Appellant was indicted for the offense of driving while having 0.12 percent by weight of alcohol in his blood. OCGA 40-6-391 (a) (4). He was tried before a jury and found guilty. Appellant appeals from the denial of his motion for new trial.

1. Appellant enumerates the general grounds. Evidence in the form of the results of an intoximeter test authorized a finding that appellant had 0.12 percent by weight of alcohol in his blood. Appellant nonetheless contends that his conviction cannot stand, relying upon the State's failure to rebut the following defensive contention: Prior to the time of his arrest, he had been taking a prescription drug, the major component of which was alcohol. However, OCGA 40-6-391(b) specifically provides: "The fact that any person charged with violating this Code section is or has been legally entitled to use a drug shall not constitute a defense against any charge of violating this Code section." After a careful review of the entire record, we find that a rational trior of fact could reasonably have found from the evidence adduced at trial proof of appellant's guilt beyond a reasonable doubt. Jackson v. Virginia, 443 U. S. 307 (99 SC 2781, 61 LE2d 560) (1979).

3. Error, if any, in the admission of documentary evidence regarding appellant's original refusal to submit to the intoximeter test was harmless. That documentary evidence was merely cumulative of oral testimony to the same effect. See generally Bishop v. State, 155 Ga. App. 611, 614 (2c) (271 SE2d 743) (1980).