According to [http://www.ebi.ac.uk/citexplore/ CiteXplore], [http://www.ebi.ac.uk/citexplore/performQuery.do?queryString=cites:{{{pmid|}}}_MED this reference] has {{#show: {{PAGENAME}} |? Number of citations}} [http://www.ebi.ac.uk/citexplore/performQuery.do?queryString=cites:{{{pmid|}}}_MED citations].

<small><br/>For reference, you can check Google Scholar, which lacks an API because Google are evil.</small>