Spaced administration of PA32540 and clopidogrel results in greater platelet inhibition than synchronous administration of enteric-coated aspirin and enteric-coated omeprazole and clopidogrel

PA32540 for the secondary prevention of cardiovascular disease in patients at risk for aspirin-associated gastric ulcers

Prescribed in patients with a history of myocardial infarction, stroke, transient ischemic attack, coronary intervention or bypass surgery, aspirin is one of the medications most commonly used in the secondary prevention of cardiovascular diseases. It has become a mainstay of therapy after years of solid evidence supporting its efficacy in clinical trials. However, a number of risks and side effects accompany its benefits, including the notable risk of bleeding and gastrointestinal side effects. Numerous mechanisms have been proposed to attenuate these effects to promote adherence and to expand the population for which aspirin is a reasonable treatment option. A polypill or combination formulation that includes a proton pump inhibitor, a drug commonly prescribed alongside aspirin, is one potential avenue of therapy. One such combination pill, PA32540, has undergone Phase I and Phase III trials and shows promising safety and efficacy results in these preliminary trials.

PA32540 (a coordinated-delivery tablet of enteric-coated aspirin 325 mg and immediate-release omeprazole 40 mg) versus enteric-coated aspirin 325 mg alone in subjects at risk for aspirin-associated gastric ulcers: results of two 6-month, phase 3 studies

BACKGROUND

Discontinuations and/or interruptions in aspirin therapy for secondary cardioprotection due to upper gastrointestinal (UGI) complications or symptoms have been shown to increase the risk for subsequent cardiovascular events. PA32540 is a coordinated-delivery, combination tablet consisting of enteric-coated aspirin (EC-ASA) 325 mg and immediate-release (IR) omeprazole 40 mg.

METHODS

Two identically-designed, 6-month, randomized, double-blind trials evaluated PA32540 vs. EC-ASA 325 mg in a secondary cardiovascular disease prevention population taking aspirin 325 mg daily for ≥3 months and at risk for ASA-associated gastric ulcers (GUs). The combined study population was 1049 subjects (524 randomized to PA32540, 525 to EC-ASA 325 mg). The primary endpoint was the occurrence of endoscopically-determined gastric ulceration over 6 months. Safety outcomes included the rates of major adverse cardiovascular events (MACE) and UGI symptoms.

RESULTS

Significantly fewer PA32540-treated subjects (3.2%) developed endoscopic GUs vs. EC-ASA 325 mg-treated subjects (8.6%) (P < .001). Overall occurrence of MACE was low (2.1%), with no significant differences between treatments in types or incidence of MACE. PA32540-treated subjects had significantly fewer UGI symptoms (P < .001) and significantly fewer discontinuations due to pre-specified UGI adverse events (1.5% vs. 8.2%, respectively; P < .001).

CONCLUSIONS

PA32540 reduced the incidence of endoscopic GUs compared to EC-ASA 325 mg, but with a similar cardiovascular event profile. Due to fewer UGI symptoms, continuation on aspirin therapy was greater in the PA32540 treatment arm.

PA tablets: investigational compounds combining aspirin and omeprazole for cardioprotection

For most patients with prior cardiovascular events, preventing future secondary cardiovascular events requires life-long persistence with antiplatelet therapy. PA tablets (P: proton pump inhibitors; A: aspirin) are investigational compounds that were developed to provide the cardioprotective benefits of aspirin with the upper gastrointestinal protection of a proton pump inhibitor (e.g., omeprazole). The tablets are film-coated, coordinated-release tablets for oral administration that contain 40 mg immediate-release omeprazole and either 81 or 325 mg delayed-release aspirin. The goals of the clinical development program were to demonstrate the following: improved gastrointestinal safety of PA relative to enteric-coated aspirin alone; bioequivalence and comparative bioavailability between the PA compounds and currently marketed enteric-coated aspirin; and long-term safety. Two clinical pharmacology studies were also conducted to study the potential for interaction between PA32540 and clopidogrel.

Pharmacokinetic drug interaction profile of omeprazole with adverse consequences and clinical risk management

BACKGROUND

Omeprazole, a proton pump inhibitor (PPI), is widely used for the treatment of dyspepsia, peptic ulcer, gastroesophageal reflux disease, and functional dyspepsia. Polypharmacy is common in patients receiving omeprazole. Drug toxicity and treatment failure resulting from inappropriate combination therapy with omeprazole have been reported sporadically. Systematic review has not been available to address the pharmacokinetic drug-drug interaction (DDI) profile of omeprazole with adverse consequences, the factors determining the degree of DDI between omeprazole and comedication, and the corresponding clinical risk management.

METHODS

Literature was identified by performing a PubMed search covering the period from January 1988 to March 2013. The full text of each article was critically reviewed, and data interpretation was performed.

RESULTS

Omeprazole has actual adverse influences on the pharmacokinetics of medications such as diazepam, carbamazepine, clozapine, indinavir, nelfinavir, atazanavir, rilpivirine, methotrexate, tacrolimus, mycophenolate mofetil, clopidogrel, digoxin, itraconazole, posaconazole, and oral iron supplementation. Meanwhile, low efficacy of omeprazole treatment would be anticipated, as omeprazole elimination could be significantly induced by comedicated efavirenz and herb medicines such as St John's wort, Ginkgo biloba, and yin zhi huang. The mechanism for DDI involves induction or inhibition of cytochrome P450, inhibition of P-glycoprotein or breast cancer resistance protein-mediated drug transport, and inhibition of oral absorption by gastric acid suppression. Sometimes, DDIs of omeprazole do not exhibit a PPI class effect. Other suitable PPIs or histamine 2 antagonists may be therapeutic alternatives that can be used to avoid adverse consequences. The degree of DDIs associated with omeprazole and clinical outcomes depend on factors such as genotype status of CYP2C19 and CYP1A2, ethnicity, dose and treatment course of precipitant omeprazole, pharmaceutical formulation of object drug (eg, mycophenolate mofetil versus enteric-coated mycophenolate sodium), other concomitant medication (eg, omeprazole-indinavir versus omeprazole-indinavir-ritonavir), and administration schedule (eg, intensified dosing of mycophenolate mofetil versus standard dosing).

CONCLUSION

Despite the fact that omeprazole is one of the most widely prescribed drugs internationally, clinical professionals should enhance clinical risk management on adverse DDIs associated with omeprazole and ensure safe combination use of omeprazole by rationally prescribing alternatives, checking the appropriateness of physician orders before dispensing, and performing therapeutic drug monitoring.