SECURON SR Modified-release tablet Ref.[7143] Active ingredients: Verapamil

Since verapamil is extensively metabolised in the liver, careful dose titration is required in patients with liver disease. Although the pharmacokinetics of verapamil in patients with renal impairment are not affected, caution should be exercised and careful patient monitoring is recommended. Verapamil is not removed during dialysis.

Verapamil may affect impulse conduction and should therefore be used with caution in patients with bradycardia or first degree AV block. Verapamil may affect left ventricular contractility; this effect is small and normally not important but cardiac failure may be precipitated or aggravated. In patients with incipient cardiac failure, therefore, verapamil should be given only after such cardiac failure has been controlled with appropriate therapy, e.g. digitalis.

When treating hypertension with verapamil, monitoring of the patient’s blood pressure at regular intervals is required.

Caution should be exercised in treatment with HMG CoA reductase inhibitors (e.g. simvastatin, atorvastatin or lovastatin) for patients taking verapamil. These patients should be started at the lowest possible dose of verapamil and titrated upwards. If verapamil treatment is to be added to patients already taking an HMG CoA reductase inhibitor (e.g. simvastatin, atorvastatin or lovastatin), refer to advice in the respective statin product information.

Use with caution in the presence of diseases in which neuromuscular transmission is affected (myasthenia gravis, Lambert-Eaton syndrome, advanced Duchenne muscular dystrophy).

In vitro metabolic studies indicate that verapamil hydrochloride is metabolized by cytochrome P450 CYP3A4, CYP1A2, CYP2C8, CYP2C9 and CYP2C18. Verapamil has been shown to be an inhibitor of CYP3A4 enzymes and P-glycoprotein (P-gp). Clinically significant interactions have been reported with inhibitors of CYP3A4 causing elevation of plasma levels of verapamil hydrochloride while inducers of CYP3A4 have caused a lowering of plasma levels of verapamil hydrochloride, therefore, patients should be monitored for drug interactions.

The following are potential drug interactions associated with verapamil:

Acetylsalicylic acid:

Concomitant use of verapamil with aspirin may increase the risk of bleeding

Alcohol:

Increase in blood alcohol has been reported.

Alpha blockers:

Verapamil may increase the plasma concentrations of prazosin and terazosin which may have an additive hypotensive effect.

Antiarrhythmics:

Verapamil may slightly decrease the plasma clearance of flecainide whereas flecainide has no effect on the verapamil plasma clearance.

Verapamil may increase the plasma concentrations of quinidine. Pulmonary oedema may occur in patients with hypertrophic cardiomyopathy

The combination of verapamil and antiarrhythmic agents may lead to additive cardiovascular effects (e.g. AV block, bradycardia, hypotension, heart failure).

Anticonvulsants:

Verapamil may increase the plasma concentrations of carbamazepine. This may produce side effects such as diplopia, headache, ataxia or dizziness. Verapamil may also increase the plasma concentrations of phenytoin.

Antidepressants:

Verapamil may increase the plasma concentrations of imipramine.

Antidiabetics:

Verapamil may increase the plasma concentrations of glibenclamide (glyburide).

Antihypertensives, diuretics, vasodilators:

Potentiation of the hypotensive effect.

Anti-infectives:

Rifampicin may reduce the plasma concentrations of verapamil which may produce a reduced blood pressure lowering effect. Erythromycin, clarithromycin and telithromycin may increase the plasma concentrations of verapamil.

Antineoplastics:

Verapamil may increase the plasma concentrations of doxorubicin.

Barbiturates:

Phenobarbital may reduce the plasma concentrations of verapamil.

Benzodiazepines and other anxiolytics:

Verapamil may increase the plasma concentrations of buspirone and midazolam.

Beta blockers:

Verapamil may increase the plasma concentrations of metoprolol and propranolol which may lead to additive cardiovascular effects (e.g. AV block, bradycardia, hypotension, heart failure).

Intravenous beta-blockers should not be given to patients under treatment with verapamil.

Cardiac glycosides:

Verapamil may increase the plasma concentrations of digitoxin and digoxin. Verapamil has been shown to increase the serum concentration of digoxin and caution should be exercised with regard to digitalis toxicity. The digitalis level should be determined and the glycoside dose reduced, if required.

Colchicine:

Colchicine is a substrate for both CYP3A and the efflux transporter, P-glycoprotein (P-gp). Verapamil is known to inhibit CYP3A and P-gp. When verapamil and colchicine are administered together, inhibition of P-gp and/or CYP3A by verapamil may lead to increased exposure to colchicine. Combined use is not recommended.

H₂ Receptor antagonists:

Cimetidine may increase the plasma concentrations of verapamil.

HIV antiviral agents:

Due to the metabolic inhibitory potential of some of the HIV antiviral agents, such as ritonavir, plasma concentrations of verapamil may increase. Caution should be used or dose of verapamil may be decreased.

Immunosuppressants:

Verapamil may increase the plasma concentrations of ciclosporin, everolimus, sirolimus and tacrolimus.

Inhaled anaesthetics:

When used concomitantly, inhalation anaesthetics and calcium antagonists, such as verapamil hydrochloride, should each be titrated carefully to avoid additive cardiovascular effects (e.g. AV block, bradycardia, hypotension, heart failure).

Lipid lowering agents:

Verapamil may increase the plasma concentrations atorvastatin, lovastatin and simvastatin.

Treatment with HMG CoA reductase inhibitors (e.g., simvastatin, atorvastatin or lovastatin) in a patient taking verapamil should be started at the lowest possible dose and titrated upwards. If verapamil treatment is to be added to patients already taking an HMG CoA reductase inhibitor (e.g., simvastatin, atorvastatin or lovastatin), consider a reduction in the statin dose and retitrate against serum cholesterol concentrations.

Atorvastatin has been shown to increase verapamil levels. Although there is no direct in vivo clinical evidence, there is strong potential for verapamil to significantly affect atorvastatin pharmacokinetics in a similar manner to simvastatin or lovastatin. Consider using caution when atorvastatin and verapamil are concomitantly administered.

Fluvastatin, pravastatin and rosuvastatin are not metabolized by CYP3A4 and are less likely to interact with verapamil.

Lithium:

Serum levels of lithium may be reduced. However, there may be increased sensitivity to lithium causing enhanced neurotoxicity.

Neuromuscular blocking agents employed in anaesthesia:

The effects may be potentiated.

Serotonin receptor agonists:

Verapamil may increase the plasma concentrations of almotriptan.

Theophylline:

Verapamil may increase the plasma concentrations of theophylline.

Uricosurics:

Sulfinpyrazone may reduce the plasma concentrations of verapamil which may produce a reduced blood pressure lowering effect.

Anticoagulants:

When oral verapamil was co-administered with dabigatran etexilate (150 mg), a P-gp substrate, the C_max and AUC of dabigatran were increased but magnitude of this change differs depending on time between administration and the formulation of verapamil. Co-administration of verapamil 240 mg extended-release at the same time as dabigatran etexilate resulted in increased dabigatran exposure (increase of C_max by about 90% and AUC by about 70%).

Close clinical surveillance is recommended when verapamil is combined with dabigatran etexilate and particularly in the occurrence of bleeding, notably in patients having a mild to moderate renal impairment.

Other Cardiac therapy:

Concomitant use with ivabradine is contraindicated due to the additional heart rate lowering effect of verapamil to ivabradine (see section 4.3).

Other:

St. John’s Wort may reduce the plasma concentrations of verapamil, whereas grapefruit juice may increase the plasma concentrations of verapamil.

Although animal studies have not shown any teratogenic effects, verapamil should not be given during the first trimester of pregnancy unless, in the clinician’s judgement, it is essential for the welfare of the patient.

Verapamil hydrochloride is excreted in human breast milk. Limited human data from oral administration has shown that the infant relative dose of verapamil is low (0.1–1% of the mother’s oral dose) and that verapamil use may be compatible with breastfeeding. Due to the potential for serious adverse reactions in nursing infants, verapamil should only be used during lactation if it is essential for the welfare of the mother.

Depending on individual susceptibility, the patient’s ability to drive a vehicle, operate machinery or work under hazardous conditions may be impaired. This is particularly true in the initial stages of treatment, when changing over from another drug or when the dose is raised. Like many other common medicines, verapamil has been shown to increase the blood levels of alcohol and slow its elimination. Therefore, the effects of alcohol may be exaggerated.

Reactions from Postmarketing Surveillance or Phase IV Clinical Trials

The following adverse events reported with verapamil are listed below by system organ class:

Immune system disorders: allergic reactions (e.g. erythema, pruritus, urticaria) are very rarely seen.

Nervous system disorders: headache, dizziness, paresthesia, tremor and extrapyramidal syndrome.

Ear and labyrinth disorders: vertigo and tinnitus.

Cardiac disorders/vascular disorders: bradycardic arrhythmias such as sinus bradycardia, sinus arrest with asystole, 2^nd and 3^rd degree AV block, bradyarrhythmia in atrial fibrillation, peripheral oedema, palpitations, tachycardia, development or aggravation of heart failure and hypotension. There have been rare reports of flushing.

Gastrointestinal disorders: nausea, vomiting, constipation, ileus and abdominal pain/discomfort. Gingival hyperplasia may occur very rarely when the drug is administered over prolonged periods, and is fully reversible when the drug is discontinued.

Skin and subcutaneous tissue disorders: ankle oedema, Quincke’s oedema, Steven-Johnson syndrome, erythema multiforme, erythromelalgia, alopecia and purpura.

Musculoskeletal and connective tissue disorders: muscular weakness, myalgia and arthralgia.

Reproductive system and breast disorders: impotence (erectile dysfunction) has been rarely reported and isolated cases of galactorrhoea. On very rare occasions, gynaecomastia has been observed in elderly male patients under long-term verapamil treatment, and is fully reversible in all cases when the drug was discontinued.

General disorders and administration site conditions: fatigue.

Investigations: A reversible impairment of liver function characterized by an increase of transaminase and/or alkaline phosphatase may occur on very rare occasions during verapamil treatment and is most probably a hypersensitivity reaction. Rises in blood prolactin levels have been reported.

None stated.