Drug/Small Molecule:

hydrocodone

Narcotic analgesic related to codeine, but more potent and more addicting by weight. It is used also as cough suppressant. PubChem (source: Drug Bank)

For relief of moderate to moderately severe pain. (source: Drug Bank)

Hydrocodone acts as a weak agonist at OP1, OP2, and OP3 opiate receptors within the central nervous system (CNS). Hydrocodone primarily affects OP3 receptors, which are coupled with G-protein receptors and function as modulators, both positive and negative, of synaptic transmission via G-proteins that activate effector proteins. Binding of the opiate stimulates the exchange of GTP for GDP on the G-protein complex. As the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane, opioids decrease intracellular cAMP by inhibiting adenylate cyclase. Subsequently, the release of nociceptive neurotransmitters such as substance P, GABA, dopamine, acetylcholine, and noradrenaline is inhibited. Opioids such as hydrocodone also inhibit the release of vasopressin, somatostatin, insulin, and glucagon. Opioids close N-type voltage-operated calcium channels (OP2-receptor agonist) and open calcium-dependent inwardly rectifying potassium channels (OP3 and OP1 receptor agonist). This results in hyperpolarization and reduced neuronal excitability. (source: Drug Bank)

Hydrocodone, a semisynthetic opiate agonist and hydrogenated ketone derivative, is similar to other phenanthrene derivatives, such as codeine. Used as an analgesic, hydrocodone is combined with acetaminophen, ibuprofen, or aspirin to treat pain. Used as an antitussive, hydrocodone is combined with phenylephrine, pseudoephedrine, phenylpropanolamine, guaifenesin, pyrilamine, pheniramine, or chlorpheniramine. (source: Drug Bank)

Avoid alcohol.
Take with food.
To avoid constipation: increase your daily intake of fiber (beans, whole grains, vegetables). (source: Drug Bank)

Hepatic and also in intestinal mucosa. (source: Drug Bank)

As most agents in the 5-ring morphinan group of semi-synthetic opioids bind plasma protein to a similar degree (range 19% hydromorphone to 45% oxycodone), hydrocodone is expected to fall within this range. (source: Drug Bank)

Well absorbed from the gastrointestinal tract. (source: Drug Bank)

Symptoms of overdose include respiratory depression (a decrease in respiratory rate and/or tidal volume, Cheyne-Stokes respiration, cyanosis), extreme somnolence progressing to stupor or coma, skeletal muscle flaccidity, dizziness, ringing in the ears, confusion, blurred vision, eye problems, cold and clammy skin, and sometimes bradycardia and hypotension. In severe overdose, apnea, circulatory collapse, cardiac arrest and death may occur. LD₅₀=85.7mg/kg (subcutaneous, in mice). (source: Drug Bank)

CN1CC[C@]23c4c5ccc(c4O[C@H]2C(=O)CC[C@H]3[C@H]1C5)OC (source: Drug Bank)