| Nabumetone; 6-methoxy-2-naphtaleneacetic acid | Pain | HPLC/FLR | 50-50000 ng/mL | Human EDTA Plasma |
| Naftidrofuryl | Cardiovascular | HPLC/FLR | 5-1000 ng/mL | Human EDTA Plasma |
| Naftifine | Infectious Disease | LC/MS/MS | 1-1000 ng/mL | Human Plasma |
| Naftifine | Infectious Disease | LC/MS/MS | 1-1000 ng/mL | Human Urine |
| Naloxone; 6-Beta-Hydroxy-Naloxol | Pain | LC/MS/MS | 5-500 pg/mL | Human Plasma |
| Naltrexone | Central Nervous System Agents | LC/MS/MS | 1-100 ng/mL | Human Plasma |
| Naltrexone; 6ß-naltrexol | Central Nervous System Agents | LC/MS/MS | 1-100 ng/mL | Human Plasma |
| Naproxen | Pain | HPLC/FLR | 1-100 µg/mL | Human EDTA Plasma |
| Naratriptan | Pain | LC/MS/MS | 50-25000 pg/mL | Human Plasma |
| Nateglinide | Endocrinology | LC/MS/MS | 50-20000 ng/mL | Human EDTA Plasma |
| Nebivolol | Cardiovascular | LC/MS/MS | 20-2500 pg/mL | Human EDTA Plasma |
| Nefazodone; Hydroxy Nefazodone and M-chlorophenylpiperazin | Central Nervous System Agents | LC/MS/MS | 2-500 ng/mL ; 0.4-100 ng/mL | Human EDTA Plasma |
| Nevirapine | Infectious Disease | LC/MS/MS | 30-3000 ng/mL | Human EDTA Plasma |
| Niacin | Cardiovascular | LC/MS/MS | 25-10000 ng/mL | Human EDTA Plasma |
| Niacin;Nicotinuric acid | Cardiovascular | LC/MS/MS | 25-10000 ng/mL for both | Human Plasma |
| Nicorandil | Cardiovascular | LC/MS/MS | 0.5-200 ng/mL | Human EDTA Plasma |
| Nicotine | Autonomic Drugs | LC/MS/MS | 1-100 ng/mL | Human Sodium Heparin Plasma |
| Nicotine metabolite: Cotinine | Autonomic Drugs | LC/MS/MS | 10-100 ng/mL | Human Plasma |
| Nifedipine | Cardiovascular | LC/MS/MS | 5-1000 ng/mL | Rat Plasma |
| Nifedipine | Cardiovascular | LC/MS/MS | 0.5-250 ng/mL | Human EDTA Plasma |
| Nifedipine | Cardiovascular | LC/MS/MS | 0.5-100 ng/mL | Human EDTA K2 Plasma |
| Nimesulide | Pain, Rheumatology | LC/MS | 50-10000 ng/mL | Human EDTA Plasma |
| Nitrofurantoin | TBD | LC/MS/MS | 1-1000 ng/mL | Human EDTA Plasma |
| Nizatidine and N-2-monodesmethylnizatidine | Gastrointestinal | HPLC/UV | 10-5000 ng/mL ; 5-2500 ng/mL | Human EDTA Plasma |
| Nomegestrol | Endocrinology | LC/MS/MS | 0.2-20 ng/mL | Human Plasma |
| Nomegestrol Acetate | Endocrinology | LC/MS/MS | 50-20000 pg/mL | Human EDTA Plasma |
| Norethindrone | Endocrinology | GC/MS/MS | 50-25000 pg/mL | Human Serum |
| Norethindrone | Endocrinology | LC/MS/MS | 100-50000 pg/mL | Human EDTA Plasma |
| Norgestimate; 17-deacetyl norgestimate and Levonorgestrel | Endocrinology | LC/MS/MS | 100-5000 ng/mL; 50-3000 pg/mL | Human EDTA Plasma |
| Nortriptyline; E-10-hydroxy nortriptyline | Central Nervous System Agents | LC/MS/MS | 1-200 ng/mL | Human EDTA Plasma |