD$)	Total estimated cost in the private sector (USD$)	Total estimated cost (USD$)	Interval of costs (USD$)
Acetaminophen	1460.22	39782.77	41242.98	12477.71–70008.26
ASA	2822.98	2194.79	5017.76	3465.35–6570.17
Betamethasone	16.33	3551.42	3567.75	2559.41–4576.10
Buprenorphine	1325.24	2809.50	4134.75	2979.41–5290.08
Celecoxib	5091.09	2176.77	7267.86	6556.13–7979.59
Diclofenac	512.32	18796.13	19308.44	3463.63–35153.26
Etoricoxib	496.82	3114.31	3611.13	2304.44–4917.82
Ibuprofen	256.24	12182.44	12438.68	3924.41–20952.95
Indomethacine	1986.25	4577.34	6563.60	3716.29–9410.91
Ketorolac	46.64	8248.19	8294.83	2625.47–13964.20
Lysine clonixinate	90.38	1118.83	1209.21	843.86–1574.56
Morphine	116.85	85.99	202.83	154.09–251.57
Naproxen	830.72	7274.18	8104.91	4303.57–11906.25
Piroxicam	385.05	2097.34	2482.39	1242.72–3722.05
Tramadol	311.81	19746.19	20058.01	3202.12–36913.90
Total	15748.95	127756.19	143505.14	53818.61–233191.67

Based on the decision-making model of economic analysis, the average cost per unit of discarded medication was USD$2.94 (Fig. 3). According to the tendency of the cohorts of units of AAMs in the Monte Carlo simulation (Fig. 4), it was possible to estimate that the total wasted units of discarded AAMs correctly and incorrectly could have reached a little over 163000 units in Mexico City during 2019, which is equivalent to almost half a million dollars (USD$479953).

Fig. 3. Simulated Distribution of Cost per Unit of Discarded AAMs

Mean, USD$2.94; median, USD$2.94; Interval: Min USD$2.62–Max USD$3.23, 2.5% percentile: USD$2.74, 97.5% percentile:3.12. *Vertical lines denote the 95% confidence interval.

Fig. 4. Results of the Monte Carlo Simulation

Total cost of unused drugs in Mexico City during 2019, considering different quantities of units of discarded AAMs, either correctly or incorrectly.

Regarding the sensitivity analysis, the parameters with the greatest influence on the overall cost of the model were: 1) the probability that a drug came from the public health system, 2) the cost of a complete unit (unused) coming from private health services, 3) the probability that a complete unit (unused) came from private health services, and 4) the cost of an incomplete unit (used) coming from private health services (Fig. 5).

Fig. 5. Multivariate Sensitivity Analysis

Tornado diagram.

DISCUSSION

To our knowledge, this is the first study in Mexico on the cost of discarded medications, using a database with an ample array of information from the national system dedicated to collecting such waste material. We found that over 54000 units of AAMs were collected in the containers of the SINGREM in Mexico City during 2019, with an associated cost estimated to be over USD$143500 (free medical simples not included).

Regarding drug waste according to their pharmaceutical dosage form, solid, liquids and semisolids were the most frequently discarded in our study. These findings are consistent with a study focused on drug wastage in general in Monterrey, Mexico,¹⁴⁾ and other studies conducted in other parts of the world, such as North East Ethiopia,²⁰⁾ U.S.A.,⁷⁾ and India,⁹⁾ among other countries.²¹⁾ According to these studies, this may be due to the fact that solid pharmaceutical dosage forms, especially oral ones, are the most used due to their simplicity and comfort for the patient.^7,9)

Not surprisingly, acetaminophen, ASA, and diclofenac represented the greatest quantity of AAMs during the year of the current investigation, which is in agreement with the patterns described in the literature of the prescription of NSAIDs in Latin America, Africa, Iran, and other countries of the Middle East. Acetaminophen, ASA, and diclofenac were the most frequently prescribed anti-inflammatory agents in the general population in such regions, as well as in the geriatric and pediatric patients.^22–24) It has been posed that the high prevalence of discarded anti-inflammatory drugs might derive from a steady increase in the geriatric population and the tendency of the elderly to use a greater amount of NSAIDs compared to other age groups in the population.¹⁴⁾ Whatever the cause may be of the high prevalence of the prescription and purchase of AAMs, the focus of the current contribution is the tendency of these drugs to accumulate in homes. Apart from the unnecessary expense and the problem of correct disposal to avoid damage to the environment, this accumulation implies the risk of accidental toxicity and poisoning in children.^14,25) Additionally, we found that most units of discarded AAMs were expired and complete, indicating an alarming economic waste and a lack of patient adherence to prescribed drug regimens.

The present findings represent the first step in the investigation of the underutilization of acquired medications and the associated costs in big cities of Latin America (e.g., Mexico City). Regarding the accumulation of unused drugs by the general public, among the several contributing factors described by Makki and Chiatti are a lack of adherence (a multifaceted problem), the death of a patient, the deterioration of the pharmaceutical product, the loss of medications, and overbuying due to a fear of shortage. Moreover, certain practices by health providers encourage the accumulation of unused drugs: the prescription of drugs with repeated refills and prolonged use or of overly large capsules or pills, the application of treatments based on polypharmacy and/or complicated regimens, a continuous change of therapies, and insufficient professional support to patients.^5,26)

A key finding of the present study is that the majority of discarded AAMs originated in the public healthcare system, probably at least in part due to an institutional policy of not purchasing medications with combined active pharmaceutical ingredients. Therefore, the prescription of treatment regimens that require the combined medications in the public health system implies the provision of various individual drugs to make the combination, which leads to a greater volume of waste in the long run. A similar relation between waste and the prescription of combined medications in the public health system was reported by Poblano-Verástegui et al. in their investigation of polypharmacy.²⁷⁾

A high percentage of discarded AAMs originated from the private sector as well. Apart from the inadequate and irrational prescription of AAMs, an unregulated factor in Mexico tends to encourage the purchase of these medications: discounts offered by drug store chains on over-the-counter drugs to encourage customers to buy additional items outside of their shopping list, obviously contributing to their accumulation and posterior disposal. Moreover, there has been an increase in the frequency of commercials with special offers or discounts for over-the-counter drugs on social networks, applications, television, and the radio, with AAMs often included in the promotions. Also of concern is the 10% of free medical samples of AAMs found in the discarded medications, indicating either their dispensation to patients who do not require them or a failure to distribute them. Because AAMs are irrationally prescribed, dispensed, commercially promoted, acquired, and/or used, they tend to accumulate in homes, as evidenced by two aspects of the discarded units of AAMs: approx. 91% had an expired status and approx. 69% were completely unused. According to our findings, the resulting cost to the consumer or public/private health care system is high, reaching a cost of waste in one year of more than USD$143500 in Mexico City.

Even though the majority of the AAMs collected by the SINGREM in 2019 originated from the public sector of the health system, those coming from the private sector represented an 8-fold higher cost (approx. USD$15700 vs. approx. USD$127700, respectively), which implies an impact on out-of-pocket spending. This could owe itself to the acquisition of brand-name rather than generic drugs in the private sector. Indeed, reports have described the tendency of doctors in private practice to prescribe brand names,²⁸⁾ despite the requirement by Mexican law for physicians to prescribe drugs by their generic name.²⁹⁾ Another factor probably involved in the much greater cost of discarded medications originating from the private sector is the existence of big differences in prices between large drug store chains. Although the cost of discarded medications originating from the public sector is lower, the economic waste is nonetheless a burden on a system in dire need of the proper channeling of its resources to attend to the public health priorities of the Mexican population.

The decision-making model of the drug disposal process and the Monte Carlo simulation allowed for a calculation of the average cost per unit discarded in Mexico City, being USD$2.94. Based on this standard, it was possible to estimate the cost of correctly and incorrectly discarded AAMs, projecting from the total of 163000 units of discarded AAMs. The overall cost of wasted AAMs in Mexico City in 2019 would then probably be almost half a million USD$, which constitutes 0.0047% of the budget allocated to the public health system in Mexico in 2022.³⁰⁾ The percentage is small, but the quantity of funds is substantial and could be assigned to resolving important health problems, either through campaigns of prevention or medical treatments. For example, half a million USD$ is sufficient to cover the expenses of 111711 mammograms in the IMSS.³¹⁾

The first step for minimizing costs associated with drug waste is evaluating its impact, which may be relevant even in single-center studies.³²⁾ For this reason, one of the strengths of this study is that it evaluated the economic impact of AAMs waste in one of the largest cities in the world. The present findings demonstrate a high cost associated with wasted medications when evaluating only AAMs in Mexico City for one year. It is urgent to establish public policies and educational strategies directed at healthcare professionals and the general population to create greater awareness not only of the economic consequences but also the environmental and health concerns involved in the accumulation of unneeded drugs and the improper disposal of the same.

The main limitation of the current contribution is the probable underestimation of the wasted AAMs. Although a conservative figure was assigned to the properly discarded drugs (30% of AAMs) before the pandemic, based on the appraisal of the National Chamber of the Pharmaceutical Industry (Cámara Nacional de la Industria Farmacéutica) in 2021,¹⁷⁾ the variable of the correct or incorrect disposal does not have a significant impact on the result of the Monte Carlo simulation, according to the sensitivity analysis. Nevertheless, two factors likely led to an underestimation of wasted AAMs: 1) the relatively limited number of containers of SINGREM in public spaces in the large metropolitan area of Mexico City, and 2) the increased purchase of medications by the general population stemming from the coronavirus disease 2019 (COVID-19) pandemic.

In conclusion, almost 70% of the units of discarded AAMs and collected by SINGREM in Mexico City during 2019 were complete (full packages) and over 90% were expired. Interestingly, most of the units originated from the public health system, although there was an 8-fold greater cost of the total number of units coming from the private sector. Thus, 89.02% of the total USD$143505 in wasted medications corresponded to the private sector of the health system. Based on a projection of the correctly and incorrectly discarded units of AAMs in Mexico City during 2019, the total cost of wasted medications was probably around half a million USD$.

Conflict of Interest

The authors declare no conflict of interest.

Supplementary Materials

This article contains supplementary materials.

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