Opigrel A

Uses

Clopidogrel + Aspirin is used for the reduction of thrombotic events as follows:

Recent MI, Recent Stroke or Established Peripheral Arterial Disease

For patients with a history of recent myocardial infarction (MI), recent stroke or established peripheral arterial disease, Clopidogrel + Aspirin has been shown to reduce the rate of a combined endpoint of new ischemic stroke (fatal or not), new MI (fatal or not) and other vascular death.

Acute Coronary Syndrome

For patients with acute coronary syndrome (unstable angina/non-Q-wave MI) including patients who are to be managed medically and those who are to be managed with percutaneous coronary intervention (with or without stent) or CABG. Clopidogrel + Aspirin has been shown to decrease the rate of a combined endpoint of cardiovascular death, MI, or stroke as well as the rate of a combined endpoint of cardiovascular death, MI, stroke, or refractory ischemia.

Opigrel A is also used to associated treatment for these conditions: Acute Coronary Syndrome (ACS), Anxiety, Arthritis, Atherothrombotic cerebral infarction, Cardiovascular Disease (CVD), Cardiovascular Events, Cardiovascular Mortality, Colorectal Adenomas, Colorectal Cancers, Common Cold, Coronary artery reocclusion, Death, Dyspeptic signs and symptoms, Fever, Flu Like Symptom, Flu caused by Influenza, Headache, Heterozygous Familial Hypercholesterolemia, Inflammation, Juvenile Idiopathic Arthritis (JIA), Kawasaki Syndrome, Major Adverse Cardiovascular and Cerebrovascular Events (MACCE), Migraine, Morbidity, Mucocutaneous Lymph Node Syndrome, Muscle Contraction, Myocardial Infarction, Myocardial Infarction (MI), first occurrence, Neuralgia, Pain, Pain caused by Common Cold, Pain, Menstrual, Pericarditis, Polycythemia Vera (PV), Preeclampsia, Rheumatic Pain, Rheumatism, Rheumatoid Arthritis, Rhinosinusitis, Severe Pain, Soreness, Muscle, Spondyloarthropathies, Stroke, Systemic Lupus Erythematosus (SLE), Tension Headache, Thromboembolism, Toothache, Transient Ischemic Attack, Venous Thromboembolism, Acute Inflammation, Atherothrombotic events, Death by myocardial infarction, Moderate Pain, Thrombotic events, Antiplatelet Therapy, Hemodialysis Treatment, Secondary PreventionAcute Coronary Syndrome (ACS), Acute Myocardial Infarction (AMI), Cardiovascular Events, Atherothrombotic events

How Opigrel A works

Acetylsalicylic acid (ASA) blocks prostaglandin synthesis. It is non-selective for COX-1 and COX-2 enzymes . Inhibition of COX-1 results in the inhibition of platelet aggregation for about 7-10 days (average platelet lifespan). The acetyl group of acetylsalicylic acid binds with a serine residue of the cyclooxygenase-1 (COX-1) enzyme, leading to irreversible inhibition. This prevents the production of pain-causing prostaglandins. This process also stops the conversion of arachidonic acid to thromboxane A2 (TXA2), which is a potent inducer of platelet aggregation . Platelet aggregation can result in clots and harmful venous and arterial thromboembolism, leading to conditions such as pulmonary embolism and stroke.

It is important to note that there is 60% homology between the protein structures of COX-1 and COX-2. ASA binds to serine 516 residue on the active site of COX-2 in the same fashion as its binding to the serine 530 residue located on the active site of COX-1. The active site of COX-2 is, however, slightly larger than the active site of COX-1, so that arachidonic acid (which later becomes prostaglandins) manages to bypass the aspirin molecule inactivating COX-2 . ASA, therefore, exerts more action on the COX-1 receptor rather than on the COX-2 receptor . A higher dose of acetylsalicylic acid is required for COX-2 inhibition .

Clopidogrel is metabolized to its active form by carboxylesterase-1. The active form is a platelet inhibitor that irreversibly binds to P2Y₁₂ ADP receptors on platelets. This binding prevents ADP binding to P2Y₁₂ receptors, activation of the glycoprotein GPIIb/IIIa complex, and platelet aggregation.

Dosage

Opigrel A dosage

Recent MI, Recent Stroke, or Established Peripheral Arterial Disease

The recommended daily dose of Clopidogrel + Aspirin one tablet daily.

Acute Coronary Syndrome

For patients with acute coronary syndrome (unstable angina/non-Q-wave MI), Clopidogrel + Aspirin should be initiated with a 4 tablet stat loading dose and then continued at one tablet daily.

Pediatric Use: Safety and effectiveness of Clopidogrel + Aspirin in the pediatric population has not been established.

Side Effects

The drug is generally well tolerated. Side effects that have been reported include abdominal pain, dyspepsia, gastritis, diarrhea, nausea, vomiting, constipation, gastrointestinal hemorrhage, ulceration, neutropenia, rash, palpitation, syncope, drowsiness, asthenia, neuralgia, paresthesia and vertigo.

Toxicity

Lethal doses

Acute oral LD50 values have been reported as over 1.0 g/kg in humans, cats, and dogs, 0.92 g/kg - 1.48 g/kg in albino rats, 1.19 g/kg in guinea pigs, 1.1 g/kg in mice, and 1.8 g/kg in rabbit models .

Acute toxicity

Salicylate toxicity is a problem that may develop with both acute and chronic salicylate exposure . Multiple organ systems may be affected by salicylate toxicity, including the central nervous system, the pulmonary system, and the gastrointestinal system. Severe bleeding may occur. In the majority of cases, patients suffering from salicylate toxicity are volume-depleted at the time of presentation for medical attention. Fluid resuscitation should occur immediately and volume status should be monitored closely. Disruptions in acid-base balance are frequent in ASA toxicity .

The acute toxicity of acetylsalicylic in animals has been widely studied. The signs of poisoning in rats from lethal doses are mild to severe gastroenteritis, hepatitis, nephritis, pulmonary edema, encephalopathy, shock and some toxic effects on other organs and tissues. Mortality has been observed following convulsions or cardiovascular shock. An important differentiating property between various animal species is the ability to vomit toxic doses. Humans, cats and dogs have this ability, but rodents or rabbits do not .

Chronic toxicity and carcinogenesis

Chronic ASA toxicity is frequently accompanied by atypical clinical presentations that may be similar to diabetic ketoacidosis, delirium, cerebrovascular accident (CVA), myocardial infarction (MI) or cardiac failure. Plasma salicylate concentrations should be measured if salicylate intoxication is suspected, even if there no documentation available to suggest ASA was ingested. In older age, nephrotoxicity from salicylates increases, and the risk of upper gastrointestinal hemorrhage is increased, with higher rates of mortality . It is also important to note that ASA toxicity may occur even with close to normal serum concentrations. Prevention of chronic ASA includes the administration of smallest possible doses, avoidance of concurrent use of salicylate drugs, and therapeutic drug monitoring. Renal function should be regularly monitored and screening for gastrointestinal bleeding should be done at regular intervals .

Chronic toxicity studies were performed in rodents. ASA was administered at doses measured to be 2 to 20 times the maximum tolerated clinical dose to mice for up to one year. Negative dose-related effects were seen. These include decreased mean survival time, decreased number of births and progeny reaching an appropriate age for weaning. No evidence of carcinogenesis was found in 1-year studies . At daily doses of 0.24 g/kg/day given for 100 days to albino rats, ASA led to signs to excessive thirst, aciduria, diuresis, drowsiness, hyperreflexia, piloerection, changes in respiration, tachycardia, followed by soft stools, epistaxis, sialorrhea, dacryorrhea and mortality during hypothermic coma in the second study month .

Use in pregnancy and lactation

While teratogenic effects were observed in animals nearly lethal doses, no evidence suggests that this drug is teratogenic in humans . It is advisable, however, to avoid ASA use the first and second trimester of pregnancy, unless it is clearly required. If acetylsalicylic acid containing drugs are ingested by a patient attempting to conceive, or during the first and second trimester of pregnancy, the lowest possible dose at the shortest possible duration should be taken . This drug is contraindicated in the 3rd trimester of pregnancy .

A single dose of clopidogrel at 1500-2000mg/kg was lethal to mice and rats while 3000mg/kg was lethal to baboons. Symptoms of overdose include vomiting, breathing difficulty, gastrointestinal hemorrhage, and prostration. Clopidogrel is irreversibly bound to platelets for their lifetime, which is approximately 11 days. Overdoses of clopidogrel can be treated with platelet transfusions to restore clotting ability.

Precaution

General: As with other anti-platelet agents, this combination drug should be used with caution in patients who may be at risk of increased bleeding from trauma, surgery, or other pathological conditions. If a patient is to undergo elective surgery and an anti-platelet effect is not desired, Clopidogrel + Aspirin should be discontinued 7 days prior to surgery.

GI Bleeding: The combination of Clopidogrel and Aspirin prolongs the bleeding time. So, it should be used with caution in patients who have lesions with a propensity to bleed (such as ulcers).

Thrombotic thrombocytopenic purpura (TTP): TTP has been reported rarely following use of Clopidogrel.

Reye\'s syndrome: Reye\'s syndrome may develop in individuals who have chicken pox, influenza or flu symptoms. This combination is not recommended for use in patients with chicken pox, influenza or flu symptoms.

Nasal polyps or nasal allergies: The combination drug of Clopidogrel and Aspirin should be administered with caution in patients with nasal polyps or nasal allergies.

Hepatic or Renal Impairment: This should be avoided in patients with impaired hepatic and renal function. Aspirin causes sodium and water retention in patients with renal impairment and increases the risk of gastrointestinal bleeding.

Interaction

Salicylates should be used with caution in patients with a history of peptic ulceration or coagulation abnormalities. They may also induce gastro-intestinal haemorrhage occasionally major. Aspirin should be used with caution in patients with impaired renal function, hepatic function (avoid if severe) or in patients who are dehydrated. In large doses, it may also decrease insulin requirements.

Volume of Distribution

This drug is distributed to body tissues shortly after administration. It is known to cross the placenta. The plasma contains high levels of salicylate, as well as tissues such as spinal, peritoneal and synovial fluids, saliva and milk. The kidney, liver, heart, and lungs are also found to be rich in salicylate concentration after dosing. Low concentrations of salicylate are usually low, and minimal concentrations are found in feces, bile, and sweat .

The apparent volume of distribution of clopidogrel is 39,240±33,520L.

Elimination Route

Absorption is generally rapid and complete following oral administration but absorption may be variable depending on the route, dosage form, and other factors including but not limited to the rate of tablet dissolution, gastric contents, gastric emptying time, and gastric pH .

Detailed absorption information

When ingested orally, acetylsalicylic acid is rapidly absorbed in both the stomach and proximal small intestine. The non-ionized acetylsalicylic acid passes through the stomach lining by passive diffusion. Ideal absorption of salicylate in the stomach occurs in the pH range of 2.15 - 4.10. Intestinal absorption of acetylsalicylic acid occurs at a much faster rate. At least half of the ingested dose is hydrolyzed to salicylic acid in the first-hour post-ingestion by esterases found in the gastrointestinal tract. Peak plasma salicylate concentrations occur between 1-2 hours post-administration .

A 75mg oral dose of clopidogrel is 50% absorbed from the intestine. Clopidogrel can be taken with or without food. A meal decreases the AUC of the active metabolite by 57%. The active metabolite of clopidogrel reaches a maximum concentration after 30-60 minutes. Clopidogrel reached a C_max of 2.04±2.0ng/mL in 1.40±1.07h.

The AUC for a 300mg oral dose of clopidogrel was 45.1±16.2ng*h/mL for poor metabolizers, 65.6±19.1ng*h/mL for intermediate metabolizers, and 104.3±57.3ng*h/mL for extensive metabolizers. The C_max was 31.3±13ng/mL for poor metabolizers, 43.9±14ng/mL for intermediate metabolizers, and 60.8±34.3ng/mL for extensive metabolizers.

Half Life

The half-life of ASA in the circulation ranges from 13 - 19 minutes. Blood concentrations drop rapidly after complete absorption. The half-life of the salicylate ranges between 3.5 and 4.5 hours .

That half life of clopidogrel is approximately 6 hours following a 75mg oral dose while the half life of the active metabolite is approximately 30 minutes.

Clearance

The clearance rate of acetylsalicylic acid is extremely variable, depending on several factors . Dosage adjustments may be required in patients with renal impairment . The extended-release tablet should not be administered to patients with eGFR of less than 10 mL/min .

The clearance of a 75mg oral dose was 18,960±15,890L/h and for a 300mg oral dose was 16,980±10,410L/h.

Elimination Route

Excretion of salicylates occurs mainly through the kidney, by the processes of glomerular filtration and tubular excretion, in the form of free salicylic acid, salicyluric acid, and, additionally, phenolic and acyl glucuronides .

Salicylate can be found in the urine soon after administration, however, the entire dose takes about 48 hours to be completely eliminated. The rate of salicylate is often variable, ranging from 10% to 85% in the urine, and heavily depends on urinary pH. Acidic urine generally aids in reabsorption of salicylate by the renal tubules, while alkaline urine increases excretion .

After the administration of a typical 325mg dose, the elimination of ASA is found to follow first order kinetics in a linear fashion. At high concentrations, the elimination half-life increases .

An oral dose of radiolabelled clopidogrel is excreted 50% in the urine and 46% in the feces over 5 days. The remainder of clopidogrel is irreversibly bound to platelets for their lifetime, or approximately 8-11 days.

Pregnancy & Breastfeeding use

Pregnancy: Adverse effects are increased in the mother and the fetus following chronic ingestion of Aspirin. Because of possible adverse effects on the neonate and the potential for increased maternal blood loss, Clopidogrel + Aspirin should be avoided during the last three months of pregnancy.

Lactation: Clopidogrel + Aspirin should be avoided in nursing mothers because of the possible risk of developing Reye\'s syndrome. Regular use of high doses of Aspirin could impair platelet function and produce hypoprothrombinemia in infants if neonatal vitamin K levels are low.

Contraindication

Hypersensitivity to Clopidogrel & Aspirin. Hypo-prothrombinaemia, haemophilia and active peptic ulceration, active pathological bleeding such as peptic ulcer or intracranial haemorrhage.

Special Warning

It should not be given to children, particularly those under 12 years, unless the expected benefits outweight the possible risks. Aspirin may be a contributory factor in the causation of Reye’s syndrome in some children.

Acute Overdose

Overdosage produces dizziness, tinnitus, sweating, nausea and vomiting, confusion and hyperventilation. Gross overdosage may lead to CNS depression with coma, cardiovascular collapse and respiratory depression. If overdosage is suspected, the patient should be kept under observation for at least 24 hours, as symptoms and salicylate blood levels may not become apparent for several hours. Treatment of overdosage consists of gastric lavage and forced alkaline diuresis. Haemodialysis may be necessary in severe cases.

In the event of over dosage no adverse effects were reported and no therapy was substituted.

Symptoms: Prolonged bleeding time and subsequent bleeding complications.

Management: May restore clotting ability with platelet transfusion.

Storage Condition

Store in a cool and dry place, protected from light.

Innovators Monograph

You find simplified version here Opigrel A