Brief Answer:
The above medicines should not be taken together unless recommended

Detailed Answer:
Hi XXXX,
Thanks for writing in to us.

I have read through your query in detail.
Please find my observations below.

1. Benazepril is an angiotensin-converting enzyme (ACE) inhibitor and given to treat high blood pressure.

2. Amlodipine is a calcium channel blocker and reduces high blood pressure and coronary heart disease.

3. Diltiazem is a calcium channel blocker and an inhibitor of the cytochrome P-450 3A4 enzyme system. It used to treat high blood pressure and heart rhythm disorder.

Following interactions are known to occur when the above medicines are taken together.

(i) Diltiazem might increase the plasma concentrations of amlodipine and this might require dose adjustment of amlodipine. This combination is to be given with care.

(ii) Diltiazem and benazepril might cause additive effects and this requires careful monitoring during first 3 weeks after initiating treatment.

(iii) Amlodipine and benazepril might also have additive effects and require close monitoring if taken together for the first three weeks following starting treatment.

Hope this answers your question. Please feel free to correct any oversight in my interpretation of your problems and discuss them in detail as per your requirements.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek

---