When I use a word . . . Overstocking medicines

Problems with drug stocks

A drug stock-out12 is the complete absence of a medicine from the shelves of any outlet that would be expected to stock it, typically a pharmacy. Drug stock-outs overlap to some extent with drug shortages, which refer to more widespread non-availability of medicinal products, and it isn‘t always clear when a stock-out that has spread to more than one pharmacy can be regarded as a drug shortage. However, the indicators described by the WHO,3 designed to help pharmacies avoid both drug stock-outs and overstocking, were devised having in mind countries in which pharmacies’ procurement and supply management systems are organised nationally; in such cases a national shortage can be regarded as a national stock-out, to be dealt with in the same ways as local stock-outs. In other countries one would typically regard stock-outs as being limited to numbers of pharmacies far short of being national.

The WHO defines a stock-out as “any time when, at a defined moment in a given inventory, a needed medicine item is not in stock and orders or prescriptions cannot be filled.” Although some of the factors that lead to drug shortages may also cause drug stock-outs, more commonly stock-outs are owing to local factors.

Overstocking

On the other side of the coin, the WHO has defined overstocking as “Excess stocks of products, which exceed current demand at a given time.”3

In order to explore aspects of overstocking, I have searched for the term “overstock*” in PubMed, without restrictions. Of 149 resultant hits, 35 were relevant to, or at least mentioned, overstocking of medicines. Many of the other publications dealt with overstocking of animals, both wild and farm animals (mostly cattle), fish, or forestry and plants. Some dealt with overstocking of surgical, pathological, and personal protective equipment, medical devices, condoms, blood, and even medical office equipment. In one case “overstocking” referred to compression stockings for treating venous ulcers,4 which don’t actually seem to have been overstocked.

Like the literature on stock-outs, most of the publications came from Africa: Ethiopia (8), Uganda (5), South Africa (2), and Kenya, Nigeria, and South Sudan (1 each). However, there was wider distribution of the others. Six came from Asian countries: India (3), Pakistan (2), and Taiwan (1); four from South or Central America or the Caribbean: Argentina, Brazil, Haiti, and Mexico; four from European countries: France, Portugal, Spain, and the UK; two from Saudi Arabia; and one from an international organisation, Management Sciences for Health.

Wastage

Overstocking leads to wastage. In one study in Ethiopia during one month the total monetary value of wasted medicines, attributable to overstocking, was just over 5% of budget, and during 2011, 2012, and 2013 wastage of medicines amounted to 7.6%, 6.4%, and 3.1% respectively; expired medicines alone accounted for 97% of the total value.5 Overstocking was attributed to inaccurate stock quantification, incorrect forecasting of needs, improper use or lack of electronic stock management, and abrupt changes in the treatment regimen.

High wastage rates associated with poor inventory control practice can be owing to lack of integrated pharmaceutical logistics system training, poor management support, supply of pharmaceuticals nearing expiry,6 job dissatisfaction, and high staff turnover.7

Medicines affected

Most of the papers I surveyed dealt with the general problem of overstocking,, but some considered specific groups of drugs, particularly anaesthetics,8 antibiotics,910 antimalarial drugs,1112 antiretroviral drugs,131415 and antituberculosis drugs.1617 The appearance in the list of the last three types of drugs is not surprising—they were the subject of the WHO’s 2011 guidance on avoiding stock-outs and overstocking.3

Vaccines18192021 are particularly susceptible to overstocking, because while enough vaccine needs to be obtained to serve the community, it is hard to predict exactly how much will be needed, and when all of those needing immunisation, or wanting to be vaccinated, have been treated the remaining vaccine is of no use and is therefore wasted. In one study in 12 districts across Pakistan, stocks of covid-19 vaccines were too high and needed to be reduced by 36-43%.18 Careful modelling and redistribution of stock within the districts from areas of low efficiency to areas of high efficiency would be beneficial in such cases.22 In one study, doing this covered 75% of drug stock-outs.23

Overstocking of antibiotics can also be important, because it can contribute to overuse or misuse,24 which would be expected, in turn, to increase the risk of bacterial resistance.

Avoiding overstocking

Several different methods have been used to minimise the risk of overstocking. In countries that involve national procurement and supply systems, the WHO’s indicators3 should be helpful in avoiding overstocking, at least of the three main types of medicines the guidance refers to, but probably also other medicines.

Co-ordinating all available data is an important method of stock control in avoiding overstocking. In one study different sources of information were combined using a cloud-based tracking system in over 5000 patients and over 500 different types of medicines, in an effort to reduce stock-outs and overstocking. The sources used were: numbers of patient admissions, diagnoses, delivery information, laboratory test reports, and inventory information from the various stores where medicines were kept.25

Other systems that have been used include a systems dynamics simulation model of the downstream supply chain26 and methods of avoiding stocking products with short expiry dates.27 Redistribution guidelines are also available.28

Prioritising

No medicine is immune to the possibility of overstocking, but priorities can be identified. The so-called ABC-VED system may be helpful in doing this. The system depends on two classifications, based on cost and need. The cost analysis is based on the Pareto Principle, enunciated by the economist Vilfredo Pareto, that in the case of pharmaceuticals 10% of all items consume about 70% of budget (Group A), 20% consume 20% (Group B) and 70% consume 10% (Group C). The need analysis is based on how important an item is, whether vital, essential, or merely desirable (the VED system).

Combinations of these types can be used in determining priorities. In one study items were organised in three categories—I: AV+BV+CV+AE+AD; II: BE+CE+BD; and III: CD.29 The ABC-VED system has been used to optimise pharmaceutical stocks in India30 and Ethiopia.31

A final thought

Rosalind, in As You Like It, about to marry Orlando, wonders whether one can desire too much of a good thing. As far as medicinal stocks are concerned one certainly should not. That is why the targets that the WHO recommends for its indicators are so stringent—precisely 100% or 0% depending on the indicator. If, for example, under 100% of orders are delivered in full and on time, that indicates that there is a risk of a stock-out; more than 100% indicates a risk of overstocking.

Stock-outs and overstocking are the Scylla and Charybdis of pharmacy practice.