Sun Assam Halt Exposes Pseudomonas Risk With No Clean Restart Precedent

Sun Pharma Halts Eye-Care Drug Production Amid Quality Concerns

Sun Pharmaceutical Industries has ceased manufacturing eye-care drugs at its plant in Assam, India, following significant quality concerns. The company stated it "voluntarily recalled" 11 ophthalmology products and "voluntarily initiated a temporary cessation" of manufacturing. However, reports indicate Indian drug regulators ordered the halt on August 20 after identifying quality management system failures during a joint inspection. This action follows a July recall of 11 ophthalmic products from the Indian market, which later emerged to be linked to bacterial contamination, specifically Pseudomonas, found in batches of Predmet eye drops. This pathogen was also responsible for a U.S. eye infection outbreak in 2022-2023. Sun Pharma has submitted a compliance report to regulators and is taking remedial actions.

• Sun Pharma's announcement of a "voluntary recall" of 11 ophthalmology products and a "voluntary cessation" of manufacturing at its Assam plant contrasts with reports that Indian drug regulators formally ordered the halt on August 20. This order stemmed from a joint federal-state inspection that uncovered critical failures within the company's quality management system, prompting Sun Pharma to submit a compliance report for review.
• The manufacturing cessation and recall are directly linked to serious quality concerns, including bacterial contamination. Specifically, batches of Sun Pharma's Predmet eye drops were found to be contaminated with Pseudomonas, a pathogen known to cause severe eye infections. This contamination issue mirrors a U.S. eye infection outbreak in 2022-2023, which was associated with artificial tears manufactured by another Indian drugmaker.
• The news of the manufacturing shutdown emerged concurrently with Sun Pharma's announcement of FDA approval for Ilumya in adults with active psoriatic arthritis, an expansion of its 2018 plaque psoriasis label. Despite this regulatory win, the company reported a slowdown in Ilumya's U.S. business in the most recent quarter, indicating a mixed operational landscape for Sun Pharma.

Manufacturing Quality: A Critical Challenge in Ophthalmic Treatment

Current treatment of ophthalmic infections remains constrained by poor drug delivery to ocular tissues and the growing complexity of pathogen resistance. Delayed and difficult diagnosis further limits timely therapeutic decisions and increases risk of sight-threatening outcomes.

• Suboptimal bioavailability and systemic toxicity: Sub-optimal physicochemical properties prevent Ganciclovir (GCV) from reaching therapeutic concentrations in back of the eye (retina) tissue after oral and intravenous administration, while chronic high dose administration results in systemic toxicity. Eye drops containing antibacterial, antifungal, or antiviral agents such as besiloxacin, moxifloxacin, ofloxacin, voriconazol, econazole, fluconazole, and acyclovir need to be applied frequently due to their low bioavailability, and early generation herpes simplex virus drugs had low bioavailability and measurable local cellular toxicity due to their nonselective mode of action.

• Risks and limitations of local administration: Local intravitreal injections suffer from poor ocular bioavailability and require repeated administration which can cause retinal detachment, retinal/vitreal hemorrhage and endophthalmitis. In silicone oil (SO)-filled eyes, clinical evidence is mainly from case reports and small series, with limited literature to guide pharmacokinetics, safety, and optimal dosages.

• Antimicrobial resistance and multidrug-resistant strains: Resistance in Staphylococcus aureus (S. aureus), Streptococcus pneumoniae (S. pneumoniae), Pseudomonas aeruginosa (P. aeruginosa), and coagulase-negative staphylococci (CoNS) emerge through genetic mutations, horizontal gene transfer, and biochemical mechanisms such as enzymatic degradation, target modification, efflux pumps, and reduced membrane permeability. The rise in multidrug-resistant strains, particularly methicillin-resistant S. aureus, fluoroquinolone-resistant P. aeruginosa, and drug-resistant S. pneumoniae has been linked to delayed treatment response, increased healthcare costs, and sight-threatening outcomes, with an increase in resistance to fourth-generation fluoroquinolones detected for both MRSA and MSSA over the study period.

• Drivers of resistance and ocular-specific susceptibility challenges: Key drivers include inappropriate or prolonged topical antibiotic use, routine prophylaxis in ocular surgery, subtherapeutic dosing, and cross-resistance with systemic antimicrobials, while recent topical antimicrobial exposure is a predictor of reduced culture positivity and elevated resistance rates in subsequent ocular isolates. Interpreting antimicrobial susceptibility testing (AST) remains challenging because clinical breakpoints are generally derived from systemic dosing regimens despite substantially higher, albeit transient, drug concentrations at the ocular surface, and the ocular surface microenvironment including tear proteins, inflammation, biofilm formation, and concurrent serum therapy may influence activity, with biofilm formation further complicating eradication.

• Delayed, insensitive, and limited diagnostics: Delayed diagnosis of Acanthamoeba and fungal keratitis is typical, resulting in significant vision loss, partially due to low sensitivity and time delay of corneal cultures. In Acanthamoeba keratitis the mean duration of symptoms at presentation was 21 days and mean duration from presentation to definitive diagnosis was 14 days, with delayed diagnosis associated with worse outcomes and need for surgical intervention, while Exophiala endophthalmitis of exogenous origin is characterized by diagnostic delays, limited therapeutic guidance, and frequently poor outcomes and was initially misdiagnosed and treated with topical antibiotics and corticosteroids.

Navigating Standard of Care for Ophthalmic Infections

Herpes simplex keratitis management centers on topical and systemic antivirals with adjunctive anti-inflammatory and supportive measures. Four international, randomized, multicenter clinical trials have demonstrated that ganciclovir gel is at least as effective as acyclovir ointment for the treatment of HSV keratitis, with lower rates of blurred vision, eye irritation, and punctate keratitis, while oral ganciclovir was orally administered 1000 mg 3 times per day for 8 weeks with 0.15% ganciclovir ophthalmic gel, 4 times per day, and 0.1% fluorometholone eye drops, 3 times per day, achieving cure rates of 0.0%, 36.7%, 76.7%, 90.0% and 93.3% respectively at each follow-up time point compared with 0.0%, 3.3%, 16.7%, 30.0% and 43.3% respectively in the control group (χ(2) = 20.00, 16.433, 22.571, 22.636 and 17.330; P < 0. 001). Prolonged use of antivirals administered for at least 4 weeks protected from recurrences of ocular herpetic disease better than placebo (RR 0.56; 95% CI 0.45-0.70) NNT 6 (4-11), decreased recurrences with stromal keratitis (RR 0.55; 95% CI 0.35-0.85) NNT 17 (10-50), with acyclovir better than placebo (RR 0.59; 95% CI 0.46-0.74) NNT 8 (5-14) but not different from valacyclovir (RR 1.0; 95% CI 0.37-2.70), while for herpes zoster ophthalmicus diagnosed within 72 hours of skin eruption, persistent ocular lesions after 6 months were observed in 2/56 people in the valacyclovir group compared with 1/54 people in the acyclovir group (risk ratio (RR) 1.93 (95% CI 0.18 to 20.65)). For neurotrophic keratopathy secondary to herpes simplex keratitis, combined treatment of 0.05% CsA eye drops (1 drop 4 times daily), a silicone hydrogel bandage contact lens, and 0.15% ganciclovir ophthalmic gel (1 drop 3 times daily) achieved complete corneal healing by 13.3% by week 2, 60.0% by week 3, 86.7% by week 4, and 100.0% by week 8, with mean (SD) time to healing being 3.8 (1.8) weeks (range, 2-8 weeks).

Bacterial conjunctivitis and corneal ulcer treatment relies on topical fluoroquinolones and fortified antibiotics with comparable efficacy in studied populations. Topical moxifloxacin enables a dosing strategy of three times daily for 5 days, has a near neutral pH (6.8), and is the first ophthalmic antibacterial in Europe provided as a multidose, self-preserved, topical solution, with favourable area under the concentration-time curve from time zero to 24 hours (AUC(24))/minimum inhibitory concentration ratio required to inhibit the growth of 90% of organisms (MIC(90)). Besifloxacin ophthalmic suspension 0.6% at 1 drop in the affected eye(s) 3 times daily (4-12 hours apart) for 7 days achieved clinical resolution (73.3% vs 43.1%, respectively, in one of the studies [P < 0.001]; 45.2% vs 33.0% in the other [P = 0.008]) and microbial eradication (88.3% vs 60.3% [P < 0.001] and 91.5% vs 59.7% [P < 0.001], respectively) versus vehicle, and was noninferior to moxifloxacin ophthalmic solution 0.5% for clinical resolution (58.3% and 59.4%, respectively; 95% CI, -9.48 to 7.29). For bacterial corneal ulcers of 2-8 mm size, monotherapy with moxifloxacin (0.5%) or gatifloxacin (0.3%) showed no statistically significant difference in mean time to heal compared with combination therapy of cefazolin (5%) and tobramycin (1.3%) (P = 0.98), with 57 patients (93%) healed and 4 (7%) treatment failures, while preoperative application of povidone-iodine remains the standard protocol for the prevention of postoperative endophthalmitis and intracameral cefuroxime administered at the conclusion of surgery significantly reduces the risk of endophthalmitis.

Fungal and Acanthamoeba keratitis require intensive topical antifungals, systemic triazoles in selected cases, and standardized biguanide-based protocols with surgical intervention for progressive disease. Topical voriconazole was more likely to result in therapeutic keratoplasty compared with natamycin [relative risk (RR) 1.89 95% CI: 1.14, 3.12] with a number needed to treat of 13 (95% CI: 7, 50), and final visual acuity was significantly better with natamycin compared with voriconazole [weighted mean difference (WMD) 0.13, 95% CI 0.00, 0.27], while Purpureocillium lilacinum showed high minimum inhibitory concentrations (MICs) to amphotericin B, 5-flucytosine and fluconazole and low MICs to triazoles (voriconazole, isavuconazole, posaconazole, itraconazole), treated with supplementary oral voriconazole and voriconazole eye drops for 20-96 days. Intensive topical voriconazole and amphotericin B, along with systemic voriconazole, were initiated for Aspergillus flavus keratitis occurring three months after penetrating keratoplasty, progressing to graft melting and corneal perforation requiring therapeutic PKP, open sky vitrectomy, and removal of the posterior chamber intraocular lens (PC-IOL). For acanthamoeba keratitis, the Orphan Drug for Acanthamoeba Keratitis (ODAK) trial randomized eyes to polyhexamethylene biguanide (PHMB) 0.08% monotherapy or PHMB 0.02% plus propamidine 0.1% combination therapy and found similar 12-month cure rates and visual outcomes, while in vitro cysts were most susceptible to natamycin, followed by povidone-iodine, BZC, PHMB, propamidine, and CHG, with none of the strains susceptible to VRCZ.

Targeting Unmet Needs in Ophthalmic Infection Treatment

Recent literature highlights persistent complications, antimicrobial resistance, and diagnostic delays as central challenges in ophthalmic infections. Targeted populations include contact lens wearers, neonates, and patients undergoing intraocular procedures, alongside infections caused by resistant bacterial, viral, and fungal pathogens.

• Contact lens wearers, including post-penetrating keratoplasty patients: CL-associated infectious keratitis occurred in 9 patients following PK, more frequently in males (66%), with mean age of 54.5 ± 11.8 years old and contact lenses used for an average of 9.1 ± 10.8 months before development of keratitis, with complications including central corneal haze (N = 8), chronic corneal epithelial defects (N = 3), perforation (N = 3), endophthalmitis (N = 1), and enucleation (N = 1), and three grafts required repeat PK. All 7 cases of Fusarium spp. keratitis diagnosed between 2004 and 2023 with Fusarium solani, and 75% of Beauveria bassiana keratitis cases, related a history of contact lens use, with annual incidence of contact lens-associated keratitis of 2-4/10 000 and due to bacteria in 90% of cases.

• Multidrug-resistant Gram-positive and Pseudomonas ocular infections: According to the ARMOR surveillance program (2009-2020), methicillin resistance reached 45.9% of intraocular Staphylococcus aureus and 47.9% of coagulase-negative staphylococci (CoNS), with multidrug resistance exceeding 70% among methicillin-resistant intraocular isolates. Vancomycin remains the standard of care for severe Gram-positive ocular infections, but its ophthalmic use is constrained by limited ocular surface tolerability, physical incompatibility with intravitreal ceftazidime, and an association with hemorrhagic occlusive retinal vasculitis, driving investigation of peptoids, Esc(1-21) and Esc(1-21)-1c peptides, phage therapy, and virus-like mechano-bactericidal nanomotor (VMSNT) for MRSA-infected keratitis and endophthalmitis.

• Fungal keratitis and fungal endophthalmitis with biofilm formation: Fungal keratitis is prone to causing blindness, with current antifungal drugs possessing transient residence time on the ocular surface and low bioavailability deficiencies. In Makassar, no fungal elements were detected through microscopy or culture, however PCR could identify 5 positive samples (6%) with predominance of Candida species including Candida parapsilosis, Lodderomyces beijingensis, and Trichophyton rubrum. In Fusarium spp. keratitis, all cases required early penetrating keratoplasty, with three infection recurrences and two cases progressing to phthisis bulbi, while microbial biofilms involving Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans complicate keratitis, blepharitis, and endophthalmitis particularly in patients using contact lenses or intraocular implants.

• Viral keratitis requiring rapid differential diagnosis and new targets: 48 (29.6%) out of the total of 162 (100%) eye specimen were positive, with dominant prevalence VZV (12.3%) and HSV-1 (11.7%) followed by AdV (4.9%) and HSV-2 (0.6%), and 4 (8.3%) coinfections within the samples (HSV-1 and VZV). Aqueous humor samples demonstrated superior virus detection ability, and SGK1 was upregulated in human corneal epithelial cells and corneal tissues of BALB/c mice infected with HSV-1, with inhibitor GSK 650394 reducing SGK1 expression, HSV-1 replication, and apoptosis, while antiviral drugs only work during active viral replication, and viral resistance has been recorded in numerous cases.

• Neonates at risk for ophthalmia neonatorum and surgical patients needing safer antisepsis: Only 0.5% erythromycin ophthalmic ointment is available in the United States for neonatal ocular prophylaxis, which is ineffective against C. trachomatis, with 12 infants diagnosed with chlamydial ophthalmia neonatorum in Botswana despite 1% tetracycline prophylaxis at birth. Pre-operative antisepsis with 5% povidone-iodine often leads to foreign body sensation, postoperative eye pain, persistent corneal epithelial defects, and risk of keratitis, while 39 cases of severe corneal chlorhexidine toxicity were reported and thirteen patients underwent corneal transplantation because of severe vision loss.