It is very difficult to determine how long a case can take to settle and depends on many factors. In some circumstances a claim can settle before a lawsuit is filed. In other circumstances, the case can go to trial and then appealed. Instead of focusing on how long it will take to settle, you should determine whether malpractice actually occurred. The fact that the prescription was double the strength alone is not necessarily malpractice. Did the pharmacy give a different prescription than what the doctor wrote? Did the doctor write the prescription with double strength? Was giving your mother a double strength prescription below the standard of care? You should get a copy of your mother's medical records and consult an attorney.
Impossible to know the answer to this question. The best advice I can give you is to consult with a personal injury lawyer in your area.
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