Effect of polyhexanide and gentamycin on human osteoblasts and endothelial cells

QUESTIONS UNDER STUDY

Infection of total joint replacements is painful, disabling and difficult to treat because of the increasing bacterial resistance against antibiotics. In view of this, antiseptics show limited bacterial tolerance and have a broad-spectrum antimicrobial activity. However, the application of antiseptics to bone is insufficiently studied in literature. Therefore, we investigated the biocompatibility of the antiseptic polyhexanide with bone related cells and asked whether supplementation to bone cement is appropriate in the management of total arthroplasty infections.

METHODS

We performed an in vitro study with immortalised human foetal osteoblast cells (hFOB 1.19) and human endothelial cells (EAhy 926). The cultured cells were exposed to media containing various concentrations of gentamicin (12.5-800 microg/ml) and polyhexanide (0.0006-0.01%) for six hours. We measured the phase-contrast microscopy images, the cell viability, cell number and the alkaline phosphatase activity as a parameter for osteogenic function.

RESULTS

The exposure of hFOB and endothelial cells to polyhexanide showed a severe reduction of viability and cell number. Gentamicin did not have negative effects on hFOB and endothelial cell number and viability. The alkaline phosphatase activity of hFOB showed a significant decrease after exposure to polyhexanide and gentamicin. The viability and the cell number of endothelial cells seem more negatively affected by polyhexanide than the parameters of the hFOB-cells.

CONCLUSIONS

The exposure of human osteoblasts and endothelial cells to polyhexanide at concentrations with questionable antibacterial activity resulted in severe cell damage whereas exposure to high dosed gentamicin did not. These results raise questions as to the feasibility of using antiseptics in bone cement for the treatment of total arthroplasty infections. Further in vivo studies are necessary to show the in vivo relevance of these in vitro findings.

[Painless acanthamoeba keratitis]

A 37-year-old contact lens wearer was treated for herpes simplex keratitis. After an initial improvement the keratitis became much worse. An annular infiltrate gave rise to the suspicion of acanthamoeba keratitis even though the patient was not in pain. This diagnosis was confirmed by histological and microbiological examination of the corneal disc after keratoplasty. Acanthamoeba keratitis should be considered even in the absence of pain, especially when the patients are contact lens wearers.

Metformin: preventable lactic acidosis

A French analysis of reports of adverse effects shows that lactic acidosis due to metformin is preventable.

A Pre-application Drop Containing Carboxymethylcellulose Can Reduce Multipurpose Solution-Induced Corneal Staining

PURPOSE

Use of polyhexanide based multipurpose solutions (MPSs) for contact lens disinfection has been linked to low-grade corneal staining. In vitro data suggest that carboxymethylcellulose (CMC) may neutralize polyhexanides. The purpose of this investigation was to determine whether a pre-application drop of CMC reduces polyhexanide staining in vivo.

METHODS

Thirty adapted soft contact lens (SCL) wearers participated in this investigator-masked, randomized, two-way cross-over study. Subjects wore a new Group II lens (alphafilcon A, 66% water) daily for 4 weeks and disinfected lenses using a MPS containing 0.0001% polyaminopropyl biguanide. A lens lubricant containing either CMC or povidone as the primary viscolyzer was applied to the lens each day before lens wear. Biomicroscopic signs and symptomatology were assessed. The difference in scores, 0 to 4 weeks and the difference between lubricants were analyzed.

RESULTS

The cumulative fluorescein staining scores for combined eyes demonstrated a significant increase over time (e.g., cumulative staining score; p=0.004 and p<0.001 for CMC and povidone, respectively, matched pairs t-test, two-tailed), suggesting that for both lubricants the staining worsened with wear. This effect was expected and likely driven by the MPS. However, the mean cumulative staining scores for CMC and povidone were 2.8 and 2.6 out of 20 possible at baseline, increasing to 4.9 and 7.1 at 4 weeks, respectively. The increases were significantly different (p=0.003, matched pairs t-test, two-tailed) suggesting a greater increase in corneal staining for the povidone lubricant. The symptom scores were not significantly different, 0 to 4 weeks by regimen or between preinstillation drops.

CONCLUSIONS

These results suggest that a CMC-containing preapplication drop can reduce corneal staining resulting from disinfection with a polyhexanide MPS. This result is consistent with a proposed mechanism for CMC to neutralize cationic disinfectants and may offer clinicians another means to reduce this type of corneal staining.

Acidose lactique et metformine

OBJECTIVE

The aims of this review are to precise the pathophysiological mechanisms leading to biguanide-associated lactic acidosis, to give elements of diagnosis, and to underline the precautionary conditions for prescribing these drugs by an improvement in physicians and patient's education.

DATA SOURCES

A PubMed database research in English and French language reports published until December 2005. The keywords were: lactic acidosis, metformin, biguanide, diabetes mellitus.

DATA EXTRACTION

Data in selected articles were reviewed, clinical and basic science research relevant informations were extracted.

DATA SYNTHESIS

Metformin, which is an oral antidiabetic agent, is the only one biguanide available in France. It acts by enhancing the sensitivity to insulin by a decrease in the hepatic glucose production and an increase in its peripheral use. In term of glycemic control, it has the same efficiency than the other hypoglycemic agents. It represents the treatment of choice for overweight type 2 diabetic patients because of its beneficial effects on the weight loss and on the cardiovascular complications. The incidence of metformin-associated lactic acidosis is very low when contra-indications and appropriate rules for prescribing this drug are respected. The relationship between metformin and lactic acidosis remains largely controversial. In practical, we can distinguish three situations which have different prognosis. In the first case, metformin seems to be responsible for lactic acidosis because of self-poisoning or accidental overdose, and prognosis is good. In the second case, the association between metformin and lactic acidosis is coincidental rather than causal, and may be induced by an underlying organ failure. In the last case there is a cause of lactic acidosis which is worsened by a precipitating factor leading to metformin accumulation. The 2 latter situations are very severe as mortality rate is about 50%. Symptomatic treatments and renal replacement therapy which allows metformin removal are the curative treatment. Prevention is essential. It requires the respect of metformin contraindications and a better education of physicians and patients for a safe prescription.

CONCLUSION

Due to its beneficial effects, metformin is the gold standard treatment for overweight type 2 diabetic patients. The essential precautionary conditions for prescribing metformin as well as the respect of its contra-indications permit largely to prevent lactic acidosis. This complication is serious when it is associated with intercurrent illnesses and metformin accumulation. The curative treatment is based on renal replacement therapy. Prevention only rests on the respect of the contra-indications. Education of physicians and patients concerning the rules of prescription remains essential.

Polyhexamethylenebiguanide hydrochloride exposure and erythema multiforme in a physician

A 52-year-old woman physician developed recurrent erythema multiforme. Occupational and environmental exposure assessment suggested a disinfectant containing polyhexamethylenebiguanide hydrochloride (PHMB), Phagosept. Elimination of the product was followed by disappearance of symptomatology. Literature search revealed cases of sensitization and anaphylaxis due to contact with PHMB, but to our knowledge, this is the first report on PHMB-induced erythema multiforme.

Polyhexamethylene biguanide for treatment of external genital warts: a prospective, double-blind, randomized study

Genital human papillomavirus infection is one of the most common sexually transmitted diseases. Polyhexamethylene biguanide is a new agent, that has been demonstrated to have potent in vivo antiviral effects in animal and in human models. The present prospective, double-blind, randomized, placebo (vehicle-controlled) trial evaluated the efficacy and safety of daily patient-applied polyhexamethylene biguanide for up to 16-weeks for the treatment of external genital warts. Wart recurrence was investigated during a 12-week treatment-free follow-up period. In the intent-to-treat analysis, baseline warts cleared from 49 of 94 (52%) patients treated with polyhexamethylene biguanide cream versus and 3 of 95 (4%) placebo patients; the differences between the groups treated with placebo and polyhexamethylene biguanide were significant (P < 0.0001). For subjects who completed the follow-up period, recurrence rates after a complete response were 19% (9 of 48 patients) in the polyhexamethylene biguanide cream group, 17% cream group, and 0% (0 of 3) in the placebo group. There were no systemic reactions, although local skin reactions (generally of mild or moderate severity) were common in the polyhexamethylene biguanide cream group. Local reactions caused two patients to discontinue treatment. The most frequently reported local skin reactions were erythema, excoriation or flaking, and erosion. Patient-applied polyhexamethylene biguanide cream is effective for the treatment of external genital warts and has a favorable safety profile.

Corneal Staining and Subjective Symptoms With Multipurpose Solutions as a Function of Time

PURPOSE

Short-term changes in corneal staining and ocular symptoms were assessed at defined intervals to evaluate combinations of three soft lenses and four multipurpose solutions.

METHODS

A series of pilot studies were conducted over 11 months using a double-masked, randomized, crossover design. Asymptomatic, adapted, daily-wear soft lens users wore group II or IV soft hydrophilic or silicone hydrogel lenses for a maximum period each day. Before wear, new lenses were soaked overnight in one of four multipurpose solutions: Alcon OPTI-FREE Express MPDS, Bausch & Lomb ReNu MultiPlus Multipurpose Solution, CIBA Vision SOLO-Care PLUS Multipurpose Solution, or AMO Complete MoisturePLUS. Subjects rated comfort and ocular symptoms. Corneal staining type and area were evaluated at baseline and after lens removal.

RESULTS

Significantly increased extent of corneal staining, defined as the proportion of corneal zones showing staining of grade 1 or more severe, was observed at 1 and 2 hours when subjects wore group II lenses soaked in the polyhexamethylene biguanide-based systems. Significantly increased extent of staining was observed at 2 hours when subjects used silicone hydrogel lenses soaked in regimen 4. When subjects used regimen 1 and wore group II lenses, only a minimal staining response was observed at 1 and 2 hours of wear. Significant symptoms were not correlated with extent of staining.

CONCLUSIONS

This study design is a promising tool that can discriminate between the performance of different soft lens and multipurpose solution combinations rapidly using small patient samples. With some lens-care product combinations, corneal appearance may vary according to the time of day the patient is examined.

Oral antidiabetic agents: current role in type 2 diabetes mellitus

Type 2 diabetes mellitus is a progressive and complex disorder that is difficult to treat effectively in the long term. The majority of patients are overweight or obese at diagnosis and will be unable to achieve or sustain near normoglycaemia without oral antidiabetic agents; a sizeable proportion of patients will eventually require insulin therapy to maintain long-term glycaemic control, either as monotherapy or in conjunction with oral antidiabetic therapy. The frequent need for escalating therapy is held to reflect progressive loss of islet beta-cell function, usually in the presence of obesity-related insulin resistance. Today's clinicians are presented with an extensive range of oral antidiabetic drugs for type 2 diabetes. The main classes are heterogeneous in their modes of action, safety profiles and tolerability. These main classes include agents that stimulate insulin secretion (sulphonylureas and rapid-acting secretagogues), reduce hepatic glucose production (biguanides), delay digestion and absorption of intestinal carbohydrate (alpha-glucosidase inhibitors) or improve insulin action (thiazolidinediones). The UKPDS (United Kingdom Prospective Diabetes Study) demonstrated the benefits of intensified glycaemic control on microvascular complications in newly diagnosed patients with type 2 diabetes. However, the picture was less clearcut with regard to macrovascular disease, with neither sulphonylureas nor insulin significantly reducing cardiovascular events. The impact of oral antidiabetic agents on atherosclerosis--beyond expected effects on glycaemic control--is an increasingly important consideration. In the UKPDS, overweight and obese patients randomised to initial monotherapy with metformin experienced significant reductions in myocardial infarction and diabetes-related deaths. Metformin does not promote weight gain and has beneficial effects on several cardiovascular risk factors. Accordingly, metformin is widely regarded as the drug of choice for most patients with type 2 diabetes. Concern about cardiovascular safety of sulphonylureas has largely dissipated with generally reassuring results from clinical trials, including the UKPDS. Encouragingly, the recent Steno-2 Study showed that intensive target-driven, multifactorial approach to management, based around a sulphonylurea, reduced the risk of both micro- and macrovascular complications in high-risk patients. Theoretical advantages of selectively targeting postprandial hyperglycaemia require confirmation in clinical trials of drugs with preferential effects on this facet of hyperglycaemia are currently in progress. The insulin-sensitising thiazolidinedione class of antidiabetic agents has potentially advantageous effects on multiple components of the metabolic syndrome; the results of clinical trials with cardiovascular endpoints are awaited. The selection of initial monotherapy is based on a clinical and biochemical assessment of the patient, safety considerations being paramount. In some circumstances, for example pregnancy or severe hepatic or renal impairment, insulin may be the treatment of choice when nonpharmacological measures prove inadequate. Insulin is also required for metabolic decompensation, that is, incipient or actual diabetic ketoacidosis, or non-ketotic hyperosmolar hyperglycaemia. Certain comorbidities, for example presentation with myocardial infarction during other acute intercurrent illness, may make insulin the best option. Oral antidiabetic agents should be initiated at a low dose and titrated up according to glycaemic response, as judged by measurement of glycosylated haemoglobin (HbA1c) concentration, supplemented in some patients by self monitoring of capillary blood glucose. The average glucose-lowering effect of the major classes of oral antidiabetic agents is broadly similar (averaging a 1-2% reduction in HbA1c), alpha-glucosidase inhibitors being rather less effective. Tailoring the treatment to the individual patient is an important principle. Doses are gradually titrated up according to response. However, the maximal glucose-lowering action for sulphonylureas is usually attained at appreciably lower doses (approximately 50%) than the manufacturers' recommended daily maximum. Combinations of certain agents, for example a secretagogue plus a biguanide or a thiazolidinedione, are logical and widely used, and combination preparations are now available in some countries. While the benefits of metformin added to a sulphonylurea were initially less favourable in the UKPDS, longer-term data have allayed concern. When considering long-term therapy, issues such as tolerability and convenience are important additional considerations. Neither sulphonylureas nor biguanides are able to appreciably alter the rate of progression of hyperglycaemia in patients with type 2 diabetes. Preliminary data suggesting that thiazolidinediones may provide better long-term glycaemic stability are currently being tested in clinical trials; current evidence, while encouraging, is not conclusive. Delayed progression from glucose intolerance to type 2 diabetes in high-risk individuals with glucose intolerance has been demonstrated with troglitazone, metformin and acarbose. However, intensive lifestyle intervention can be more effective than drug therapy, at least in the setting of interventional clinical trials. No antidiabetic drugs are presently licensed for use in prediabetic individuals.

Oral antihyperglycemic therapy for type 2 diabetes mellitus

Diabetes mellitus is a chronic disease that is growing in prevalence worldwide. Pharmacologic therapy is often necessary to achieve optimal glycemic control in the management of diabetes. Orally administered antihyperglycemic agents (OHAs) can be used either alone or in combination with other OHAs or insulin. The number of available OHAs has increased significantly in the last decade, which translates into more therapeutic options and complex decision-making for physicians. This review article is designed to help with these decisions. We review the mechanism of action, efficacy and side effects of the different classes of OHAs (alpha-glucosidase inhibitors, biguanides, insulin secretagogues, insulin sensitizers and intestinal lipase inhibitor) and discuss the current recommendations for their use.

Oral Antidiabetic Therapy in Patients with Heart Disease

Five types of oral antihyperglycemic drugs are currently approved for the treatment of diabetes: biguanides, sulfonylureas, meglitinides, glitazones, and alpha-glucosidase inhibitors. The cardiovascular effects of the most commonly used antidiabetic drugs in these groups are briefly reported, in an attempt to improve knowledge and awareness regarding their influences and potential risks when treating patients with coronary artery disease (CAD). Regarding biguanides, gastrointestinal disturbances such as diarrhea are frequent, and the intestinal absorption of group B vitamins and especially folate is impaired during chronic therapy. This deficiency may lead to increased plasma homocysteine levels which, in turn, accelerate the progression of vascular disease due to adverse effects on platelets, clotting factors, and endothelium. The existence of a graded association between homocysteine levels and overall mortality in patients with CAD is well established. In addition, metformin may lead to lethal lactic acidosis, especially in patients with clinical conditions that predispose to this complication, such as heart failure or recent myocardial infarction. Sulfonylureas avoid ischemic preconditioning. During myocardial ischemia, they may prevent the opening of the ATP-dependent potassium channels, impeding the necessary hyperpolarization that protects the cell by blocking calcium influx. Meglitinides may exert similar effects, due to their analogous mechanism of action. During treatment with glitazones, edema has been reported in 5% of patients, and these drugs are contraindicated in diabetics with NYHA class III or IV cardiac status. The long-term effects of alpha-glucosidase inhibitors on morbidity and mortality rates and on diabetic micro- and macrovascular complications are yet unknown. The combined sulfonylurea/metformin therapy reveals additive effects on mortality. It is concluded that(1) four of the five oral antidiabetic drug groups present proven or potential cardiac hazards;(2) these hazards are not mere "side effects", but are deeply rooted in the drugs' mechanism of action;(3) current data indicate that the combined glibenclamide/metformin therapy seems to present special risk and should be avoided in the long-term management of type 2 diabetics with proven CAD; and(4) customized antihyperglycemic pharmacological approaches should be investigated for optimal treatment of diabetic patients with heart disease.

Polyhexamethylbiguanid (PHMB) zur pr�operativen Antisepsis bei Kataraktoperation

BACKGROUND

We examined the efficacy and tolerability of Lavasept (polyhexamethylenbiguanid or PHMB)-an iodine-free antiseptic-in comparison to polyvinylpyrolidon iodine and Ringer's solution, as an alternative preoperative antiseptic.

PATIENTS AND METHODS

In a randomized controlled double-blind trial 3 drops of Lavasept, 1.25%, PVP-iodine or Ringer's solution were applied preoperatively in 29 patients. The number of colony forming units (cfu) grown from conjunctival smears and conjunctival hyperaemia, corneal epitheliopathy and ocular surface pain were assessed preoperatively, intraoperatively and 1 day postoperatively.

RESULTS

Despite intraoperative application of PVP-iodine, 40% of patients receiving Ringers solution still presented with more than 5 colony forming units (cfu) at the end of the procedure, while all patients that had additional preoperative Lavasept or PVP-iodine achieved relative sterility with less than 5 cfu (p < 0.05). While the effect of Lavasept lasted until the next day, conjunctival microbial colonisation recurred in eyes treated with PVP-iodine. As expected conjunctival hyperaemia and corneal epitheliopathy increased significantly postoperatively but no differences were observed between the 3 solutions tested.

CONCLUSION

The preoperative application of Lavasept reduces the conjunctival flora safely and effectively. The microbicidal efficacy is equal to PVP-iodine, but potentially longer lasting. No signs of local or systemic intolerability were observed. Lavasept may be used as a potential alternative preoperative antiseptic and is suitable for iodine-intolerant patients.

Should we screen diabetic patients using biguanides for megaloblastic anaemia?

BACKGROUND

Patients taking biguanides on a continuous basis sometimes develop vitamin B12 deficient megaloblastic anaemia. The prevalence of this side effect has not been estimated.

METHODS

We screened 600 patients with type 2 diabetes treated with biguanides (phenformin or metformin) for a mean of 11.8 years (SD: 3.6 years) with complete blood counts, red cell indices and red cell morphology. If this showed macrocytosis, we measured total serum vitamin B12 and antiparietal cells antibodies (APCA). Patients with macrocytosis and low serum vitamin B12 levels were treated with cyanocobalamin 1 mg injection daily for seven days.

RESULTS

Fifty-four (9%) of the patients had megaloblastic anaemia with low serum total vitamin B12 levels, only three (0.5%) also had abnormally raised APCA. All 54 patients responded to cyanocobalamin with a reticulocyte increase within 10 days.

CONCLUSION

Annual screening for megaloblastic anaemia in patients on long term treatment with biguanides may be worthwhile. The anaemia is easily remediable and does not necessitate withdrawal of the drug.

Oral antihyperglycemic agents during pregnancy and lactation: a review

The treatment approach of diabetes mellitus during pregnancy requires a combination of diet, exercise, multiple home glucose determinations and intensive insulin regimens. During the last decade there was an increased interest in the use of oral antihyperglycemic agents (OAHAs) as an alternative to insulin in achieving good glycemic control. OAHAs are divided into four groups: derivatives of sulfonylurea, biguanides, glucosidase inhibitors and thiazolidinediones. This review describes the possible teratogenic effects of the use of OAHAs during pregnancy and the effects of these drugs during lactation. Animal and human studies assessing the teratogenic effects of OAHAs have yielded conflicting data because the risk of major malformations in infants of mothers with diabetes appears to be related to maternal glycemic control rather than the antidiabetic therapy. A major concern with the use of OAHAs during pregnancy is neonatal hypoglycemia, which may be severe and persist for days. Therefore, insulin is still the drug of choice because it has not been implicated as a teratogen in human pregnancies. In addition, because of the lack of data regarding the use of OAHAs in pregnancy, we cannot draw firm conclusions about all of the available drugs. However, OAHAs, especially glibenclamide (glyburide), may be beneficial in a situation where the proper use of insulin is problematic. Because there are very limited clinical data on the exposure of OAHAs to the infant via breast milk, and the potentially serious effect of neonatal hypoglycemia, the safest recommendation is not to breast feed while taking OAHAs. Well-conducted, prospective, controlled studies regarding the feasibility of OAHAs in pregnant women with diabetes and during lactation are needed.

Involvement of organic cation transporter 1 in the lactic acidosis caused by metformin

Biguanides are a class of drugs widely used as oral antihyperglycemic agents for the treatment of type 2 diabetes mellitus, but they are associated with lactic acidosis, a lethal side effect. We reported previously that biguanides are good substrates of rat organic cation transporter 1 (Oct1; Slc22a1) and, using Oct1(-/-) mice, that mouse Oct1 is responsible for the hepatic uptake of a biguanide, metformin. In the present study, we investigated whether the liver is the key organ for the lactic acidosis. When mice were given metformin, the blood lactate concentration significantly increased in the wild-type mice, whereas only a slight increase was observed in Oct1(-/-) mice. The plasma concentration of metformin exhibited similar time profiles between the wild-type and Oct1(-/-) mice, suggesting that the liver is the key organ responsible for the lactic acidosis. Furthermore, the extent of the increase in blood lactate caused by three different biguanides (metformin, buformin, and phenformin) was compared with the abilities to reduce oxygen consumption in isolated rat hepatocytes. When rats were given each of these biguanides, the lactate concentration increased significantly. This effect was dose-dependent, and the EC(50) values of metformin, buformin, and phenformin were 734, 119, and 4.97 microM, respectively. All of these biguanides reduced the oxygen consumption by isolated rat hepatocytes in a concentration-dependent manner. When the concentration required to reduce the oxygen consumption to 75% of the control value (from 0.40 to 0.29 micromol/min/mg protein) was compared with the EC(50) value obtained in vivo, a clear correlation was observed among the three biguanides, suggesting that oxygen consumption in isolated rat hepatocytes can be used as an index of the incidence of lactic acidosis.

[Role of thyroid pathology in pathogenesis of arterial hypertension in diabetes]

190 patients with diabetes mellitus (DM) were examined: 24 patients with DM type 1 and 166 with DM type 2. Frequency of arterial hypertension (AH) in diabetics is higher than in population. AH in different DM types varies by pathogenesis. Symptomatic renal AH is typical for DM1, essential AH combining with renal one in 1/3 of cases--for DM2. Treatment of AH and DM often provokes hypothyroidism which can be iatrogenic because of continuous intake of sugar reducing and antihypertensive drugs with antithyroid and strumogenic actions. Hypothyroidism aggravates an AH course: arterial pressure becomes high and resistant to hypotensive therapy. DM makes difficulties in selection of hypotensive drugs as many of them alter metabolism and due to negative attitude of the patients to continuous intake of sugar reducing, antihypertensive drugs, thyroid hormones. Therefore, hypertensive diabetics should be prepared for treatment psychologically and receive only prolonged hypotensive drugs. In DM with AH medication of choice is ACE inhibitors as they are nephroprotective, had no negative effect on carbohydrate, fat metabolism and thyroid system.

Asymptomatic corneal staining associated with the use of balafilcon silicone-hydrogel contact lenses disinfected with a polyaminopropyl biguanide-preserved care regimen

PURPOSE

To compare subjective symptoms and signs in a group of individuals who wear silicone-hydrogel lenses on a daily wear basis while they sequentially used two differing care regimens.

METHODS

Fifty adapted soft-lens wearers were fitted with a silicone-hydrogel lens material (PureVision, Bausch & Lomb). The lenses were worn on a daily wear basis for two consecutive 1-month periods, during which the subjects used either a Polyquad (polyquaternium-1) -based system or a polyaminopropyl biguanide (PHMB) -based system, using a double-masked, randomized, crossover experimental design.

RESULTS

Significant levels of relatively asymptomatic corneal staining were observed when subjects used the PHMB-based system, with 37% of subjects demonstrating a level of staining consistent with a classical solution-based toxicity reaction. Only 2% of the subjects exhibited such staining when using the Polyquad-based system. These results were significantly different (p < 0.001). Significant symptoms were not correlated with the degree of staining, with no differences in lens comfort or overall preference being reported between the regimens (p = NS). The only statistically significant difference in symptoms related to minor differences in stinging after lens insertion being reported, with the Polyquad-based system demonstrating less stinging (p < 0.008).

CONCLUSIONS

Practitioners who fit silicone-hydrogel contact lenses on a daily wear basis should be wary of the potential for certain PHMB-containing multipurpose care systems to invoke corneal staining. Switching to non-PHMB based regimens will eliminate this complication in most instances.