Generally speaking companies &quot;extend&quot; their patent by making a slight tweak to get a new patent. But that doesn&#x27;t stop their old patent from expiring. And the old formula from becoming open to a generic.<p>So why aren&#x27;t there generic versions of old formulations? Who cares if it doesn&#x27;t have the latest tweak? The complain about such tweaks is that their minor and unimportant. Meaning the previous version should be just fine.