Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers, 2nd edition, has an excellent section on citing patents. Very detailed.
MLA Manual of Style is silent on the issue of patents. Using their recommendations for citing government documents with a names author, the following style is suggested. If you need to cite a patent for you class using the MLA style, please speak with your professor to determine what is appropriate for your class.
Inventor/author. Name of Patent. Labeled Patent or Application Number. Patent Office. Issue Date.
Foerch, Renate, et al. Modification of Polymer Surfaces by Two-Step Reactions. United States Patent US 5,147,678. United States Patent and Trademark Office. 15 Sept. 1992.
Patents are listed using the author's last name and should include both filing date and issue date when known.
Author's last name, author's first name. Year of patent. Name of patent. Country of patent. Patent number, filed (month date, year), and issued (month date, year).
APA style for citing patents is straightforward.
Inventor/author. (date). Labeled Patent or Application Number. Place. Office.
Some examples with the patent title included (title not required by APA).
Williams, D. (2005). Screw less clip mount computer drive. U.S. Patent No. 6,885,550. Washington, DC: U.S. Patent and Trademark Office.
Cameron B, Crouzet J. (2006). Cells with altered betaine catabolism, their preparation and their use, in particular for producing metabolites or enzymes. European patent No. 0673422 B1. Munich, Germany. European Patent Office.
Clark, J. R., Moore, J. M. (2007). Peach tree - named 'White County' cultivar. U.S. Plant Patent Application No. 17742 (P3). Washington, DC: U.S. Patent and Trademark Office.
Julien, G. S. (2002). Cutting instruments. U.S. Patent Application No. 2002083598(A1). Washington, DC: U.S. Patent and Trademark Office.
The Publications Manual of the American Psychological Association, commonly referred to as the APA Style Guide, provides one example of a US Patent and is silent on how patent applications and patents from other countries should be cited.
The information required in the APA style for patents is the minimum required to locate the patent if there are NO errors in the citation. Though the patent name can change, this librarian recommends including the name of the patent after the date and before the labeled patent/patent application number as most scientific styles recommend. Including the patent name allows the reader to determine if the patent is of sufficient interest to pursue and, if there has been changes in the patent number (or kind code), verify they have the patent of interest.
If you need to cite a patent for you class using the APA style, please speak with your professor to determine what is appropriate for your class.