| Hyaluronic acid Drug Metabolism |  | Metabolic | Hyaluronic acid |
| Hydrochlorothiazide Action Pathway |  | Drug Action | Cysteine / Hydrochlorothiazide / Potassium cation / Urea |
| Hydrochlorothiazide Diuretic Action Pathway |  | Drug Action | Hydrochlorothiazide / Potassium cation / Calcium |
| Hydrochlorothiazide Drug Metabolism |  | Metabolic | Hydrochlorothiazide |
| Hydrocodone Action Pathway |  | Drug Action | ATP / Norepinephrine / Hydrocodone / Dopamine / Potassium cation / Calcium |
| Hydrocodone Opioid Agonist Action Pathway |  | Drug Action | ATP / Hydrocodone / Calcium / Magnesium cation / Cyclic adenosine monophosphate / gamma-Aminobutyric acid / Pyrophosphoric acid / Sar9, Met (O2)11-Substance P |
| Hydrocortamate Action Pathway |  | Drug Action | Glutathione / Hydrocortamate / Dinoprostone / Calcium / Prostaglandin D2 / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Hydrocortamate Predicted Metabolism Pathway |  | Metabolic | Hydrocortamate / Mesoheme |
| Hydrocortisone Action Pathway |  | Drug Action | Glutathione / Hydrocortisone / Dinoprostone / Calcium / Prostaglandin D2 / Mesoheme / Prostaglandin G2 / 1-Methylhistidine / Arachidonic Acid |
| Hydroflumethiazide Action Pathway |  | Drug Action | Cysteine / Hydroflumethiazide / Potassium cation / Urea |
| Hydroflumethiazide Diuretic Action Pathway |  | Drug Action | Hydroflumethiazide / Potassium cation / Calcium |
| Hydroflumethiazide Drug Metabolism |  | Metabolic | Hydroflumethiazide |
| Hydromorphone Action Pathway |  | Drug Action | ATP / Hydromorphone / Norepinephrine / Dopamine / Potassium cation / Calcium |
| Hydromorphone Opioid Agonist Action Pathway |  | Drug Action | ATP / Hydromorphone / Calcium / Magnesium cation / Cyclic adenosine monophosphate / gamma-Aminobutyric acid / Pyrophosphoric acid / Sar9, Met (O2)11-Substance P |
| Hydrotalcite Drug Metabolism |  | Metabolic | Hydrotalcite |
| Hydroxyethyl cellulose Drug Metabolism |  | Metabolic | Hydroxyethyl cellulose |
| Hydroxyethylpromethazine H1-Antihistamine Action |  | Drug Action | Calcium / Hydroxyethylpromethazine |
| Hydroxyurea Drug Metabolism |  | Metabolic | Hydroxyurea |
| Hydroxyzine H1 Antihistamine Neurological Sleep Action Pathway |  | Drug Action | Pyridoxal phosphate / Histidine / Hydroxyzine / Calcium |
| Hydroxyzine H1 Antihistamine Smooth Muscle Relaxation Action Pathway |  | Drug Action | Hydroxyzine / Calcium / Magnesium cation |
| Hydroxyzine H1-Antihistamine Action |  | Drug Action | Hydroxyzine / Calcium |
| Hydroxyzine H1-Antihistamine Blood Vessel Constriction Action Pathway |  | Drug Action | Arginine / Citrulline / Sapropterin / Nitric Oxide / Hydroxyzine / Calcium / Magnesium cation / Mesoheme / Flavin adenine dinucleotide / Flavin mononucleotide |
| Hydroxyzine H1-Antihistamine Immune Response Action Pathway |  | Drug Action | Hydroxyzine / Calcium |
| Hyoscyamine M2 Smooth Muscle Relaxation Action Pathway |  | Drug Action | ATP / Hyoscyamine / Potassium cation / Calcium / Magnesium cation / Cyclic adenosine monophosphate |
| Hyper-IgD Syndrome |  | Disease | Cholecalciferol / ATP / Magnesium cation / Iron / Dimethylallyl Diphosphate / Formic acid / Geranyl Diphosphate / Mesoheme / Flavin adenine dinucleotide / Palmitic Acid / Pyrophosphoric acid / Cholesterol / ISOPENTENYL PYROPHOSPHATE / Farnesyl diphosphate |