Compositions comprising alternating 2′-modified nucleosides for use in gene modulation

A composition comprising a first oligomeric compound and a second oligomeric compound, wherein:

• said first oligomeric compound is capable of hybridizing with said second oligomeric compound;
• said first oligomeric compound is complementary to and capable of hybridizing to a selected nucleic acid target;
• each of said first and said second oligomeric compounds independently comprises 20-23 linked nucleosides;
• at least one of said first and said second oligomeric compounds comprises a region having the formula X1-Y-X2, wherein Y is a region of from about 5 to about 12 linked nucleosides and each of X1 and X2 is, independently, a plurality of linked nucleosides having the formula FSFS, where one of F and S is a 2′-F modified nucleoside and the other of F and S is a 2′-O-CH3 modified nucleoside;
• and
• each internucleoside linkage of said first and said second oligomeric compound is, independently, a phosphodiester or a phosphorothioate internucleoside linkage.