Here’s the quick explanation of what is going on here. PPI’s once absorbed are metabolized into an “inactive form” by an enzyme in the liver. Clopidogrel on the other hand once absorbed is metabolized to an “activated form” by the same enzyme in the liver.
When you have both medications in your system at the same time they compete for that enzyme. As a result they will not be metabolized as quickly and therefor PPI’s will not be inactivated as quickly ( resulting in higher levels of the active form) and Clopidogrel will not be activated as quickly resulting in less of the active form.
In most cases this difference in levels of active drug will not be clinically significant but you need to talk to your husbands doctor since there are alternatives he can use if his doctor feels the dose is crucial.