HDMP-28 or methylnaphthidate is a piperidine based stimulant drug, closely related to methylphenidate, but with the phenyl ring replaced by naphthalene. It is a potent dopamine reuptake inhibitor, with several times the potency of methylphenidate and a short duration of action, and is a structural isomer of another potent dopamine reuptake inhibitor, N,O-Dimethyl-4-(2-naphthyl)piperidine-3-carboxylate.

Most of the TMP analogs of HDMP-28 have SERT Ki values in the range >10,000 and so are selective for dopamine and noradrenaline reuptake, with little or no effect on serotonin. HDMP-28 also has high affinity to SERT, and so behaves as a triple reuptake inhibitor.

D.R. = Discrimination Ratio = [3H]DA ÷ [3H]CFT.

A low D.R. = addictive, whereas a high D.R. = low propensity for self-administration.

David Stefan "Bud" Norris (March 2, 1985 in Greenbrae, California) is a Major League Baseball starting pitcher for the Houston Astros.

From Cal Poly, Norris was selected by the Houston Astros in the sixth round (189th overall) of the 2006 amateur entry draft. In 2009, Norris received an invitation to the Astros' spring training camp.Baseball America ranked him as the number two prospect in the Astros' system. In August 2009, he was named the Pacific Coast League Pitcher of the Year after leading the league with a 2.63 Earned Run Average.

In July 2009, Norris was called up to pitch for the Astros following an injury to starting pitcher Roy Oswalt. He made his Major League debut on July 29. In his first Major League start, he pitched 7 shut-out innings against the St. Louis Cardinals on August 2, 2009 to earn his first career victory. He took a no-hitter into the sixth inning. In his rookie season overall, Norris went 6-3 in ten starts for a 4.53 Earned Run Average. He was shut down near the end of the season to prevent potential injury. He had shaky start in 2010, having a 5.97 ERA and a 2-6 record up to the allstar break 2010; After the allstar break he was 'lights out,' performing at 7-4. He finished the year at 9-10 with a 4.92 ERA. He is currently at 21-24 with a 4.33 ERA for his Major League career. In 2011, Norris win-loss record stood at 6-11 even though he actually pitched quite well, as evidenced by his 3.77 ERA. Houston's terrible offense in 2011 resulted in many low scoring losses. On June 8, he had a no-hitter going until, in the seventh inning, Lance Berkman broke it up with his 14th home run of the season and his fourth against Houston of the season. He still was able to earn the win.