UK LSE Pharma: U.S. Tariff Exposure & Share-Loss Risk

Executive Summary

Context

Effective Oct 1, 2025, a 100% U.S. import tariff on branded pharmaceutical products poses outsized risks to UK-based pharma/biotech companies. We analyzed key London-listed firms -- AstraZeneca (AZ), GSK, Hikma, Indivior, Dechra, etc. -- to identify those most exposed and the specific drugs likely to lose U.S. market share rapidly due to higher prices. We assessed U.S. revenue dependence, manufacturing footprints, drug competition, payer dynamics, exclusivity timelines, price elasticity, and mitigation options (e.g. shifting production onshore).

Findings

40-60%

AZ & GSK U.S. Revenue

Most exposed companies

100%

Import Tariff Rate

Effective Oct 1, 2025

0-6 mo

Share Loss Window

For high-risk drugs

AstraZeneca and GSK are most exposed -- both derive ~40–60% of revenue from the U.S.[1][2] and sell numerous U.S. products made abroad. Each has flagship drugs (e.g. Farxiga, Dovato) facing strong in-class competitors that could quickly capitalize on any tariff-induced price hikes.

Hikma and Dechra have moderate exposure: Hikma's ~60% North America revenue[3] includes imported generics and specialty drugs that could cede share to U.S.-produced alternatives, although Hikma is expanding U.S. manufacturing[4]. Dechra's ~40% U.S. revenue (FY2023: ~£331M) comes entirely from imported veterinary products -- niche markets but with potential substitution (e.g. compounding pharmacies) if prices double.

Indivior is least exposed: Despite ~80% of sales in the U.S., its key products (Sublocade, Perseris, Suboxone film) are already manufactured domestically via contract sites[5][6], insulating it from the tariff.

Drug-Level Risks

We identified high-risk tariff-exposed drugs whose U.S. sales could erode within months due to competitive dynamics (see Table B). Notably:

HIGH RISK Farxiga (AZ)

U.S. Sales:

$1.75B (2024)[7]

Elasticity:

High

Share Loss Window:

0-6 months

SGLT2 diabetes drug made ex-U.S.; closest rival Jardiance (Lilly/BI) can readily replace it on formularies. PBMs already pit these against each other for rebates[8], and a 100% tariff would likely push payers to Jardiance exclusively. Crowded class with generics expected ~2026–30[9]. Mitigation: AZ could tech-transfer Farxiga production to an existing U.S. site or CDMO (feasible ~12 months given small-molecule processes), but share loss in 0–6m is likely if onshoring lags.

HIGH RISK Dovato (GSK)

U.S. Sales:

~$1.5-1.8B (est.)[10]

Elasticity:

High

Share Loss Window:

0-6 months

~£2.24B global HIV sales (est. ~$1.5–1.8B U.S.), made in UK/EU. A 2-drug regimen (dolutegravir/3TC) facing Gilead's 3-drug Biktarvy (market leader). PBMs often manage HIV regimens aggressively (CVS's specialty formulary flags Dovato and Biktarvy for exclusion in some plans[11]), so any net price jump would spur switches. Minimal clinical difference for many patients, and no generics yet (dolutegravir patent ~2027). Mitigation: GSK has U.S. tablet manufacturing (e.g. Zebulon, NC)[12], so moderate difficulty -- they could potentially produce or package Dovato in the U.S. within ~6–12 months if capacity exists.

HIGH RISK Nucala (GSK)

U.S. Sales:

~$2.3B global[13]

Elasticity:

High

Share Loss Window:

0-6 months

IL-5 antibody for severe asthma, filled in Europe. Direct competitors Fasenra (AZ) and Cinqair (Teva) treat the same condition. Critically, AZ manufactures Fasenra's drug substance at its Frederick, MD site[14] (no tariff), whereas Nucala's is imported -- a tariff could make Nucala far costlier. Payers could prefer Fasenra (or Dupixent for overlapping eosinophilic asthma) if Nucala's cost doubles. In one 2025 PBM formulary update, Nucala and Fasenra are both listed among targeted asthma biologics[15], implying current parity; a tariff would break the tie. Class crowded, biologic biosimilars are on the horizon (patents into 2030s but a key GSK patent was invalidated in 2025[16]). Mitigation: Hard -- GSK lacks U.S. biologics plants for Nucala; tech transfer to a U.S. CMO (sterile biologic) could take ~18–24+ months. Share-loss window: 0–6m as payers rapidly shift new starts and re-authorizations to Fasenra/Dupixent.

MEDIUM RISK Zejula (GSK)

U.S. Sales:

£305M (~$0.39B)[17]

Elasticity:

Medium

Share Loss Window:

6-12 months

Niraparib PARP inhibitor for ovarian cancer, produced in Italy (Tesaro's supply chain). Closest substitute Lynparza (AZ/Merck's olaparib) is the class leader and could capture remaining Zejula patients if costs diverge. Both drugs lack generics until ~2028–30, but elasticity is medium: oncologists may stick with a familiar PARP if a patient is doing well. Still, payers could require use of Lynparza (Merck has substantial U.S. manufacturing) or even platinum chemo if Zejula's price spikes. Mitigation: Moderate -- GSK might use a U.S. solid-dose CMO; small-molecule tech transfer (~12 months). Revenue-at-risk: Medium (Zejula is <5% of GSK's U.S. sales, but important in Oncology portfolio).

HIGH RISK Vetoryl (Dechra)

U.S. Sales:

~$30-40M (est.)

Elasticity:

High

Share Loss Window:

0-6 months

Leading therapy for canine Cushing's disease (trilostane capsules; est. ~$30–40M U.S. sales). Manufactured in the UK, it would incur tariffs. While no FDA-approved generic exists, easy substitutes include compounding pharmacies that can legally prepare trilostane capsules from bulk API at much lower cost. If Vetoryl's price doubles, many cost-sensitive pet owners and vets would switch to compounded trilostane or older off-label drugs (e.g. mitotane). Veterinary market is price-sensitive and less brand-loyal. Mitigation: Moderate -- Dechra acquired a U.S. manufacturing site (Med-Pharmex, CA) in 2022 and could transfer Vetoryl production there in ~1 year if regulatory hurdles are cleared. However, any delay means share loss in <6m as veterinarians quickly adopt cheaper alternatives.

Outlook (Next 3–6 Months)

Key Expectations

📈 We expect AstraZeneca and GSK to pursue tariff-mitigation aggressively
🏭 Watch for announcements of manufacturing shifts to the U.S. -- e.g., AZ leveraging its planned $3.5B stateside investments[18], or GSK expanding contract production in the U.S.
💊 PBMs will be key players: monitor CVS, Express Scripts, and Optum formulary updates in Q4 2025–Q1 2026 for exclusion of tariff-burdened brands in favor of alternatives
⚠️ Top 5 at-risk drugs (Farxiga, Dovato, Nucala, Zejula, Vetoryl) are likely to see formulary downgrades or physician guidance changes quickly
🛡️ Companies might also seek tariff exemptions for critical drugs (e.g. no U.S. alternative for Shingrix; patient advocacy could be leveraged to exempt it)

If tariffs persist, by mid-2026 we anticipate market share realignment in diabetes, HIV, and respiratory biologics markets -- with U.S.-made competitors gaining ~10–20% share at the expense of tariff-hit brands.

Finally, patent cliffs loom for several of these products regardless of tariffs (e.g. Farxiga's next composition patent expires ~2026[9]). A tariff accelerates the inevitable by a few years, compressing the time window for monetization. Companies most exposed should accelerate contingency plans now, as detailed in the action list below.

Table A – Company-Level Tariff Exposure Overview

Company	U.S. Revenue % of Total	U.S. Mfg. Footprint? (Sites)	# of U.S.-sold Branded SKUs Made Outside U.S.	Overall Tariff Exposure
AstraZeneca	~43% (2024)[1]	Yes: Biologics in MD (Frederick); some small-molecule production planned (VA/MA)[19]. Major U.S. presence but many drugs still imported.	10+ (e.g. Farxiga tablets -- made ex-U.S.; Symbicort inhaler -- UK/SE; Tagrisso -- likely UK; Zoladex -- UK; etc.)	High. Heavy U.S. dependence and multiple imports. Key franchises (diabetes, oncology) at risk; mitigation in progress but <50% of portfolio onshore.
GSK	~44% (2024)[2] (was 55% in 2023)	Yes: Tablets & inhalers in NC (Zebulon)[12]; legacy biologics in MD (Rockville -- e.g. Benlysta)[14]. Some vaccine antigen in MT.	10+ (e.g. Shingrix -- finished in Belgium[20]; Dovato/HIV pills -- made in UK/EU; Nucala -- EU fill; Ellipta inhalers -- UK[21]; Zejula -- Italy; etc.)	High. Many imports (including vaccines). U.S. plants exist (could localize some oral drugs quickly), but big products (biologics, vax) remain offshore. High U.S. revenue reliance amplifies impact.
Hikma	~61% (NA 2023)[3] (mostly U.S.)	Yes: Broad U.S. generics manufacturing (Columbus, OH for orals/nasal; Cherry Hill, NJ for injectables)[22][23]. Investing $1B to expand by 2030[4].	~5+ (e.g. Ryaltris nasal spray -- made in India; generic Advair Diskus -- device supplied via UK partner[24]; certain injectables from EU facilities). Many other generics produced in U.S. already.	Medium. U.S. sales are critical, but in-house U.S. production covers many products (limiting tariff hits). Some specialized imports could lose share to U.S.-made generics. Ongoing expansion lowers future risk[4].
Indivior	~83% (2023)[25]	Limited (until 2024): No large U.S. plant historically. But acquired a Raleigh, NC injectable plant in 2023[26][27]; HQ in VA. Relied on U.S. contract manufacturers (Curia, Patheon) for production[5][28].	~0. All major U.S. products are made in the U.S.: Suboxone Film (film tech by Aquestive NJ)[6]; Sublocade LAI (filled by Curia in Albany, NY)[5]; Perseris LAI (made by Patheon in NC & Curia MA)[29]	Low. Despite U.S.-centric sales, Indivior's supply chain is U.S.-based, shielding it. (Tariffs could raise raw material costs marginally, but no finished-dose imports.)
Dechra	~40% (est. NA FY2023 ~£331M of £762M)[30]	Yes (recent): Small U.S. manufacturing via Med-Pharmex, CA (acquired 2022, does sterile & tablets for vet meds). Most legacy production in UK/EU (Skipton UK, Zagreb HR, etc.)[31].	~5+ (e.g. Vetoryl capsules -- UK; Zycortal injection -- EU; Phenobarbital tabs -- UK). U.S. plant not yet producing these main products (focus of integration post-2022).	Medium. High share of products imported, but veterinary market dynamics differ (somewhat lower political scrutiny, though buyers can substitute via compounding). Recent U.S. plant gives a path to onshore key products within ~1 year if prioritized.

Sources: Company annual reports and results for U.S. sales[1][2][3]; manufacturing site disclosures[12][14][23]; news on expansions[18][4]; product regulatory filings for manufacturing location[20].

Note: "SKUs made outside U.S." counts distinct branded products (not dosage strengths) with finished dose imported. Overall Exposure qualitatively weighs U.S. reliance, number/value of at-risk drugs, and ability to mitigate (existing U.S. capacity vs. need for new).

Table B – Drug-Level Tariff Share-Loss Risk Analysis

Tariff-Exposed Drugs (Selected): Likely to lose U.S. market share rapidly if 100% import tariffs raise their cost.

Company (Mfr.)	Drug (Brand & INN)	Indication(s)	U.S. Sales (latest FY)	Finished Dose Mfg. Country (API Source)	Patent/Exclusivity Status (U.S.)	Key Competitors / Substitutes (U.S.)	PBM Formulary Status (CVS/ESI/Optum)	Biosim/Generic Timeline	Tariff Exposure? (Why)	Price Elasticity (Competitive Intensity)	Projected Share-Loss Window (post-tariff)	Revenue-at-Risk (Qualitative)
AstraZeneca (UK)	Farxiga (dapagliflozin)	Type-2 diabetes; Heart failure, CKD adjunct	$1.75 B (2024 US)[7]	UK / EU (API from UK/JP; co-developed by BMS/AZ)	Composition patent ~2026; FDA Orange Book lists patents to 2035[9]. No generics yet (possible 2030 entry[32]).	Jardiance (empagliflozin, Lilly/BI) -- equal class efficacy; Steglatro (Merck) -- minimal share.	Formulary: PBMs leverage class competition. ESI 2024: listed Farxiga & Jardiance as excluded (plan-dependent)[8]. Payers often prefer one SGLT2 (high rebating).	No generics until ~2030[32]. (Jardiance LOE similar ~2029).	Yes. Final tablets imported (no large-scale US production known). Tariff would double cost.	High. SGLT2 market is crowded and price-sensitive[8]. Little patient differentiation; PBMs can easily switch coverage to Jardiance (U.S. supply) if Farxiga's net price rises.	0–6 mo. Rapid. Next formulary cycle, expect Farxiga dropped entirely in favor of Jardiance; physicians can substitute immediately for new Rx.	High. Farxiga = ~7% of AZ's US sales[1]. Loss of preferred status could cut sales sharply. (However, AZ retains some HF/CKD niche uses).
GSK (UK)	Dovato (dolutegravir/lamivudine)	HIV-1 infection (single-tablet regimen)	~£2.24 B global 2024[10] (est. ~$1.5–1.8 B US)	UK or EU (bulk by ViiV/GSK in UK; formulation likely in EU)	Dolutegravir comp. patent ~2027; lamivudine generic. No generic combo until at least 2028. Authorized generics: none.	Biktarvy (bictegravir/F/TAF, Gilead) -- #1 HIV regimen; Triumeq (GSK's older 3-drug) -- some remaining use; 2-pill generic options (less favored).	Formulary: CVS Advanced Specialty list flags Dovato & Biktarvy (and others) for exclusion in some plans[33] -- some insurers cover only older generic regimens to cut costs. Generally, one of Biktarvy vs Dovato may be "preferred" with better co-pay.	No generics before 2028–30 (ViiV settled some challenges aligning with patent expiry). Long-acting injectables (Cabenuva) emerging but niche.	Yes. All Dovato tablets sold in US are imported from GSK/ViiV EU supply chain (no evidence of Zebulon production). Tariff would apply 100%.	High. Very competitive market. Little clinical difference for suppressed patients; payers easily switch to alternative regimens. Gilead can absorb switches via Biktarvy (U.S.-made or not tariffed), especially if Dovato cost rises.	0–6 mo. Fast. Within months, PBMs could make Dovato non-preferred or require step-through Biktarvy. New patients almost entirely shifted by next policy update.	High. HIV franchise is ~14% of GSK's US revenue[34]. Dovato is the top seller (42% of GSK's HIV sales)[35]. A formulary exclusion would materially hit GSK's U.S. growth[36].
GSK (UK)	Nucala (mepolizumab)	Severe eosinophilic asthma; EGPA	~$2.3 B global (2024)[13] (est. ~$1.0–1.2 B US)	EU (UK/BE) -- Fill-finish in EU[37]; API from cell culture in UK. No U.S. production.	Biologic approved 2015; key patents into 2030s. Patent update: GSK's IL-5 patent invalidated (2025)[16] -- biosimilar entry could be as early as ~2027 pending appeal[16]. No biosimilars on market yet.	Fasenra (benralizumab, AZ) -- same class IL-5 inhibitor; Dupixent (Sanofi/Regeneron) -- different IL-4/13 drug, but overlaps in eosinophilic asthma use; Cinqair (reslizumab, Teva) -- IL-5 IV, less used.	Formulary: Typically one preferred asthma biologic. ESI 2025 NPF Exclusions: lists Dupixent, Fasenra, Nucala, Tezspire, Xolair all as negotiable class options[15]. Many plans prefer Dupixent for broad type 2 asthma, and either Nucala or Fasenra (but not both). A cost spike would push payers to favor Fasenra.	No biosimilars until ~2027+ (pending patent outcomes). Competition currently is brands jockeying for formulary tier.	Yes. Fully imported (no U.S. assembly). Tariff doubles cost to U.S. buyers.	High. Payers have leverage: at least 3 alternative biologics for similar patients. Not all are identical in mechanism, but cost-sensitive insurers could restrict Nucala in favor of Fasenra (which is made in USA[14]) or Dupixent. Clinics can switch stable patients if required by insurance.	0–6 mo. Rapid for new starts (plans stop covering Nucala immediately for naïve patients). Existing patients might be forced to switch at policy renewal (~6–12m). Expect significant share shift within 2 quarters post-tariff, absent manufacturer rebates eating the cost.	Medium. Nucala ~6% of GSK sales[13]. Loss of share to Fasenra/Dupixent could cut U.S. Nucala revenue by a third or more. GSK's hit is cushioned by global sales and lack of generic -- but U.S. growth would stall.
GSK (UK)	Zejula (niraparib)	Ovarian cancer (maintenance PARP inhibitor)	£305 M US (2024)[17] (~$0.39 B)	Italy (former Tesaro plant or CMO in EU for capsules); API from EU. No U.S. plant.	Approved 2017. U.S. patents until 2030 (estimated). Settlement with generics likely allows entry by Jan 2030[32]. First PARP (Lynparza) LOE ~2028.	Lynparza (olaparib, AZ/Merck) -- dominant PARP, multiple indications; Rubraca (rucaparib) -- withdrawn in U.S. (2023 bankruptcy), minimal factor; New class: Avastin combos or checkpoint inhibitors in some ovarian cases (not direct substitutes but alternatives if PARPs too costly).	Formulary: Oncology drugs typically covered under medical benefit with PA. No PBM exclusion noted for PARPs (clinical category small). Medicare Part B spends heavily on Lynparza; parity coverage for PARPs. Payers could institute PA requiring Lynparza first if cost diverges.	Lynparza generics expected ~2028; Niraparib ~2030. No biosimilars (small molecule). So until then, brand vs brand competition.	Yes. Imported (no U.S. packaging known). Subject to tariff at U.S. customs.	Medium. Oncology has some stickiness -- physicians may be hesitant to swap a patient's maintenance therapy. However, new patients could easily start on Lynparza if Zejula's price doubles. Merck (Lynparza) could also offer aggressive discounts to payers. Class is less crowded (essentially 2 players now), so elasticity is moderate.	6–12 mo. Moderate pace. Over 6–12 months, expect Zejula share erosion as oncologists and payers favor Lynparza to save cost. Existing Zejula patients might remain until progression due to clinical inertia, but new patient share could drop swiftly in <1 year.	Low–Medium. Zejula is <5% of GSK's U.S. revenue. Revenue-at-risk is modest in absolute terms. However, losing U.S. market momentum could hurt GSK's oncology strategy; and patients switching off now may not return even post-tariff.
Dechra (UK)	Vetoryl (trilostane)	Canine Cushing's disease (hyperadrenocorticism)	Est. ~$30–40 M (U.S. FY2023). Dechra does not disclose by product; NA segment £168.8M, Vetoryl among top sellers.	UK (capsule manufacturing in Skipton, UK). API from third-party (trilostane off-patent). No U.S. production yet.	Launched 2008 (first FDA-approved for canine Cushing's). No patent or exclusivity remaining. Open to competition, but no generic approved -- likely due to cost of full FDA vet drug approval.	Compounded trilostane -- U.S. compounding pharmacies legally fill Rx with bulk API (much cheaper per dose, albeit unapproved); Lysodren (mitotane, human chemo) -- an older therapy for Cushing's in dogs, generic tablets available (off-label use by vets).	Formulary: N/A in human PBMs. Sold via vet distributors. Price-sensitive market -- pet owners often compare pharmacy prices. Some pet insurance covers Vetoryl; if price doubles, insurers may require trying compounded drug.	No generic Vetoryl (FDA vet generic pathway unutilized likely due to compounding alternative). Compounding provides "de facto generics." Bulk trilostane API (often from China/India) might be tariffed as raw chemical at lower rate, but compounding could avoid finished drug tariff.	Yes. All Vetoryl capsules for U.S. are imported from the UK (tariff applies). Dechra's new US plant (Med-Pharmex) isn't yet making Vetoryl.	High. Extremely price elastic. If Vetoryl price doubles, many veterinarians will shift to compounded trilostane which can cost 50–80% less per dose (no costly regulatory approval) -- a common practice even now for cost or dosing flexibility. Dechra has limited ability to offer rebates in this cash-pay market.	0–6 mo. Very fast. Vet clinics and pet owners will react immediately to price hikes. Within 6 months of tariff, Vetoryl's volume could drop significantly as vets either script out to compounders or use alternatives.	Medium. U.S. Vetoryl might be ~10% of Dechra's revenue. Losing half of that to compounders is a hit but not existential. However, margins on Vetoryl are high; revenue loss would disproportionately affect profit. Also, once vets switch to compounded drugs, Dechra may struggle to win back that business even if tariffs lift.

Sources: Sales data from company disclosures (Farxiga[7]; Dovato[10]; Nucala[13]; Zejula[17]; Vetoryl from segment info). Manufacturing sites from regulatory filings (e.g. Shingrix: Belgium[20]; Fasenra: AZ Frederick, MD[14]) and company reports. Patent/exclusivity from FDA Orange Book, recent patent litigation news (e.g. Nucala patent loss[16]). Formulary status from PBM exclusion lists[8][33] and specialty drug lists[15].

Note: Tariff Exposure = Yes for drugs with finished-dose import. Even if API is foreign, a drug made into final form in U.S. would not incur the tariff on sale (though COGS may rise). Price Elasticity scores consider availability of therapeutically similar alternatives and payer willingness to substitute. Projected Share-Loss Window assumes tariffs effective Oct 2025 and sustained; "0–6m" implies notable share shift by Q2 2026.

Top 5 At-Risk Drugs – Rationale & Mitigation

#1 Farxiga (AZ)

CRITICAL RISK

Size of Exposure

Farxiga's $1.75B U.S. sales[7] could decline sharply, affecting ~7% of AZ's global revenue.

Why Rapid Share Loss

Tariff would make Farxiga (already second-line to Jardiance for many payers) uncompetitive overnight. With U.S. diabetes guidelines agnostic between SGLT2s, insurers can simply prefer Jardiance exclusively.

Mitigation Strategy

AstraZeneca can attempt to onshore production -- possibly via its Ohio or future Virginia facility (small-molecule manufacturing can be set up in ~9–12 months). In interim, AZ might provide rebates to offset the tariff (effectively eating the 100% cost increase) to avoid losing formulary status. This, however, crushes margin and may not be sustainable. A long-shot mitigation is seeking a tariff exception on grounds of no immediate U.S. supply alternative -- politically uncertain.

#2 Dovato (GSK)

HIGH RISK

Exposure Size

High -- Dovato is core to GSK/ViiV's HIV growth (27% YoY in 2024)[10].

Why Likely to Lose Share Quickly

As the leading HIV regimen for GSK, a tariff would double its price to payers, who could then favor Gilead's regimen. PBMs have shown they're willing to exclude even unique drugs if a competitor offers a better net deal[33]. Dovato's advantage (2 drugs vs 3) likely won't overcome a huge price gap.

Mitigation Strategy

GSK could fast-track U.S. production at its Zebulon, NC site. Dolutegravir and lamivudine are well-known, so tech transfer could complete by late 2026. GSK might also negotiate with U.S. government since HIV drugs are essential -- possibly securing a tariff waiver or using government channels (e.g. PEPFAR programs) to keep supply flowing. Until then, expect ViiV to heavily discount Dovato (or bundle with other drugs) so payers keep it accessible -- a stopgap that erodes profit.

#3 Nucala (GSK)

HIGH RISK

Exposure

~12% of GSK's specialty med sales[13]; losing share impacts a significant revenue stream (~$1B).

Why Formulary Exclusion Likely

This biologic would likely see formulary exclusion in favor of Fasenra or Dupixent if its cost doubled.

Mitigation Strategy

Very challenging. GSK lacks a quick onshore manufacturing solution for Nucala -- building new biologics capacity or qualifying a U.S. CMO could take 2+ years. One option: contract existing U.S. biologics players (e.g. ThermoFisher, Samsung Bio in the U.S.) to fill-finish Nucala; however, even tech transfer for biologics is ~18 months. GSK may also push its new oral IL-5 inhibitor (if any in pipeline) as a long-term replacement not needing import. Short-term, GSK likely increases physician and patient support programs to keep Nucala on tier (effectively partially offsetting tariff via rebates or co-pay assistance). Given the newly expanded COPD indication (2025)[38], GSK might argue Nucala's importance to secure an exemption or at least buy time under medical necessity grounds.

#4 Zejula (GSK)

MODERATE RISK

Exposure

Moderate for GSK; however, the ovarian PARP market itself is important for future pipeline combinations.

Market Position

While not as large as others, Zejula's position could swiftly weaken as oncologists default to Lynparza (especially since Merck/AZ could drop Lynparza's price or offer deals to payers).

Mitigation Strategy

GSK can cope by focusing ex-U.S. (the tariff doesn't hit EU sales) and accelerating its next-gen agents (e.g. combo trials with Jemperli[39]). To maintain U.S. presence, GSK might partner with Merck to ensure at least one PARP is available cheaply (since Merck co-markets Lynparza, they have interest in not letting tariffs distort the market -- perhaps a joint effort to lobby against it for oncology drugs). Technically, GSK could move some Zejula production to the U.S. via a CMO in 12–15 months; but the urgency is slightly lower given the niche status and slower share erosion (clinically, some patients on niraparib will stay on it). GSK's bigger concern is upcoming biosimilar competition in 2028–30 regardless -- the tariff just foreshadows that loss.

#5 Vetoryl (Dechra)

HIGH RISK - VETERINARY

Unique Challenge

This stands out because of immediate substitutability via compounding. We anticipate many vet clinics will drop Vetoryl if prices jump, harming Dechra's U.S. earnings.

Exposure

Vetoryl is one of Dechra's top products; loss of U.S. sales (which are ~40% of Vetoryl's global volume) would hurt growth and margin significantly.

Mitigation Strategy

Dechra can leverage its Med-Pharmex plant in California -- possibly start U.S. production of Vetoryl by mid-2026 to avoid tariffs. Regulatory hurdles are lower for transferring a veterinary product compared to human (no FDA pre-approval required for site transfer in animal drugs, just filing). In the interim, Dechra might lower U.S. prices or offer rebates to large vet hospital chains to blunt the tariff impact and dissuade compounding. However, competing with compounders on price is tough. Another angle: Dechra could push state pharmacy boards or the FDA to enforce restrictions on compounding (since an approved product exists) -- but if Vetoryl's price doubles by policy, regulators may be lenient with compounding as a "public interest" alternative. Thus, Dechra's best move is a quick tech transfer to the US and possibly absorbing tariff costs short-term to keep customers.

Ranked Exposure Lists

Most Exposed Companies

(blend of U.S. dependence, tariff-affected portfolio, mitigation difficulty)

1. AstraZeneca – HIGH

~43% U.S. sales[1]; multiple blockbuster imports (Farxiga, Tagrisso, Symbicort) with readily available competitors. Mitigation: moderate (has some U.S. facilities, ramping up).

HIGH

2. GSK – HIGH

~44% U.S. sales[2]; big products made abroad (vaccines, HIV drugs, biologics). Mitigation: mixed (tablets easier to shift than vaccines/biologics). High absolute revenue at risk, though some products (e.g. Shingrix) have no substitute (risk to volume is lower, but huge profit hit if GSK eats tariff).

HIGH

3. Hikma – MEDIUM-HIGH

60% U.S. sales[3], but many generics already U.S.-made. Still, some imports (specialty generics like inhalers, nasal sprays) could lose share. Mitigation: good (strong U.S. manufacturing base expanding[4]). Impact mostly on specific products rather than whole portfolio.

MED-HIGH

4. Dechra – MEDIUM

~40% U.S. sales, all imported. Niche markets but highly elastic demand (vet substitutes). Mitigation: moderate (one U.S. site acquired, needs integration). Being acquired by EQT (2023) may bring capital to onshore production.

MEDIUM

5. Indivior – LOW

~83% U.S. sales[25] but essentially fully onshore supply chain. Little direct tariff impact unless policy extends to APIs (Indivior does import some raw buprenorphine from UK[40]). Mitigation already in place (Raleigh plant to secure U.S. supply[26]).

LOW

Drugs Likely to Lose U.S. Share Fast

(within 6–12 months of tariff)

1. Farxiga (AZ)

SGLT2 class switch to Jardiance – likely formulary drop; high-volume primary care drug.

0-6 mo

2. Dovato (GSK)

HIV regimen replaced by competitor (Biktarvy) on payer preference; significant patient base affected quickly.

0-6 mo

3. Nucala (GSK)

Asthma biologic steered out by payers in favor of Fasenra/Dupixent; clinics have alternatives ready.

0-6 mo

4. Vetoryl (Dechra)

Veterinary med supplanted by compounding pharmacies almost immediately due to cost-sensitive pet owners.

0-6 mo

5. Zejula (GSK)

Oncology maintenance therapy gradually abandoned in favor of Lynparza (slightly slower than others due to patient management).

6-12 mo

Honorable Mentions:

Symbicort (AZ) – brand already declining due to generics, a tariff would push any remaining users to authorized or generic versions (which may also be imported, so a complex case where all competitors face tariffs – less clear share shift, more an overall cost increase).

Imfinzi (AZ) – in stage III lung cancer, could lose out to non-tariffed Keytruda off-label in some cases, but given distinct indications, the shift might be limited.

Cabenuva (ViiV/GSK) – long-acting HIV injection (made in UK/Canada); a tariff doubling its price would severely limit adoption in favor of daily oral therapy, though not a "share shift" to a competitor per se, more a reversion to older standard of care.

Action Plan & Monitoring

Monitor Onshoring Announcements

Track press releases and earnings calls for manufacturing re-shoring. In the next 3–6 months, we expect statements from AstraZeneca and GSK about increasing U.S. production (e.g. "AZ to produce XX drug at its Wilmington or new VA site by H2 2026" or "GSK partnering with ThermoFisher for U.S. fill-finish of Nucala"). If such announcements are absent by Q2 2026, risk is even higher – it means companies might be choosing to absorb tariffs or lose share rather than invest, signaling potential earnings hits.

PBM Formulary Updates (Q4'25 and Jan'26)

Watch CVS Caremark's January 2026 formulary exclusion list, Express Scripts' NPF updates, and OptumRx changes. Red flags: Farxiga, Dovato, Nucala (etc.) moved to excluded or higher tier status. CVS's Advanced Control Specialty Formulary in late 2025 should indicate if Dovato or Nucala are dropped[33]. Express Scripts mid-2025 update will show if Farxiga is no longer covered[8]. These will foreshadow sales declines.

Company Guidance & Disclosure

In the next earnings, see if companies quantify tariff impact or volume shifts. If GSK, for example, lowers 2026 U.S. sales guidance for HIV or asthma franchises, that confirms share-loss. AstraZeneca might cite "adverse U.S. pricing in diabetes" – an indirect way to describe tariff costs or share loss. Also look for "revenue at risk" comments or contingency plans (e.g. "exploring tariff exemptions for critical medicines").

Regulatory and Political Developments

Any indication of tariff exemptions for medicines (Congress pressure, FDA input) is crucial. Pharma lobbying may succeed in carving out certain life-saving drugs. If, say, shingles vaccine or cancer drugs get exempted, adjust exposure assessments (GSK's Shingrix risk would drop). Track USTR statements or amendments to the tariff policy for flexibility.

Competitor Actions

Conversely, monitor U.S. competitors' moves: e.g. Lilly might ramp up Jardiance supply or offer discounts expecting Farxiga's trouble. Merck may boost Keytruda supply in indications where UK imports (e.g. Jemperli) falter. These will manifest in competitor earnings (watch for unusual sales jumps in Jardiance, Fasenra, etc., which correspond to drops in the UK companies' products).

Inventory and Distribution Adjustments

There could be pre-tariff stockpiling. The affected companies might ship extra inventory into the U.S. before Oct 1, 2025. For instance, if GSK floods wholesalers with six months of Dovato supply in Q3 2025 (to beat the tariff), we'd see a transient sales spike[34] followed by a dip. Keep an eye on U.S. channel inventory comments (GSK already noted inventory impacts for Nucala/Benlysta in late 2024[41]). This could buffer the initial share loss but only delays the impact to when inventory is depleted.

In Summary

UK pharma firms need to act swiftly to maintain U.S. market positions – by localizing production where feasible, negotiating with payers, and lobbying for relief. The tariff accelerates competitive battles that were on the horizon (e.g. patent expiries, biosimilars) into an immediate issue. Stakeholders should prepare for heightened volatility in U.S. sales for these companies in 2025–2026. We will continue updating our analysis as new data emerges on manufacturing shifts or policy changes.

Next 3–6 Month Catalysts to Watch

Q1 2026: AstraZeneca Investor Day

Are there announcements of U.S. manufacturing for Farxiga or a strategy to handle tariffs?

Feb 2026: GSK Q4 2025 Results

Look for revisions in HIV or respiratory guidance; any mention of "successful tariff mitigation by producing X in Maryland" or, conversely, admission of U.S. market share pressure.

Late 2025: PBM 2026 Formularies

Particularly Express Scripts: if Farxiga or Nucala are explicitly dropped, it confirms our worst-case scenario for those drugs[8].

Ongoing: FDA Generic/Biosimilar Approvals

An early generic Farxiga or biosimilar Nucala approval (if any) would compound tariff issues – effectively a one-two punch on pricing and competition.

2026: Onshoring Progress Updates

Indivior's Raleigh plant coming online (should be operational by 2026)[26] – a positive example; will others follow? Any delays or issues (e.g. regulatory hurdles transferring Vetoryl to Med-Pharmex) could prolong exposure for those companies.

By tracking these factors, we will gauge whether the identified companies can navigate the tariff storm or if U.S. market share will markedly realign in the coming year.