Pharmacoepidemiology and Drug Safety
ORIGINAL ARTICLE
OPEN ACCESS
Impact of Antibiotic Shortages on Antibiotic Utilisation in
the Community
Maarten Lambert1,2
| Katja Taxis2 | Lisa Pont1
1Graduate School of Health, University of Technology Sydney, Sydney, Australia
| 2Unit of Pharmacotherapy, Epidemiology and Economics, Groningen
Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands
Correspondence: Maarten Lambert (m.lambert@rug.nl)
Received: 19 August 2024 | Revised: 26 December 2024 | Accepted: 5 January 2025
Funding: The authors received no specific funding for this work.
Keywords: antibiotics | community setting | drug shortages | drug utilisation | primary care
ABSTRACT
Background: Drug shortages are an increasing and worldwide problem. Oral antibiotics are one of the most used medicines
worldwide and have recently been affected by drug shortages. Despite this, little is known about the impact of antibiotic shortages on prescribing practices.
Aim: To explore the impact of oral antibiotic shortages on national antibiotic utilisation.
Methods: A cross-­sectional study of oral antibiotic shortages and antibiotic utilisation was conducted using Australian reimbursement and regulatory data from January 2022 to December 2023. All nationally reimbursed oral antibiotics were included
in the study. The number and duration of reported antibiotic shortages per product were determined for each active ingredient.
The clinical impact was assessed using national utilisation in Defined Daily Doses per 100 000 inhabitants. Changes in trends
were analysed using Joinpoint regression.
Results: Shortages were reported for eighteen of the twenty-­one (86%) oral antibiotics reimbursed in Australia. For ten active
ingredients, shortages did not coincide with changes in utilisation data. No clear relation between the number and duration of
shortages and impact on utilisation was observed. Changes in utilisation coinciding with shortages were observed for eight active
ingredients. For cefaclor (−20% decrease in utilisation) and roxithromycin (−26% decrease), the impact of shortages is most clearly
reflected by decreases in utilisation. For the other six, minor changes in utilisation were observed coinciding with shortages.
Conclusions: Antibiotic shortages were common in Australia during 2022 and 2023. The impact of shortages differs per antibiotic, for some antibiotics there are shortages coinciding with declines in utilisation. For others, shortages occur without apparent
changes in utilisation.
1   |   Introduction
Drug shortages are a common and increasing problem worldwide [1, 2]. In American hospitals alone, responding to shortages was reported to cost $359 million yearly, with over $200
million extra in additional labour costs [3]. Amongst all drug
classes, antibiotics are most affected by shortages [4]. The risk
of antibiotic shortages is substantial as the supply chain for
antibiotics is fragile [1, 5]. Moreover, shortages of antibiotics
and oncology medicines were reported as most commonly associated with poor patient outcomes [6]. The impact of shortages varies, including delays of care, suboptimal treatment,
Prior postings and presentations: This research has not been published or presented elsewhere. It has been accepted for presentation at the 2024 International Conference on
Pharmacoepidemiology & Therapeutic Risk Management.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the
original work is properly cited and is not used for commercial purposes.
© 2025 The Author(s). Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.
Pharmacoepidemiology and Drug Safety, 2025; 34:e70107
https://doi.org/10.1002/pds.70107
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Summary
• Antibiotic shortages were reported for 86% of all oral
antibiotics available in Australia between 2022 and
2023.
• For ten active ingredients, shortages did not coincide
with changes in national utilisation.
• A reduction in national utilisation, coinciding with a
period of reported shortages, was observed for eight
active ingredients; cefaclor and roxithromycin showed
the largest decreases, six other active ingredients
showed minor reductions in utilisation.
• There is no clear relation between the number and duration of shortages and the impact on utilisation data.
treatment failure and death [7]. Additionally, shortages of antibiotics may lead to treatment with alternative antibiotics that
may have a greater impact on the development of antibiotic
resistance [2, 4, 8].
The impact of shortages on prescribing practices and patients
in the community setting is unknown. Only a limited number of studies have been performed on the relation between
shortages and usage trends. These studies focus on the hospital setting [9]. In this setting, antibiotic shortages have resulted in significant decreases in antibiotic usage, increased
use of alternatives and increased costs [9–12]. Interestingly,
the resolution of shortages does not always result in utilisation returning to pre-­shortage patterns. In one study, hospital
shortages were resolved, but usage returned to baseline levels
only for some but increased levels for other active ingredients
[10]. Moreover, shortages in one antibiotic can lead to changes
in the utilisation of others as clinicians seek alternatives for
the agent in shortages. Such alternatives may be less effective
or associated with increased development of antibiotic resistance [2].
including reporting information on drug shortages [17]. Drug
manufacturers must report shortages to the TGA under
Australian legislation [17]. The TGA defines shortages as “the
supply of a drug is not likely to meet the normal or projected consumer demand within Australia at any point during the next six
months” [18]. This definition aligns with a definition posed by
the World Health Organization on shortages [19]. Shortages are
reported at the individual product level.
2.2   |   Eligible Antibiotics
Australia has a national government-­
f unded reimbursement
system, the Pharmaceutical Benefits Scheme (PBS), for drugs
prescribed in the community setting or on discharge from hospitals [20, 21]. Patients pay a co-­payment for each medicine listed
on the PBS, and the Australian government covers any remaining cost. Drugs are listed on the national reimbursement schedule at the individual product level [22]. The PBS includes 21 oral
antibiotics (ATC class J01, Table 1). Multiple products may be
included in the reimbursement system for one active ingredient
with different brands, strengths, or formulations. All oral antibiotics on the PBS were included in the study. Parenteral and
topical antibiotics were excluded from the analysis.
2.3   |   Data Sources
2.3.1   |   Antibiotic Shortages
Shortages occurring in Australia are published in the TGA
Medicine Shortages reports database [18]. We extracted brand
names, active ingredients, ATC codes, formulations, and start
and end dates for all shortages of oral PBS-­listed antibiotics occurring during the study period.
2.3.2   |   Antibiotic Utilisation
Management of shortages is organised differently amongst countries, and even within countries, the clinical impact of shortages
may differ [4, 10, 13, 14]. In the community setting, there are no
reports on the impact of antibiotic shortages on antibiotic utilisation. Yet, as most antibiotics are used in the community setting [15, 16], exploring the impact of shortages in this setting is
particularly relevant. In this setting, oral antibiotics are mainly
used [15, 16]. Hence, this research aims to explore the impact of
oral antibiotic shortages on national antibiotic utilisation.
The Australian government provides aggregate data for all
drugs listed on the PBS. These data are publicly available and include data for all medicines listed on the PBS, in irrespective of
co-­payment status [23]. National utilisation data for all products
of the eligible antibiotics were extracted as the number of dispenses per month per antibiotic product. These data were then
aggregated at the antibiotic active ingredient level (ATC level 5).
2   |   Methods
The number and duration of antibiotic shortages in days per
product were determined for each active ingredient. Antibiotic
utilisation data were expressed as Defined Daily Doses per
100 000 inhabitants [23, 24]. Population data retrieved from
the Australian Bureau of Statistics were quarterly published.
Quarterly population changes were converted to monthly
population changes [25]. Data on shortages and drug utilisation were presented visually. Joinpoint regression was used
to analyse changes in antibiotic utilisation [26]. The impact of
shortages on utilisation was determined visually by assessing
whether changes in utilisation coincided with shortages of the
This was a cross-­sectional study of oral antibiotic shortages
and antibiotic utilisation in Australia from January 2022 to
December 2023.
2.1   |   Drug Shortages
A national government body, the Therapeutic Goods
Administration (TGA), regulates medicines in Australia,
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2.4   |   Analysis
Pharmacoepidemiology and Drug Safety, 2025
TABLE 1    |    Oral antibiotic products available on the national reimbursement schedule.
Antibiotic class (ATC level 3)
Antibiotics (ATC level 5)
Tetracyclines (J01A)
Beta-­lactam antibacterials, penicillins (J01C)
Doxycycline (J01AA02); mlinocycline (J01AA08)
Amoxicillin (J01CA04); phenoxymethylpenicillin (J01CE02); dicloxacillin
(J01CF01); flucloxacillin (J01CF05); amoxicillin + clavulanic acid (J01CR02)
Other beta-­lactam antibacterials (J01D)
Cefalexin (J01DB01); cefaclor (J01DB04); cefuroxime (J01DC02)
Sulfonamides and trimethoprim (J01E)
Trimethoprim (J01EA01); trimethoprim + sulfamethoxazole (J01EE01)
Macrolides, lincosamides and streptogramins
(J01F)
Azithromycin (J01FA10); clarithromycin (J01FA09); erythromycin
(J01FA01); roxithromycin (J01FA06); clindamycin (J01FF01)
Quinolone antibacterials (J01M)
Ciprofloxacin (J01MA02); norfloxacin (J01MA06)
Other antibacterials (J01X)
Metronidazole (J01XD01); nitrofurantoin (J01XE01)
active ingredient. For this analysis, the dependent variable was
DDD/100,000 inhabitants, and the independent variable was the
time in months; First-­Order Autocorrelation was estimated according to Hincapie-­Castillo and Goodin [27]. Significance for
the Bonferroni adjustment method was set at p < 0.05. Joinpoint
analysis was preferred over an Interrupted Time Series analysis
as the multiple shortages per active ingredient prevented having
clear start and endpoints of the interruption. Joinpoint regressions allow for analysis without a preconceived notion of where
shifts in trends might occur [27].
2.5   |   Ethical Approval
Ethical approval was not required as all data is publicly available.
3   |   Results
Shortages were reported for eighteen of the twenty-­one (86%)
oral antibiotic active ingredients listed in the national reimbursement system during the study period. In total, 182 products were available for these eighteen active ingredients, of
which 108 (59%) were affected by shortages (Table 2).
3.1   |   Utilisation Trends of Oral Antibiotics With
Shortages
3.1.1   |   Tetracyclines (J01A)
3.1.1.1   |   Doxycycline. There were fourteen products of doxycycline available during the study period. Five of these (36%)
were impacted by in total six shortages with a total duration
of 168 days. The Joinpoint analysis showed five segments. The
highest use of doxycycline was during winter months (months
6–9, 18–20) and the lowest in summer (months 1–3, 12–15)
(Table 2, Figure 1). The changes do not coincide with shortages,
and overall utilisation across 2022 and 2023 was similar.
3.1.1.2   |   Minocycline. There were two products of minocycline available during the study period. Both (100%) were
impacted by in total seven shortages with a total duration
of 470 days. The Joinpoint analysis showed four segments. Most
shortages of minocycline occurred in 2023 (months 13–24).
During months 1–9, minocycline utilisation increased significantly by 1% per month. From that point, utilisation remains
stable without significant changes despite three Joinpoints. The
lowest utilisation coincides with the period when both products
have shortages simultaneously (Table 2, Figure 1).
3.1.2   |   Beta-­Lactam Antibacterials, Penicillins (J01C)
3.1.2.1   |   Amoxicillin. There were 25 products of amoxicillin available during the study period. Eighteen of these
(72%) were impacted by 25 shortages with a total duration
of 3609 days. Most shortages occurred from halfway through
2022 until halfway through 2023, with some lasting for 2023
entirely. The Joinpoint analysis showed four segments following seasonal trends. In periods with the most shortages,
the seasonal decrease in use in Monthly Percent Change (MPC)
is steeper, while the seasonal increase is less steep compared
to periods without shortages. During months 1–6, the increase
in use is steeper (MPC 20%) than in months 12–18 (MPC 14%),
when most shortages occur. The decrease from months 7–12
is steeper (MPC-­14%) during shortages than in months 19–24
(MPC-­8%) when fewer shortages occur (Table 2, Figure 2).
3.1.2.2   |   Phenoxymethylpenicillin. There were nine
products of phenoxymethylpenicillin available during the study
period. Eight of these were impacted by in total fourteen shortages with a total duration of 1301 days. Most phenoxymethylpenicillin shortages occurred during the summer months at
the end of 2022 and the beginning of 2023. The Joinpoint analysis showed four segments following seasonal trends. In periods with most shortages, seasonal decrease in use is steeper
(MPC−10% vs.−6%) and seasonal increase is less steep (MPC
7% vs. 10%) compared to periods without shortages. Overall
use is similar from months 1–12 compared to 13–24 (Table 2,
Figure 2).
3.1.2.3   |   Flucloxacillin. There were eight products of flucloxacillin available during the study period. Four of these
(50%) were impacted by in total six shortages with a total duration of 1093 days. The Joinpoint analysis showed five segments.
The utilisation of flucloxacillin does not show changes coinciding with shortages. During shortages, increases and decreases
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Pharmacoepidemiology and Drug Safety, 2025
2
25
9
8
Minocycline
Amoxicillin
Phenoxymethyl-­
penicillin
Flucloxacillin
21
14
Doxycycline
Amoxicillin +
clavulanic acid
No of
products
Active
ingredient
12 (57%)
4 (50%)
8 (89%)
18 (72%)
2 (100%)
5 (36%)
No of
products
with
shortage (%)
17
6
14
25
7
6
Total
number of
shortages
3089
1093
1301
3609
470
168
Total
days of
shortages
TABLE 2    |    Shortages of antibiotics per active ingredient and Joinpoint analyses.
182 (118)
182 (187)
93 (73)
144 (149)
67 (39)
28 (23)
Mean
duration
in days
(SD)
1264–1618
986–2070
4935–
12 338
845–1224
5146–
8468
8.1*
−3.8*
11–14
14–19
19–24
14 [14–15]
19 [18–20]
3.9
−1.0
15–18
18–24
18 [14–22]
14.2*
−8.4*
13–19
19–24
19 [18–20]
7.0*
−6.1*
13–20
20–24
20 [18–21
−2.7*
1.2*
6–14
14–18
18–24
14 [13–15]
18 [17–20]
11.3*
−3.7*
14–18
18–24
18 [17–19]
−6.9*
7–14
14 [13–15]
10.7*
1–7
7 [6–8]
2.3*
−5.9*
3–6
6 [6–7]
5.3*
1–3
3 [3–3]
−9.6*
8–13
13 [12–14]
10.4*
1–8
8 [7–9]
−14.4*
7–13
13 [12–14]
20.3*
1–7
7 [6–8]
−4.4
9–15
15 [9–16]
1.4*
1–9
9 [4–10]
−10.5*
−0.9
7–11
11 [10–11]
8.7*
1–7
Monthly
Percent
Change
7 [6–8]
Usage
low-­high Joinpoints Segment
(DDD)
[95% CI]
months
144 (105–245) 3823–7130
64
(50–353.25)
72 (37–122.75)
92 (49–207)
61 (36–91)
18.5
(8.25–49.75)
Median
(IQR)
−7.2;-­1.6
5.9;18.5
−10.6;-­4.9
7.9;14.3
0.5;2.4
−4.3;-­1.3
1.8;3.1
−7.0;- ­4.0
2.6;8.0
−14.1;-­1.9
4.8;13.4
−16.9;-­5.8
8.1;13.1
−14.7;-­4.3
10.0;25.6
−19.3;-­10.5
15.8;25.1
−5.4;0.5
−4.9;630
−7.6;2.7
0.0;2.6
−5.8;-­2 .1
6.3;11.4
−12.2;-­7.2
−3.0;2.6
7.5;10.5
95% CI
(Continues)
0.002
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
0.006
0.001
0.001
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
0.121
0.115
0.092
0.049
0.002
0.004
0.005
0.467
< 0.001
P-­Value
5 of 13
No of
products
17
12
4
5
7
4
Active
ingredient
Cefalexin
Cefaclor
Trimethoprim
Trimethoprim +
sulfamethoxazole
Azithromycin
Erythromycin
TABLE 2    |    (Continued)
2 (50%)
2 (29%)
4 (80%)
4 (100%)
5 (42%)
12 (71%)
No of
products
with
shortage (%)
3
2
6
6
8
22
Total
number of
shortages
277
86
646
317
1630
3165
Total
days of
shortages
92 (49)
43 (23)
108 (60)
53 (28)
204 (104)
144 (162)
Mean
duration
in days
(SD)
98 (64–123,5)
43 (31,5-­54,5)
83
(60,25-­136,5)
70
(33,25-­71,5)
224
(165–265,5)
96,5
(21,5-­188,25)
Median
(IQR)
275–467
189–267
282–736
1141–1713
118–333
6184–8347
1.7
−7.0*
11–14
14–18
18–24
14 [14–15]
18 [17–20]
17.3*
1.4
13–17
17–24
17 [16–21]
3.3*
−2.3*
11–15
15–20
20–24
15 [14–16]
20 [19–22]
7.5*
−3.7*
11–14
14–18
18–24
14 [14–15]
18 [17–19]
−11.1*
0.7
6–11
11 [10–11]
10.3*
1–6
6 [4–7]
−4.6*
−0.5
7–11
11 [8–12]
5.5*
1–7
7 [3–8]
−22.2*
10–13
13 [13–14]
3.2*
1–10
1.2
14–24
10 [8–10]
−2.0*
3–14
14 [9–20]
7.6
1–3
3 [3–11]
−20.3*
2.7
6–11
11 [10–11]
22.4*
1–6
−0.1
14–24
6 [5–7]
−2.9
11–14
14 [7–22]
2.6
1–11
Monthly
Percent
Change
11 [3–12]
Usage
low-­high Joinpoints Segment
(DDD)
[95% CI]
months
−5.8;-­2 .1
4.5;12.5
−13.6;-­6.7
−1.5;4.0
8.1;14.3
−5.6;- ­0.6
1.9;6.3
−6.8;-­2 .7
−2.6;4.5
4.4;7.4
−6.6;4.5
9.3;28.4
−26.8;-­11.6
1.1;6.4
−0.1;3.1
−6.1;-­1.2
−0.7;15.5
−10.8;-­5.3
−1.8;7.6
−23.3;-­14.5
−0.8;7.0
18.8;27.8
−5.3;4.2
−5.0;6.5
−3.1;8.9
95% CI
(Continues)
0.003
< 0.05
< 0.05
0.414
< 0.001
0.008
0.005
0.016
0.748
0.001
0.588
0.014
0.013
0.001
0.056
0.040
0.094
< 0.001
0.308
0.001
0.092
< 0.001
0.9
0.4
0.2
P-­Value
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Pharmacoepidemiology and Drug Safety, 2025
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20
4
7
8
182
Clindamycin
Ciprofloxacin
Norfloxacin
Metronidazole
Nitrofurantoin
Total
108 (59%)
2 (25%)
4 (57%)
1 (25%)
6 (30%)
1 (17%)
8 (53%)
No of
products
with
shortage (%)
147
2
5
1
6
1
10
Total
number of
shortages
*Indicates a significant Monthly Percent Change, IQR = interquartile range.
15
No of
products
Roxithromycin
Active
ingredient
TABLE 2    |    (Continued)
17 768
81
432
42
640
63
659
Total
days of
shortages
41 (33)
86 (56)
91 (74)
73 (109)
Mean
duration
in days
(SD)
40,5
(24,75–56.75)
96 (25–146)
91 (41,5–103)
32 (24–46)
Median
(IQR)
286–674
285–1050
60–80
270–290
232–316
422–1323
21.7*
−6.3*
11–14
14–18
18–24
14 [14–15]
18 [17–20]
27.7*
1.5
8–11
11–24
11 [11–13]
14.9*
0.9
5–8
8–24
8 [7–18]
−11.4*
1–5
5 [3–6]
−27.1*
5–8
8 [8–8]
2.9
−1.6
12–24
1–5
0.8
1–12
−0.7*
3–24
5 [4–5]
12 [7–17]
8.6*
1–3
−0.3
14–24
3 [3–6]
−4.4
11–14
14 [9–21]
2.9*
1–11
11 [4–12]
−25.6*
−7.3
7–11
11 [9–11]
22.4*
1–7
Monthly
Percent
Change
7 [4–8]
Usage
low-­high Joinpoints Segment
(DDD)
[95% CI]
months
−1.7;1.8
−3.2;22.4
−26.7;-­3.6
−0.0;2.5
15.6;35.1
−31.8;-­19.1
−1.9;15.5
−3.1;-­0.9
−0.0;2.6
−1.0;-­0.5
1.8;14.1
−1.2;2.4
−6.0;4.3
1.3;4.0
−11.4;-­2 .3
11.8;35.1
−30.6;-­15.1
−14.7;11.3
17.7;30.5
95% CI
0.267
0.01
0.016
0.050
< 0.001
< 0.001
0.206
< 0.001
0.056
< 0.001
0.006
0.663
0.101
0.028
0.022
0.035
0.040
0.192
0.002
P-­Value
FIGURE 1    |    Number and duration of shortages and antibiotic utilisation between January 2022 (Month 1) and December 2023 (Month 24).
FIGURE 2    |    Number and duration of shortages and antibiotic utilisation between January 2022 (Month 1) and December 2023 (Month 24). A grey
bar indicates a product was not on the Australian market during that period.
in use occur, while overall use is similar from months 1–12
compared to 13–24 (Table 2, Figure 2).
3.1.2.4   |   Amoxicillin + Clavulanic Acid. There were
21 products available of amoxicillin + clavulanic acid. Twelve
of these (57%) were affected by in total seventeen shortages
with a total duration of 3089 days. Shortages of amoxicillin
+ clavulanic acid occurred mainly from months 6–24. The
Joinpoint analysis showed four segments following seasonal
trends. The increase in use from months 1–7 (MPC 11%) is
similar to the increase from months 14–18 (11%), despite shortages in the latter period. The month with the lowest usage
(month 2) does not coincide with the period of most shortages
(Table 2, Figure 2).
3.1.3   |   Other Beta-­Lactam Antibacterials (J01D)
3.1.3.1   |   Cefalexin. There were seventeen products of cefalexin available during the study period. Twelve of these (71%)
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FIGURE 3    |    Number and duration of shortages and antibiotic utilisation between January 2022 (Month 1) and December 2023 (Month 24). A grey
bar indicates a product was not on the Australian market during that period.
were impacted by in total 22 shortages with a total duration
of 3165 days. The Joinpoint analysis showed three segments
without significant changes. Overall use between months 1–12
and 13–24 is similar, shortages do not coincide with changes in
utilisation (Table 2, Figure 3).
3.1.3.2   |   Cefaclor. There were twelve products of cefaclor available during the study period. Five of these (42%) were
impacted by in total eight shortages with a total duration
of 1630 days. The Joinpoint analysis showed five segments. Most
shortages of cefaclor occurred during 2023 which coincides
with the period of lowest utilisation. The utilisation follows seasonal changes in 2022, with a 22% MPC increase in use from
months 1–6. The use of cefaclor remains stable until month
11, before it declines by −20% MPC until month 14. Utilisation remains low until month 18 and declines until month 24
(Table 2, Figure 3).
3.1.4   |   Sulfonamides and Trimethoprim (J01E)
3.1.4.1   |   Trimethoprim. There were four products of trimethoprim available during the study period. All four (100%)
were impacted by in total six shortages with a total duration
of 317 days. The Joinpoint analysis showed three segments.
There is an overlap in shortages; from months 12–15, two
of the three available products were in short supply. During this
period, utilisation is lowest. The fourth product was introduced
in month 17. Overall use from months 1–12 and 13–24 is similar
(Table 2, Figure 4).
3.1.4.2   |   Trimethoprim + Sulfamethoxazole. There were
five products of trimethoprim + sulfamethoxazole available
during the study period. Four of these (80%) were impacted by
in total six shortages with a total duration of 646 days. Joinpoint
analysis showed four segments. In 2022, all four trimethoprim
+ sulfamethoxazole products were affected by shortages; in
2023, a fifth product was introduced. There are two moments
at which two shortages occur simultaneously, months 7–9
and 12–15. Interestingly, utilisation increases with 3% MPC in
that first period, while in the second period, utilisation decreases
with −22% MPC. Before the shortages are resolved, utilisation
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increases again (17% MPC) until June 2023, after which it remains
stable (Table 2, Figure 4).
3.1.5   |   Macrolides, Lincosamides and Streptogramins
(J01F)
3.1.5.1   |   Azithromycin. There were seven products of azithromycin available during the study period. Two of these (29%)
were impacted by in total two shortages with a total duration
of 86 days. The Joinpoint analysis showed five segments. There
are no changes in utilisation coinciding with the shortages
(Table 2, Figure 5).
3.1.5.2   |   Erythromycin. There were four products of erythromycin available during the study period. Two of these (50%)
were impacted by in total three shortages with a total duration
of 277 days. The Joinpoint analysis showed five segments. During
two overlapping shortages from months 17–21, there is a shift in
utilisation from an 8% MPC increase to a − 4% decrease, whereas
utilisation in the same period in 2022 (months 6–11) is stable. The
increase in use from months 1–6 is slightly steeper (MPC 10%)
compared to months 14–18 (MPC 8%) (Table 2, Figure 5).
3.1.5.3   |   Roxithromycin. There were fifteen products
of roxithromycin available during the study period. Eight of these
(53%) were impacted by in total ten shortages with a total duration of 659 days. The Joinpoint analysis showed five segments.
From months 11–14, shortages of six products commenced
and five products were removed from the market. This coincided
with a − 26% MPC decline in use. Then, a 22% MPC increase was
seen until month 18, followed by a − 6% decrease until month 24.
The peak in utilisation in 2023 remains lower than in 2022. The
lowest use is similar in both years (Table 2, Figure 5).
3.1.5.4   |   Clindamycin. There were six products of clindamycin available during the study period. One of these (17%)
was impacted by one shortage of 63 days. The Joinpoint analysis showed three segments. The shortage coincided with a 3%
MPC increase in utilisation of clindamycin, which lasted from
months 1–11. From that point, there are no significant changes
in utilisation (Table 2, Figure 5).
Pharmacoepidemiology and Drug Safety, 2025
FIGURE 4    |    Number and duration of shortages and antibiotic utilisation between January 2022 (Month 1) and December 2023 (Month 24). A grey
bar indicates a product was not on the Australian market during that period.
FIGURE 5    |    Number and duration of shortages and antibiotic utilisation between January 2022 (Month 1) and December 2023 (Month 24). A grey
bar indicates a product was not on the Australian market during that period.
3.1.6   |   Quinolone Antibacterials (J01M) and Other
Antibacterials (J01X)
3.1.6.1   |   Ciprofloxacin. There were twenty products
of ciprofloxacin available during the study period. Six of these
(30%) were impacted by in total six shortages with a total duration of 640 days. The Joinpoint analysis showed two segments.
The first three shortages coincided with a 9% MPC increase in
use from months 1–3. This is followed by a − 1% decrease until
month 24, irrespective of shortages (Table 2, Figure 6).
3.1.6.2   |   Norfloxacin. There were four products of norfloxacin available during the study period. One of these (25%)
was impacted by a shortage of 42 days. The Joinpoint analysis
showed two segments. There were no changes in utilisation
during the shortage (Table 2, Figure 6).
3.1.6.3   |   Metronidazole. There were seven products of metronidazole available during the study period. Four of these (57%)
were impacted by in total five shortages with a total duration
of 432 days. The Joinpoint analysis showed four segments.
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FIGURE 6    |    Number and duration of shortages and antibiotic utilisation between January 2022 (Month 1) and December 2023 (Month 24). A grey
bar indicates a product was not on the Australian market during that period.
Metronidazole showed a sharp decrease in utilisation (−27%
MPC) from month 6–10, followed by a sharp increase (28% MPC)
until month 11. During this period, there was a shortage of two
products and a third was removed from the market. For the rest
of the study period, the use of metronidazole remained stable
(Table 2, Figure 6).
3.1.6.4   |   Nitrofurantoin. There were eight products
of nitrofurantoin available during the study period. Two
of these (25%) were impacted by in total two shortages with a
total duration of 81 days. The Joinpoint analysis showed three
segments. There were several changes to products available
on the market, with two products removed from the market
and another four products introduced during the study period.
The Joinpoint analysis showed a − 11% MPC decrease in use
during months 1–5 when the two shortages occurred. After
the shortages were resolved, utilisation increased with 15%
MPC until month 8 and remained stable afterwards (Table 2,
Figure 6).
4   |   Discussion
Antibiotic shortages were common in Australia during 2022 and
2023. Of the 21 oral antibiotics covered by the national reimbursement system, eighteen (86%) were affected by shortages.
For ten of those eighteen active ingredients (56%), shortages did
not coincide with a reduction in utilisation data. For the other
eight active ingredients (44%), there were declines in utilisation
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coinciding with one or multiple shortages. For cefaclor and roxithromycin, the impact of shortages is most clearly reflected by
decreases in utilisation (20% and 26% reductions, respectively).
For the other active ingredients, minocycline, amoxicillin,
phenoxymethylpenicillin, trimethoprim + sulfamethoxazole,
erythromycin and metronidazole shortages coincided with
minor changes in utilisation.
Shortages of antibiotics occurred often, as has been reported
earlier [1, 2, 5]. Most drug shortages are due to quality and manufacturing problems, although commercial factors and policy
also play a role [28]. This means that international geopolitical
factors and international trade greatly impact the occurrence
and impact of shortages. Although we acknowledge this as
an important aspect of the problem of antibiotic shortages, we
focus on factors specifically related to the shortages identified in
Australia during the study period.
Antibiotic shortages do not evidently affect the utilisation trends
of all antibiotics. Research in Canada also reported on the limited effect of medication shortages on purchasing data [29].
Nevertheless, shortages did seem to affect the utilisation of eight
active ingredients to a certain extent. This aligns with previous
research in the hospital setting that reported declines in antibiotic utilisation during shortages [8, 11]. Yet, there is no clear relationship between the absolute or relative number of shortages
and their duration and the impact on utilisation data. This implies that other factors also play a role in the impact of shortages
on drug utilisation.
Pharmacoepidemiology and Drug Safety, 2025
4.1   |   Factors That Influence the Impact
of Shortages
Various factors seem to influence the impact of shortages on
utilisation data. These may include the duration of the shortage, the number of products affected, and the availability of alternatives rather than just the proportion of available products
impacted. There does not seem to be a clear pattern in what percentage of products must be unavailable for it to be evident in
utilisation data or what number of alternative products ensures
no impact of shortages. For cefaclor, a shortage of approximately
45% of all products was reflected in a decline drug utilisation.
Nevertheless, similar proportions of shortages for other antibiotics were not as clearly reflected in utilisation. The results of this
study also do not clarify to what extent the duration of a shortage impacts drug utilisation. Shortages lasting more than half
a year seemed to impact roxithromycin and cefaclor. However,
shortages of penicillins for a similar duration were not reflected
similarly in utilisation. Earlier research has identified the availability of alternatives as an important element in the impact of
shortages [30]. However, the costs of shortages and the disease
treated by the drug in shortage were more often reported as important in this regard [31]. Finally, it seems that the impact of
shortages is also influenced by which specific products are unavailable when the shortages occur. The market share of a product may be an important factor for the impact a shortage of that
product has on national drug utilisation. This could explain why
one combination of shortages of trimethoprim + sulfamethoxazole resulted in a decline in usage, but another combination of
two shortages did not.
4.2   |   Factors That Mitigate the Impact
of Antibiotic Shortages on Utilisation
A factor potentially mitigating the negative impact of shortages
is the amount of antibiotic stock held in pharmacies, which may
attenuate or delay the impact of shortages to some extent. This
can be one explanation for utilisation patterns seen with minocycline. There were only two products of minocycline available
on the Australian market. Both products were affected by shortages at overlapping moments. While a reduction in utilisation is
seen, it does not reach zero at any point.
The resilience of healthcare professionals and the successful
implementation of national policy may also mitigate the impact
of shortages. In the hospital setting, guidelines and decision
support changes have been reported as useful in mitigating the
impact of shortages [11]. Australian pharmacists can switch between different products of the same active ingredient, which
seems a helpful solution for shortages when alternatives are
available. Additionally, pharmacists can be allowed through
temporary legislation to substitute different strengths or dose
forms without consultation with the prescriber [32]. It seems
that pharmacists manage to access such alternatives, either
through substitution or because general practitioners do not
prescribe antibiotics that are in shortage. Another Australian
mitigation strategy is the import of antibiotics from abroad,
which may be allowed in case of shortages [33]. As the number of available alternatives seems important for the impact of
shortages, this could be an important strategy to reduce the impact of shortages.
4.3   |   Strengths and Limitations
A strength of this study is that it provides a comprehensive overview of the impact of antibiotic shortages on national community antibiotic use. As such, it is important for the Australian
setting and shows how the impact of shortages can be explored
in other regions as well. Using national reimbursement data ensures the inclusion of most community antibiotic consumption.
Additionally, the mandatory reporting of shortages provides a
complete overview of all shortages impacting Australia.
The use of this data comes with several limitations. The time
between the date of dispensing to the patient and the date of processing the dispensing in the utilisation database varies. This
may lead to smaller seasonal fluctuations [21]. The influence of
the stock of antibiotics may further challenge the interpretation
of the impact of shortages, especially for those with a short duration. The reimbursement data does not include the utilisation
of imported antibiotics, which makes the utilisation data incomplete. Furthermore, it could be hypothesised that a shortage of
one active ingredient could increase the use of alternative active ingredients. However, Australia's therapeutic guidelines for
prescribing antibiotics for common conditions in primary care
include multiple alternatives per condition [34]. Therefore, the
data used in this study could not be used to investigate changes
in utilisation of alternatives to antibiotics in shortage. Also,
data on switching of antibiotics due to shortages could not be
examined in this data source, even though switching could be
an important strategy in mitigating the effects of shortages.
Finally, during the study period, there was a marked increase
in the Australian population (1.2 million, 4.7%) [25]. Although
the number of GPs in Australia has also grown during that period, the percentual growth was lower than that of the population (2.8%), further staining Australia's primary health care [35].
Reduced accessibility to GPs could result in a lower number of
antibiotic prescriptions unrelated to antibiotic shortages.
5   |   Conclusions
Shortages impact a large proportion of Australia's antibiotic
products. Nevertheless, the impact of these shortages on drug
utilisation seems limited for most active ingredients. Some active ingredients are utilised less during periods of shortages. The
absolute or relative number of shortages and their duration do
not show a clear relation with the impact on drug utilisation.
This implies that other factors also play a role.
Plain Language Summary
Medicine shortages are becoming an increasing problem worldwide. Antibiotics are some of the most used medicines, and
shortages have the potential to impact clinical practice and patient outcomes significantly. This research explored the impact
of antibiotic shortages on the utilisation of commonly used oral
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antibiotics in Australia. The most important findings from this
work were that there were a considerable number of antibiotic
shortages between 2022 and 2023, affecting most oral antibiotics. Some changes in national utilisation were seen for oral antibiotics coinciding with the periods of shortages. Still, despite the
frequency and extent of antibiotic shortages, there were no clear
or extensive changes in overall national patterns of use for most
antibiotics. The impact of antibiotic shortages on patients and
healthcare professionals seems complex and related to various
factors.
Conflicts of Interest
12. S. Khumra, A. A. Mahony, M. Devchand, et al., “Counting the Cost
of Critical Antibiotic Shortages,” Journal of Antimicrobial Chemotherapy 74, no. 1 (2019): 273–275, https://​doi.​org/​10.​1093/​jac/​dky410.
13. N. Miljković, B. Godman, E. van Overbeeke, et al., “Risks in Antibiotic Substitution Following Medicine Shortage: A Health-­Care Failure
Mode and Effect Analysis of Six European Hospitals,” Frontiers in Medicine 7 (2020): 157, https://​doi.​org/​10.​3389/​f med.​2 020.​0 0157​.
14. A. Acosta, E. P. Vanegas, J. Rovira, B. Godman, and T. Bochenek,
“Medicine Shortages: Gaps Between Countries and Global Perspectives,” Frontiers in Pharmacology 10 (2019): 10, https://​doi.​org/​10.​3389/​
fphar.​2 019.​0 0763​.
15. European Centre for Disease Prevention and Control, Antimicrobial
consumption in the EU/EEA (ESAC-­Net) -­Annual Epidemiological Report 2023 (Stockholm: ECDC, 2024).
The authors declare no conflicts of interest.
16. Centers for Disease Control and Prevention, “Antibiotic Prescribing
and Use: Outpatient Antibiotic Prescriptions -­United States 2022,” (2023).
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