Asasantin Retard Capsules
SUMMARY OF PRODUCT CHARACTERISTICS
1 NAME OF THE MEDICINAL PRODUCT
ASASANTIN® Retard
2 QUALITATIVE AND QUANTITATIVE COMPOSITION
Each capsule contains dipyridamole 200 mg and aspirin 25 mg.
3 PHARMACEUTICAL FORM
Capsule containing aspirin in standard release form and dipyridamole in modified release form.
Capsules consisting of a red cap and an ivory body imprinted with the company logo and the figures “01A”.
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Secondary prevention of ischaemic stroke and transient ischaemic attacks.
4.2 Posology and method of administration
For oral administration.
Adults, including the elderly
The recommended dose is one capsule twice daily, usually one in the morning and one in the evening preferably with meals.
The capsules should be swallowed whole without chewing together with a glass of water.
Children
ASASANTIN Retard is not indicated for use in children and young people.
Do not give to children aged under 16 years, unless specifically indicated (e.g. for Kawasaki’s disease)
Alternative regimen in case of intolerable headaches
In the event of intolerable headaches during treatment initiation, switch to one capsule at bedtime and low-dose acetylsalicylic acid (ASA) in the morning. Because there are no outcome data with this regimen and headaches become less of a problem as treatment continues, patients should return to the usual regimen as soon as possible, usually within one week.
4.3 Contraindications
Hypersensitivity to any component of the product or salicylates.
Patients with active gastric or duodenal ulcers or with bleeding disorders. Patients in the last trimester of pregnancy.
In case of rare hereditary conditions that may be incompatible with an excipient of the product (please refer to “special warnings and precautions”) the use of the product is contraindicated.
4.4 Special warnings and precautions for use
Bleeding disorders
Due to the risk of bleeding, as with other antiplatelet agents, ASASANTIN should be used with caution in patients at increased bleeding risk and patients should be followed carefully for any signs of bleeding, including occult bleeding (see section 4.5).
Caution should be advised in patients receiving concomitant medication which may increase the risk of bleeding, such as anticoagulants, anti-platelet agents, selective serotonin reuptake inhibitors (SSRIs), or anagrelide (see section 4.5).
Cardiovascular disorders
Among other properties dipyridamole acts as a vasodilator. Dipyridamole should be used with caution in patients with severe coronary artery disease, including unstable angina and/or recent myocardial infarction, left ventricular outflow obstruction, or haemodynamic instability (e.g. decompensated heart failure).
The dose of aspirin in ASASANTIN Retard has not been studied in secondary prevention of myocardial infarction.
Myasthenia gravis
In patients with myasthenia gravis readjustment of therapy may be necessary after changes in dipyridamole dosage (see section 4.5).
Biliary disorders
A small number of cases have been reported in which unconjugated dipyridamole was shown to be incorporated into gallstones to a variable extent (up to 70% by dry weight of stone). These patients were all elderly, had evidence of ascending cholangitis and had been treated with oral dipyridamole for a number of years. There is no evidence that dipyridamole was the initiating factor in causing gallstones to form in these patients. It is possible that bacterial deglucuronidation of conjugated dipyridamole in bile may be the mechanism responsible for the presence of dipyridamole in gallstones.
Headache or migraine-like headache
Headache or migraine-like headache which may occur especially at the beginning of ASASANTIN therapy should not be treated with analgesic doses of acetylsalicylic acid (see section 4.2).
Hypersensitivity
In addition, caution is advised in patients hypersensitive to non-steroidal antiinflammatory drugs (NSAIDs).
Aspirin (Acetvlsalicvlic Acid) related warnings
Due to the aspirin component, ASASANTIN Retard should be used in caution in patients with asthma, allergic rhinitis, nasal polyps, chronic or recurring gastric or duodenal complaints, impaired renal (avoid if severe) or hepatic function (see section 5.2) or glucose-6-phosphate dehydrogenase deficiency.
Children and adolescents
ASASANTIN Retard is not indicated for use in children and young people. There is a possible association between aspirin and Reye’s syndrome when given to children. Reye’s syndrome is a very rare disease, which affects the brain and liver, and can be fatal. For this reason aspirin should not be given to children aged under 16 years unless specifically indicated (e.g. for Kawasaki’s disease).
Stress testing with intravenous dipyridamole
Patients being treated with regular oral doses of ASASANTIN Retard should not receive additional intravenous dipyridamole. Clinical experience suggests that patients being treated with oral dipyridamole who also require pharmacological stress testing with intravenous dipyridamole, should discontinue drugs containing oral dipyridamole twenty-four hours prior to being treated with intravenous dipyridamole.
Excipients
One capsule contains 53 mg lactose and 11.32 mg sucrose, resulting in 106 mg of lactose and 22.64 mg sucrose per maximum recommended daily dose. Patients with rare hereditary problems of fructose intolerance, galactose intolerance, the Lapp lactase deficiency, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicine.
4.5 Interaction with other medicinal products and other forms of interaction
NSAIDs/Corticosteroids/Alcohol
Gastrointestinal side effects may increase when aspirin is administered concomitantly with NSAIDs, corticosteroids or chronic alcohol use.
There is some experimental evidence that ibuprofen interferes with aspirin induced inhibition of platelet cyclo-oxygenase. This interaction could reduce the beneficial cardiovascular effects of aspirin, however the evidence for this is not conclusive. Further, in view of the known increased risk of gastrointestinal toxicity associated with NSAID and aspirin co-medication, this combination should be avoided wherever possible. When such a combination is necessary the balance of gastrointestinal and cardiovascular risks should be considered.
Drugs affecting coagulation
When dipyridamole is used in combination with other substances impacting coagulation such as anticoagulants and antiplatelet agents the safety profile for these medications must be observed.
Aspirin has been shown, when given with anticoagulants (e.g. coumarin derivatives and heparin), antiplatelet drugs (e.g. clopidogrel, ticlopidine), selective serotonin reuptake inhibitors (SSRIs), or anagrelide to increase the risk of bleeding. The addition of dipyridamole to aspirin does not increase the incidence of bleeding events.
When dipyridamole was administered concomitantly with warfarin, bleeding was no greater in frequency or severity than that observed when warfarin was administered alone.
Anticonvulsants
Aspirin may enhance the effect of valproic acid and phenytoin with possible increased risk of side effects.
Adenosine
Dipyridamole increases the plasma levels and cardiovascular effects of adenosine. Adjustment of adenosine dosage should therefore be considered if use with dipyridamole is unavoidable.
Antihypertensives
Dipyridamole may increase the hypotensive effect of drugs, which reduce blood pressure.
Cholinesterase inhibitors
Dipyridamole may counteract the anticholinesterase effect of cholinesterase inhibitors thereby potentially aggravating myasthenia gravis (see section 4.4).
Hypoglycaemics/Methotrexate
The effect of hypoglycaemic agents and the toxicity of methotrexate may be increased by the concomitant administration of aspirin.
Spironolactone/Uricosuric agents
Aspirin may decrease the natriuretic effect of spironolactone and inhibit the effect of uricosuric agents (e.g. probenecid, sulfinpyrazone).
4.6 Fertility, pregnancy and lactation
Pregnancy
There is inadequate evidence of the safety in human pregnancy regarding dipyridamole and aspirin at low dose (see section 5.3).
Animal studies performed with the drug combination revealed no increased teratogenic risk over the individual components alone. Studies covering the peri-postnatal period have not been performed with the combination (see section 5.3).
ASASANTIN Retard should only be administered during first and second trimester of pregnancy when the potential benefits for the mother outweigh the possible risks for the foetus.
ASASANTIN Retard is contraindicated in the third trimester of pregnancy.
Lactation
Dipyridamole and salicylates are excreted in breast milk (see section 5.2). ASASANTIN Retard should only be used in breast-feeding women when the potential benefits for the mother outweigh the possible risks for the newborn.
Fertility
No studies on the effects of human fertility have been conducted. Fertility studies were only performed with the individual components. No impairment of fertility was observed with dipyridamole. Acetylsalicylic acid can inhibit ovulation in rats (see section 5.3).
4.7. Effects on ability to drive and use machines
No studies on the effect on the ability to drive and use machines have been performed. However, patients should be advised that symptoms such as dizziness and confusional state have been reported in clinical trials. If patients experience such symptoms, they should avoid potentially hazardous tasks such as driving or operating machinery.
4.8 Undesirable effects
Summary of the safety profile
Two large scale trials (ESPS-2, PRoFESS) enrolling a total of 26,934 patients (thereof 11,831 patients were allocated to ASASANTIN) were used to define the safety profile of ASASANTIN. These data are supplemented with the extensive ASASANTIN Retard post-marketing experience.
The most frequently reported adverse reactions are headache, dizziness and gastrointestinal events such as dyspepsia, diarrhoea, nausea and abdominal pain. Most important serious adverse reactions associated with ASASANTIN Retard were bleeding events.
Table of side effects
The following adverse reactions have been reported during use of ASASANTIN Retard in ESPS-2 and PRoFESS and from spontaneous reporting. The following terms are used to rank the ADRs by frequency: very common (> 1/10); common (> 1/100 to < 1/10); uncommon (> 1/1,000 to < 1/100); rare (> 1/10,000 to < 1/1,000); very rare (< 1/10,000) and not known (cannot be estimated from the available data).
|
MedDRA System Organ Class |
Dipyridamole and Acetylsalicylic acid Adverse reactions |
Frequency |
|
Blood and |
Anaemia, |
Common |
|
lymphatic |
Thrombocytopenia, |
Rare |
|
system |
Iron deficiency anaemia (due to |
Rare |
|
disorders |
occult gastrointestinal bleeding) | |
|
Disseminated intravascular coagulation2, Coagulopathy2 |
Not known* | |
|
Cardiac |
Worsening of symptoms of coronary |
Common |
|
disorders |
artery disease, | |
|
Syncope, |
Common | |
|
Tachycardia |
Uncommon |
|
MedDRA System Organ Class |
Dipyridamole and Acetylsalicylic acid Adverse reactions |
Frequency |
|
Arrhythmia2 |
Not known* | |
|
Ear and |
Tinnitus2, |
Not known* |
|
labyrinth disorders |
Deafness2 | |
|
Eye disorders |
Eye haemorrhage |
Uncommon |
|
MedDRA System Organ Class |
Dipyridamole and Acetylsalicylic acid Adverse reactions |
Frequency |
|
Gastrointestinal disorders |
Vomiting, Nausea, Diarrhoea, Dyspepsia, Abdominal pain, Gastrointestinal haemorrhage, Gastric ulcer, Duodenal ulcer, Gastritis erosive |
Common Very Common Very Common Very Common Very Common Common Uncommon Rare |
|
Gastric ulcer perforation2, Duodenal ulcer perforation2, Melaena2, Haematemesis2, Pancreatitis2 |
Not known* | |
|
General disorders and administration site conditions |
Pyrexia2, Hypothermia2 |
Not known* |
|
Hepatobiliary disorders |
Dipyridamole has been shown to be incorporated into gallstones1 |
Not known* |
|
Hepatitis2, Reye’s syndrome2 |
Not known* | |
|
Immune system disorders |
Hypersensitivity reactions (including rash, urticaria, severe bronchospasm and angio-oedema) |
Common |
|
Anaphylactic reactions (especially in patients with asthma)2 |
Not known* | |
|
Injury, poisoning and procedural complications |
Post-procedural haemorrhage, Procedural haemorrhage |
Not known* Not known* |
|
Investigations |
Bleeding time prolonged |
Not known* |
|
Liver function test abnormal2, Blood uric acid increased (may lead to gout attacks)2, Prothrombin time prolonged2 |
Not known* | |
|
Metabolism and nutrition disorders |
Hypoglycaemia (children)2, Hyperglycaemia2, Thirst2, Dehydration2, Hyperkaleamia2, Metabolic acidosis2, Respiratory alkalosis2 |
Not known* |
|
Musculoskeleta l, connective tissue and bone disorder |
Myalgia |
Common |
|
Rhabdomyolysis2 |
Not known* | |
|
Nervous system disorders |
Haemorrhage intracranial, Migraine-like headache (especially at the beginning of treatment), Dizziness, Headache |
Common Common Very Common Very Common |
|
MedDRA System Organ Class |
Dipyridamole and Acetylsalicylic acid Adverse reactions |
Frequency |
|
Agitation2, Brain oedema2, Lethargy2, Convulsion2 |
Not known* |
|
MedDRA System Organ Class |
Dipyridamole and Acetylsalicylic acid Adverse reactions |
Frequency |
|
Pregnancy, puerperium and perinatal conditions |
Prolonged pregnancy2, Prolonged labour2, Small for dates baby2, Stillbirth2, Haemorrhage in pregnancy2, Postpartum haemorrhage2 |
Not known* |
|
Psychiatric disorders |
Confusional state2 |
Not known* |
|
Renal and urinary disorders |
Renal failure2, Nephritis Interstitial2, Renal papillary necrosis2, Proteinuria2 |
Not known* |
|
Respiratory, thoracic and mediastinal disorders |
Epistaxis |
Common |
|
Dyspnoea2 Gingival bleeding2, Laryngeal oedema2, Hyperventilation2, Pulmonary oedema2, Tachypnoea2 |
Not known* | |
|
Skin and subcutaneous tissue disorders |
Skin haemorrhages (including contusion, ecchymosis and haematoma) |
Not known* |
|
Erythema exsudativum multiforme2 |
Not known* | |
|
Vascular disorders |
Hypotension, Hot flush |
Uncommon Uncommon |
1 Identified adverse reactions of Dipyridamole monotherapy
2 Identified adverse reactions of Acetylsalicylic acid monotherapy
*These ADRs were not reported in clinical trials, therefore a frequency could not be calculated.
Description of selected side effects
The most important serious adverse reactions associated with ASASANTIN Retard were bleeding events. Data from ESPS-2 and PRoFESS trials for bleeding events including major bleeding were evaluated. Bleeding events categorized as any bleeding, major bleeding, intracranial bleeding and gastrointestinal bleeding:
In the controlled ESPS-2 trial, 1650 patients were treated in the ASASANTIN group (100%) and 1649 in the placebo group (100%). The mean duration of treatment was 1.4 years. The overall incidence of bleeding was 8.7% in the ASASANTIN group and 4.5% in the placebo group. The incidence of major bleeding was 1.6% and 0.4% respectively. The incidence of intracranial bleeding was 0.6% and 0.4% respectively, whilst the incidence of gastrointestinal bleeding was 4.3% and 2.6% respectively.
In the PRoFESS trial, a total of 10,055 patients were treated in the ASASANTIN group (100%). The mean duration of treatment was 1.9 years. The overall incidence of bleeding was 5.3%. The incidence of major bleeding was 3.3%. The incidence of intracranial bleeding was 1.2% (including intraocular bleeding (0.2%)), whilst the incidence of gastrointestinal bleeding was 1.9%.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit / risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard
4.9. Overdose
Symptoms
Because of the dose ratio of dipyridamole to aspirin, overdosage is likely to be dominated by signs and symptoms of dipyridamole overdose.
Due to the low number of observations, experience with dipyridamole overdose is limited.
Symptoms such as a warm feeling, flushes, sweating, accelerated pulse, restlessness, feeling of weakness, dizziness, and anginal complaints can be expected. A drop in blood pressure and tachycardia might be observed.
Salicylate poisoning is usually associated with plasma concentrations >350 mg/L (2.5 mmol/L). Most adult deaths occur in patients whose concentrations exceed 700 mg/L (5.1 mmol/L). Single doses less than 100 mg/kg are unlikely to cause serious poisoning.
Symptoms of salicylate overdose commonly include vomiting, dehydration, tinnitus, vertigo, deafness, sweating, warm extremities with bounding pulses, increased respiratory rate and hyperventilation. Some degree of acid-base disturbance is present in most cases.
A mixed respiratory alkalosis and metabolic acidosis with normal or high arterial pH (normal or reduced hydrogen ion concentration) is usual in adults and children over the age of four years. In children aged four years or less, a dominant metabolic acidosis with low arterial pH (raised hydrogen ion concentration) is common.
Acidosis may increase salicylate transfer across the blood brain barrier.
Uncommon features of salicylate poisoning include haematemesis, hyperpyrexia, hypoglycaemia, hypokalaemia, thrombocytopaenia, increased INR/PTR, intravascular coagulation, renal failure and non-cardiac pulmonary oedema. Central nervous system features including confusion, disorientation, coma and convulsions are less common in adults than in children.
Dizziness and tinnitus can, particularly in elderly patients, be symptoms of overdose.
Therapy
Administration of xanthine derivatives (e.g. aminophylline) may reverse the haemodynamic effects of dipyridamole overdose. Due to its wide distribution to tissues and its predominantly hepatic elimination, dipyridamole is not likely to be accessible to enhanced removal procedures.
In the case of salicylate poisoning activated charcoal should be given to adults who present within one hour of ingestion of more than 250 mg/kg. The plasma salicylate concentration should be measured, although the severity of poisoning cannot be determined from this alone and the clinical and biochemical features must be taken into account. Elimination is increased by urinary alkalinisation, which is achieved by the administration of 1.26% sodium bicarbonate. The urine pH should be monitored. Correct metabolic acidosis with intravenous 8.4% sodium bicarbonate (first check serum potassium). Forced diuresis should not be used since it does not enhance salicylate excretion and may cause pulmonary oedema.
Haemodialysis is the treatment of choice for severe poisoning and should be considered in patients with plasma salicylate concentrations > 700 mg/L (5.1 mmol/L), or lower concentrations associated with severe clinical or metabolic features. Patients under ten years or over 70 have increased risk of salicylate toxicity and may require dialysis at an earlier stage.
5. PHARMACOLOGICAL PROPERTIES
5.1. Pharmacodynamic properties
The antithrombotic action of the Acetylsalicylic acid (aspirin)/dipyridamole combination is based on the different biochemical mechanisms involved. Acetylsalicylic acid (aspirin) inactivates irreversibly the enzyme cyclo-oxygenase in platelets thus preventing the production of thromboxane A2, a powerful inducer of platelet aggregation and vasoconstriction.
Dipyridamole inhibits the uptake of adenosine into erythrocytes, platelets and endothelial cells in vitro and in vivo; the inhibition amounts to approximately 80% at maximum and occurs dose-dependently at therapeutic concentrations (0.5 - 2 mcg/ml). Consequently, there is an increased concentration of adenosine locally to act on the platelet A2-receptor, stimulating platelet adenylate cyclase, thereby increasing
platelet cAMP levels.
Thus, platelet aggregation in response to various stimuli such as platelet activating factor (PAF), collagen and adenosine diphosphate (ADP) is inhibited. Reduced platelet aggregation reduces platelet consumption towards normal levels. In addition, adenosine has a vasodilator effect and this is one of the mechanisms by which dipyridamole produces vasodilation.
Dipyridamole has also been shown in stroke patients to reduce the density of prothrombotic surface proteins (PAR-1: Thrombin receptor) on platelets as well as to reduce levels of c-reactive protein (CRP) and von Willebrand Factor (vWF). In-vitro investigations have shown that dipyridamole selectively inhibits inflammatory cytokines (MCP-1 and MMP-9) arising from platelet-monocyte interaction. Dipyridamole inhibits phosphodiesterase (PDE) in various tissues.
Whilst the inhibition of cAMP-PDE is weak, therapeutic levels of dipyridamole inhibit cGMP-PDE, thereby augmenting the increase in cGMP produced by EDRF (endothelium-derived relaxing factor, identified as nitric oxide (NO)).
Dipyridamole increases the release of t-PA from microvascular endothelial cells and was shown to amplify the antithrombotic properties of endothelial cells on thrombus formation on adjacent subendothelial matrix in a dose dependent manner. Dipyridamole is a potent radical scavenger for oxy- and peroxy-radicals.
Dipyridamole also stimulates the biosynthesis and release of prostacyclin by the endothelium and reduces the thrombogenicity of subendothelial structures by increasing the concentration of the protective mediator 13-HODE (13-hydroxyoctadecadienic acid).
Whereas acetylsalicylic acid (aspirin) inhibits only platelet aggregation, dipyridamole in addition inhibits platelet activation and adhesion. Therefore an additional benefit from combining both drugs can be expected
Clinical Trials :
ASASANTIN Retard® was studied in a double-blind, placebo-controlled, 24-month study (European Stroke Prevention Study 2, ESPS2) in which 6602 patients had an ischemic stroke or transient ischemic attack (TIA) within three months prior to entry. Patients were randomized to one of four treatment groups: ASASANTIN Retard (ASA /extended-release dipyridamole) 25 mg/200 mg; extended-release dipyridamole (ER-DP) 200 mg alone; ASA 25 mg alone; or placebo. Patients received one capsule twice daily (morning and evening). Efficacy assessments included analyses of stroke (fatal or nonfatal) and death (from all causes) as confirmed by a blinded morbidity and mortality assessment group. In ESPS-2 ASASANTIN Retard reduced the risk of stroke by 23.1 % compared to ASA 50 mg/day alone (p =0.006) and reduced the risk of stroke by 24.7% compared to extended-release dipyridamole 400 mg/day alone (p = 0.002). ASASANTIN Retard reduced the risk of stroke by 37% compared to placebo (p <0.001).
The results of the ESPS-2 study are supported by the European/Australasian Stroke Prevention in Reversible Ischaemia Trial (ESPRIT) study [112] which studied a combination treatment of diypridamole 400 mg daily (83% of patients treated with the extended-release dipyridamole formulation) and ASA 30-325 mg daily. A total of 2739 patients after ischaemic stroke of arterial origin were enrolled in the ASA-alone (n = 1376) and combination ASA plus dipyridamole (n = 1363) arm. The primary outcome event was the composite of death from all vascular causes, non-fatal stroke, non-fatal myocardial infarction (MI), or major bleeding complications. Patients in the ASA plus dipyridamole group showed a 20% risk reduction (p<0.05) for the primary composite endpoint compared with those in the ASA alone group (12.7% vs. 15.7%; hazard ratio [HR] 0.80, 95% CI 0.66-0.98).
The PRoFESS (PRevention Regimen For Effectively avoiding Second Strokes) study was a randomized, parallel group, international, double-blind, double-dummy, active and placebo controlled, 2x2 factorial study to compare ASASANTIN with clopidogrel, and telmisartan with matching placebo in the prevention of stroke in patients who had previously experienced an ischaemic stroke of noncardioembolic origin. A total of 20,332 patients were randomized to ASASANTIN (n= 10,181) or clopidogrel (n = 10,151), both given on a background of standard treatment. The primary endpoint was the time to first recurrent stroke of any type.
The incidence of the primary endpoint was similar in both treatment groups (9.0% for ASASANTIN vs. 8.8% for clopidogrel; HR 1.01, 95 % CI 0.92-1.11). No significant difference between the ASASANTIN and clopidogrel treatment groups were detected for several other important pre-specified endpoints, including the composite of recurrent stroke, myocardial infarction, or death due to vascular causes (13.1% in both treatment groups; HR 0.99, 95 % CI 0.92-1.07) and the composite of recurrent stroke or major haemorrhagic event (11.7% for ASASANTIN vs. 11.4% for clopidogrel; HR 1.03, 95 % CI 0.95-1.11). The functional neurological outcome 3 months post recurrent stroke was assessed by the Modified Rankin Scale (MRS) and no significant difference in the distribution of the MRS between ASASANTIN and clopidogrel was observed (p = 0.3073 by Cochran-Armitage test for linear trend).
More patients randomised to ASA+ER-DP (4.1%) than to clopidogrel (3.6%) experienced a major haemorrhagic event (HR = 1.15; 95% CI 1.00, 1.32; p = 0.0571). The difference between the treatment groups was mainly due to the higher incidence of non-life threatening major haemorrhagic events in the ASA+ER-DP group (2.9%) than in the clopidogrel group (2.5%) while the incidences of life threatening haemorrhagic events were similar in both groups (128 patients vs. 116 patients). The overall incidence of intracranial haemorrhage was higher in the ASA+ER-DP group (1.4%) than in the clopidogrel group (1.0%) resulting in a HR of 1.42 (95% CI 1.11, 1.83) with a p-value of 0.0062. The difference between the treatment groups resulted mainly from the higher incidence of haemorrhagic strokes in the ASA+ER-DP group (0.9% vs. clopidogrel 0.5%).
5.2. Pharmacokinetic properties
There is no noteworthy pharmacokinetic interaction between the extended release pellets of dipyridamole and acetylsalicylic acid (aspirin). Therefore pharmacokinetics of ASASANTIN Retard is reflected by the pharmacokinetics of the individual components.
Dipyridamole
(Most pharmacokinetic data refer to healthy volunteers.)
With dipyridamole, there is dose linearity for all doses used in therapy.
For long-term treatment dipyridamole modified release capsules, formulated as pellets were developed. The pH dependent solubility of dipyridamole which prevents dissolution in the lower parts of the gastro-intestinal tract (where sustained release preparations must still release the active principle) was overcome by combination with tartaric acid. Retardation is achieved by a diffusion membrane, which is sprayed onto the pellets.
Various kinetic studies at steady state showed, that all pharmacokinetic parameters which are appropriate to characterise the pharmacokinetic properties of modified release preparations are either equivalent or somewhat improved with dipyridamole modified release capsules given b.i.d. compared to dipyridamole tablets administered t.d.s./q.d.s.: Bioavailability is slightly greater, peak concentrations are similar, trough concentrations are considerably higher and peak trough fluctuation is reduced.
Absorption
The absolute bioavailability is about 70%. As first pass removes approx. 1/3 of the dose administered, near to complete absorption of dipyridamole following administration of acetylsalicylic acid (aspirin) modified release capsules can be assumed.
Peak plasma concentrations of dipyridamole following a daily dose of 400 mg acetylsalicylic acid (aspirin) (given as 200 mg b.i.d) are reached about 2 - 3 hours after administration. There is no relevant effect of food on the pharmacokinetics of dipyridamole in acetylsalicylic acid (aspirin) modified release capsules.
Distribution
Owing to its high lipophilicity, log P 3.92 (n-octanol/0.1n, NaOH), dipyridamole distributes to many organs.
In animals, dipyridamole is distributed preferentially to the liver, then to the lungs, kidneys, spleen and heart. Although, the preferred distribution of dipyridamole has not been established in humans, its major presence in human liver, kidney and heart after oral administration has been extensively reported.
The apparent volume of distribution of the central compartment (Vc) is about 5 l (similar to plasma volume). The apparent volume of distribution at steady state is about 100 l, reflecting distribution to various compartments.
The drug does not cross the blood-brain barrier to a significant extent.
The protein binding of Dipyridamole is about 97-99%, primarily it is bound to alpha 1-acid glycoprotein and albumin.
In virtue of the presence of BCPR, an active drug uptake transporter in the human placenta, dipyridamole could be transferred into the foetal direction.
Metabolism
Metabolism of dipyridamole occurs in the liver. Dipyridamole is metabolized primarily by conjugation with glucuronic acid to form mainly a monoglucuronide and only small amounts of diglucuronide. In plasma about 80% of the total amount is present as parent compound, and 20% of the total amount as monoglucuronide. The pharmacodynamic activity of dipyridamole glucuronides is considerably lower than that of dipyridamole.
Elimination
The dominant half-life with oral administration is about 40 minutes as it is the case with i.v. administration.
Renal excretion of parent compound is negligible (< 0.5%). Urinary excretion of the glucuronide metabolite is low (5%), the metabolites are mostly (about 95%) excreted via the bile into the faeces, with some evidence of entero-hepatic recirculation.
Total clearance is approximately 250 ml/min and mean residence time is about 11 hours (resulting from an intrinsic MRT of about 6.4 h and a mean time of absorption of 4.6 h).
As with i.v. administration a prolonged terminal elimination half-life of approximately 13 hours is observed.
This terminal elimination phase is of relatively minor importance in that it represents a small proportion of the total AUC, as evidenced by the fact that steady state is achieved within 2 days with b.i.d. regimens of modified release capsules. There is no significant accumulation of the drug with repeated dosing.
Kinetics in elderly
Dipyridamole plasma concentrations (determined as AUC) in elderly subjects (> 65 years) were about 50% higher for tablet treatment and about 30% higher with intake of ASASANTIN Retard modified release capsules than in young (<55 years) subjects. The difference is caused mainly by reduced clearance; absorption appears to be similar.
Similar increases in plasma concentrations in elderly patients were observed in the ESPS2 study for PERSANTIN® modified release capsules as well as for ASASANTIN Retard.
Kinetics in patients with renal impairment
Since renal excretion is very low (5%), no change in pharmacokinetics is to be expected in cases of renal insufficiency. In the ESPS2 trial, in patients with creatinine clearances ranging from about 15 mL/min to >100 mL/min, no changes were observed in the pharmacokinetics of dipyridamole or its glucuronide metabolite if data were corrected for differences in age.
Kinetics in patients with hepatic impairment
Patients with hepatic insufficiency show no change in plasma concentrations of dipyridamole, but an increase of (pharmacodynamically low active) glucuronides. It is suggested to dose dipyridamole without restriction as long as there is no clinical evidence of liver failure.
Acetylsalicylic acid (aspirin)
Absorption
After oral administration acetylsalicylic acid (aspirin) is rapidly and completely absorbed in the stomach and intestine. Approximately 30% of the dose of acetylsalicylic acid (aspirin) is hydrolyzed presystemically to salicylic acid.
Maximum plasma concentrations after a daily dose of 50 mg acetylsalicylic acid from ASASANTIN Retard (given as 25 mg twice daily) are attained after 30 minutes of each dose, and peak plasma concentration at steady state amounted to approximately 360 ng/mL for acetylsalicylic acid (aspirin); maximum plasma concentrations of salicylic acid are achieved after 60-90 minutes and amount to approximately 1100 ng/ml. There is no relevant effect of food on the pharmacodynamics of acetylsalicylic acid in ASASANTIN Retard.
Distribution
Acetylsalicylic acid (aspirin) is rapidly converted to salicylate but is the predominant form of the drug in the plasma during the first 20 minutes following oral administration.
Plasma acetylsalicylic acid (aspirin) concentrations decline rapidly with a half-life of approx. 15 minutes. Its major metabolite, salicylic acid, is highly bound to plasma proteins, and its binding is concentration-dependent (nonlinear). At low concentrations (<100 pg/mL), approximately 90% of salicylic acid is bound to albumin. Salicylates are widely distributed to all tissues and fluids in the body, including the central nervous system, breast milk, and fetal tissues.
Metabolism
Acetylsalicylic acid (aspirin) is metabolised rapidly by non-specific esterases to salicylic acid. Salicylic acid is metabolised to salicyluric acid, salicyl phenolic glucuronide, salicylic acyl glucuronide, and to a minor extent to gentisic acid and gentisuric acid. The formation of the major metabolites salicyluric acid and salicylic phenolic glucuronide is easily saturated and follows Michaelis-Menten kinetics; the other metabolic routes are first-order processes.
Elimination
Acetylsalicylic acid (aspirin) has an elimination half-life of elimination of 15-20 minutes in plasma; the major metabolite salicylic acid has a half-life of elimination of 2-3 hours at low doses (e.g. 325 mg), which may rise to 30 hours at higher doses because of nonlinearity in metabolism and plasma protein binding.
More than 90% of acetylsalicylic acid (aspirin) is excreted as metabolites via the kidneys. The fraction of salicylic acid excreted unchanged in the urine increases with increasing dose and the renal clearance of total salicylate also increases with increasing urinary pH.
Kinetics in patients with renal impairment
Renal dysfunction: acetylsalicylic acid (aspirin) is to be avoided in patients with severe renal failure (glomerular filtration rate less than 10 mL/min). An increase in total plasma concentrations and in the unbound fraction of salicylic acid has been reported.
Kinetics in patients with hepatic impairment
Hepatic dysfunction: acetylsalicylic acid is to be avoided in patients with severe hepatic insufficiency. An increase in the unbound fraction of salicylic acid has been reported.
5.3 Preclinical safety data
Dipyridamole and aspirin separately have been extensively investigated in animal models and no clinically significant findings have been observed at doses equivalent to therapeutic doses in humans. Toxicokinetic evaluations were not included in these studies.
Studies with the drug combination dipyridamole/aspirin in a ratio of 1:4 revealed additive, but no potentiating toxic effects. A single dose study in rats using dipyridamole/aspirin in a ratio of 1:0.125 gave comparable results to studies with the 1:4 combination.
Fertility studies were only performed with the individual components. No impairment of fertility was observed with dipyridamole. Acetylsalicylic acid can inhibit ovulation in rats.
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
Tartaric acid Povidone
Methacrylic acid-methyl methacrylate copolymer (1:2)
Talc
Acacia
Hypromellose phthalate Hypromellose Triacetin Dimethicone 350 Stearic acid Lactose
Aluminium stearate Colloidal silica Maize starch
Microcrystalline cellulose Sucrose
Titanium dioxide; E171
Capsule Shells:
Gelatin
Titanium dioxide; E171
Red and yellow iron oxides; E172
Printing Ink:
Shellac Ethyl alcohol Isopropyl alcohol Propylene glycol N-butyl alcohol Ammonium hydroxide Potassium hydroxide Purified water Red iron oxide; E172
6.2 Incompatibilities
None stated.
6.3 Shelf life
Unopened: 36 months
In-use: Discard any capsules remaining 6 weeks after first opening.
6.4. Special precautions for storage
Store in the original container in order to protect from moisture. Keep the bottle tightly closed.
Store below 30°C.
6.5 Nature and contents of container
White polypropylene bottles with child resistant multipart polypropylene/polyethylene screw cap containing a desiccant made from silica gel/molecular sieves. Pack size of 60 capsules.
6.6 Special precautions for disposal
None stated.
7 MARKETING AUTHORISATION HOLDER
Boehringer Ingelheim limited
Ellesfield Avenue
Bracknell
Berkshire
RG12 8YS
England
8 MARKETING AUTHORISATION NUMBER(S)
PL 00015/0224
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
Date of First Authorisation: 12 May 1998 Date of Last Renewal: 22 December 2003
10 DATE OF REVISION OF THE TEXT
05/08/2015