This is the text extract for Clinical advice for switching diltiazem patients, browse documents here.

Dear Health Professional Changes to the available preparations of diltiazem hydrochloride As a result of concerns about diltiazem hydrochloride prescribing and dispensing errors, some preparations will be delisted from the Pharmaceutical Schedule from 1 June 2009 as follows:

Preparations that will be delisted Dilzem SR 90 mg and 120 mg (twice daily) sustained release capsules Dilzem LA 180 mg and 240 mg long-acting tablets Preparations that will remain available Dilzem 30 mg and 60 mg immediate release tablets Cardizem CD 120 mg, 180 mg and 240 mg long-acting capsules

Switching Current Patients The delisting of Dilzem SR (sustained release) and Dilzem LA (long-acting) will require current patients to be switched to another presentation. We suggest the following:

Currently taking Dilzem SR 90 mg capsule (twice daily) Dilzem SR 120 mg capsule (twice daily) Dilzem LA 180 mg tablet (once daily) Dilzem LA 240 mg tablet (once daily) Suggested new presentation Cardizem CD 180 mg capsule (once daily) Cardizem CD 240 mg capsule (once daily) Cardizem CD 180 mg capsule (once daily) Cardizem CD 240 mg capsule (once daily)

Titration to a higher or lower dose may be necessary and should be initiated as clinically warranted.

For patients taking Dilzem SR 90 mg or 120 mg once daily (even if it is not the recommended dosing regimen as the blood levels are not maintained above the minimum therapeutic level for 24 hours), we suggest the following:

Currently taking Dilzem SR 90 mg capsule (once daily) Dilzem SR 120 mg capsule (once daily) Suggested new presentation Cardizem CD 120 mg capsule (once daily) Cardizem CD 120 mg capsule (once daily)

These patients may be more likely to experience a change in effect therefore they should be monitored for adverse effects following the change.

The following pages contain additional information that may be of some assistance. Yours sincerely

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Dr Peter Moodie, Medical Director New Patients We suggest that new patients are initiated on a long-acting capsules (Cardizem CD 120 mg, 180 mg, or 240 mg). Where there are concerns that the patient may not be able to tolerate diltiazem, treatment could be initiated with an immediate release tablet (Dilzem 30 mg or 60 mg) and then the patient could be switched to a long-acting capsule once tolerability is established. When switching patients you should: Be aware of the peak concentration and duration of action of the different preparations:

Brandname Dilzem Dilzem SR Dilzem LA Cardizem CD Strengths 30 mg, 60 mg 90 mg, 120 mg 180 mg, 240 mg 120 mg, 180 mg, 240 mg Presentation Immediate release tablet Sustained release capsule Long-acting tablet Long-acting capsule Peak Concentration 2 to 4 hours 2 to 8 hours 2 to 8 hours 10 to 14 hours (based on CD 360 mg dose) Duration of Action Approximately 8 hours Approximately 16 hours Approximately 24 hours Approximately 24 hours

Consider the dosing and indication:

Brand name Dilzem 30 mg and 60 mg tablet Dilzem SR 90 mg and 120 mg capsule Dosage Angina: Initially 30 mg three to four times daily increasing to 240 mg daily in divided doses. The maximum recommended dose is 360 mg daily Angina, Adults: Initially 120 mg twice daily increasing if necessary to maximum of 2x90 mg twice daily Hypertension, Adults: 90 mg to a maximum of 360 mg daily or as recommended by the physician. Elderly: Initially 120 mg once daily increasing, if necessary, to 90 mg or 120 mg twice daily, or as recommended by the physician. Note: SR capsules are not to be prescribed as a once daily dosage for hypertension or angina (except when initiating treatment for hypertension) because blood levels are not maintained above the minimum therapeutic level for 24 hours. Cardizem CD 120 mg, 180 mg and 240 mg capsule Angina: Starting dose is 120 or 180 mg once daily. The dosage should be adjusted as required with patients responding to higher doses up to 360 mg once daily. When necessary titration may be carried out over a 7 to 14 day period. Hypertension: When used as monotherapy starting dose is 180 to 240 mg once daily, although some patients respond to lower doses. Usual dosage is 240 to 360 mg daily. Dosage should be adjusted as required. Maximum antihypertensive effect is usually observed by 14 days of chronic therapy therefore dosage adjustments should be scheduled accordingly. Angina: Initially 120 mg once daily up to a maximum of 360 mg once daily. Hypertension: Initially between 180-240 mg once daily or as clinically warranted to a maximum of 360 mg per day.

Dilzem LA 180 mg and 240 mg tablet

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Consider the timing of the next dose. A patient taking Dilzem SR or LA can switch to Cardizem CD directly. For example, a patient on Dilzem SR capsule twice daily can take the last capsule at night and then start on Cardizem CD the next morning. Consider measuring the patient’s blood pressure two weeks after the change. Cardizem CD has a different release profile to Dilzem SR and LA and therefore there may be changes in a patient’s blood pressure control. You may wish to consider measuring the patient’s blood pressure two weeks after a switch to Cardizem CD and adjust the dose as necessary. Educate patients about dosing instructions. When switching patients to Cardizem CD ensure that the patient understands that this is a once daily product, particularly if they were previously on a twice daily product. Educate patients about the reason for the switch. Patients are much more likely to be willing to try a new treatment if they understand the reason for the change. Explain to the patient that the change is to avoid confusion between the brands and therefore reduce the risk of prescribing and dispensing errors. Monitor some populations closely. For most patients the change will be uneventful, however some patients may be more susceptible to adverse effects. The elderly should be monitored for changes in blood pressure. If blood pressure is uncontrolled before or after the change, changes to other medications and/or specialist review may be required. Be aware that switching patients to an alternative can unexpectedly result in tolerability issues for some patients. The different release profile of Cardizem CD compared with Dilzem SR or LA may cause slight changes in blood pressure control. Another possible but unlikely problem is hypersensitivity reactions due to different excipients. Monitoring for these adverse reactions is recommended. Be aware of alternatives should a patient not tolerate Cardizem CD. If a patient cannot tolerate Cardizem CD then there are a number of alternatives. Other calcium channel blockers are available; Verapamil or the dihydropyridine calcium channel blockers such as amlodipine, felodipine, isradipine, and nifedipine. However, these are different classes of calcium channel blocker and would have to be initiated from starting doses. Another option is to use another antihypertensive agent such as a thiazide, ACE inhibitor, angiotensin receptor blocker, or a beta blocker. See BPJ6 for information about the treatment of high blood pressure. More Information If you have any queries about these changes please contact the PHARMAC helpline on 0800 66 00 50 (9 am to 5 pm weekdays).

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