According to the sources provided, eteplirsen, which is marketed under the trade name Exondys 51, is primarily available in the United States. There is no specific information in the sources indicating that eteplirsen is available in other countries.

The first source, Drug Patent Watch, provides information about the patent status of drugs. It confirms that eteplirsen is only listed as being available in the United States [1].

The second source, the official website for Exondys 51, provides information about the drug, including its indications and usage. However, it does not mention availability in countries outside of the United States [2].

The third source is a scientific article that discusses the development and approval of eteplirsen. While it provides valuable insights into the drug's history and mechanism of action, it does not mention its availability in other countries [3].

In conclusion, based on the provided sources, it appears that eteplirsen is currently only available in the United States.

Sources:
[1] Drug Patent Watch. (n.d.). ETEPLIRSEN. Retrieved from https://www.drugpatentwatch.com/p/tradename/ETEPLIRSEN
[2] Exondys 51. (n.d.). Terms of Use. Retrieved from https://www.exondys51.com/terms
[3] Muntoni, F., Desguerre, I., Guglieri, M., Osorio, A. N., Kirschner, J., Tulinius, M., ... & Servais, L. (2018). Ataluren use in patients with nonsense mutation Duchenne muscular dystrophy: patient demographics and characteristics from the STRIDE Registry. Nucleic acid therapeutics, 28(3), 109-117. doi: 10.1089/nat.2018.0756.