The present invention encompasses Pregabalin substantially free of Lactam and a process for obtaining Pregabalin substantially free of Lactam comprising extracting an acidic mixture containing a complex of Pregabalin with a strong mineral acid, with C3-8 alcohol; and combining the organic phase with an organic base. A stent assembly of the invention generally comprises a stent having cover connectors in contact with a cover to secure the cover to a surface of the stent. When a first part of a tapered portion of the valve member opposes to the monitoring portion, a first contact part of each of the guide portions may contact the monitoring portion.