Protoveratrine A, the principal alkaloid of Veratrum album, has been used in the treatment of hypertension but has largely been replaced by drugs with fewer adverse effects.

Phensuximide is an anticonvulsant in the succinimide class. For the treatment of epilepsy. Phensuximide suppresses the paroxysmal three cycle per second spike and wave EEG pattern associated with lapses of consciousness in absence (petit mal) seizures. The frequency of attacks is reduced by depression of nerve transmission in the motor cortex. Phensuximide's mechanism of action not understood, but may act in inhibitory neuronal systems that are important in the generation of the three per second rhythm. It's effects may be related to its ability to inhibit depolarization-induced accumulation of cyclic AMP and cyclic GMP in brain tissue.

Sulfamethizole is an oral antiobiotic, which was used against urinary tract infections under the name Thiosulfil. Sulfamethizole blocks bacterial growth by inhibiting folic acid synthesis via enzyme called dihydropteroate synthase. The drug is no longer marketed in the USA.

Propoxycaine hydrochloride is a local anesthetic of the ester type that has a rapid onset of action and a longer duration of action than procaine hydrochloride. Propoxycaine Hydrochloride is the hydrochloride salt form of propoxycaine, a para-aminobenzoic acid ester. Propoxycaine binds to and inhibits voltage-gated sodium channels, thereby inhibiting the ionic flux required for the initiation and conduction of impulses. This results in a loss of sensation.

Phenylbutazone is an anti-inflammatory drug, which binds to and inactivates cyclooxygenases and prostacyclin synthase through peroxide (H2O2) mediated deactivation. The reduced production of prostaglandin leads to reduced inflammation of the surrounding tissues. Phenylbutazone was marked under the brand name butazolidin for the treatment rheumatoid arthritis and gout, but then this usage was discontinued. In addition, phenylbutazone is used in UK for the treatment of ankylosing spondylitis, but only in those cases, when other therapies are unsuitable.

Phenindione is an anticoagulant which functions as a Vitamin K antagonist. The drug was discontinued in USA, but still in use worldwide.

Gallamine triethiodide is a synthetic nondepolarizing blocking drug, which is allosteric antagonist of muscarinic M2 acetylcholine receptor and inhibitor of acetylcholinesterase. It was used under brand name flaxedil to stabilize muscle contractions during surgical procedures. However, this usage was discontinued. It was shown, that gallamine caused tachycardia by depressing the vagus nerve and, occasionally, hypertension and increased cardiac output.

Dyphylline is 7-(2,3-dihydroxypropyl)-theophylline, a white, extremely bitter, amorphous powder that is freely soluble in water and soluble in alcohol. Dyphylline is stable in gastrointestinal fluids over a wide range of pH. Dyphylline is a xanthine derivative with pharmacologic actions similar to theophylline and other members of this class of drugs. Its primary action is that of bronchodilation, but it also exhibits peripheral vasodilatory and other smooth muscle relaxant activity to a lesser degree. The bronchodilatory action of dyphylline, as with other xanthines, is thought to be mediated through competitive inhibition of phosphodiesterase with a resulting increase in cyclic AMP producing relaxation of the bronchial smooth muscle. Dyphylline exerts its bronchodilatory effects directly and, unlike theophylline, is excreted unchanged by the kidneys without being metabolized by the liver. Because of this, dyphylline pharmacokinetics and plasma levels are not influenced by various factors that affect liver function and hepatic enzyme activity, such as smoking, age, congestive heart failure, or concomitant use of drugs which affect liver function.

Dihydro-alpha-ergocryptine is an ergot alkaloid that has an agonist activity on D2 dopaminergic receptors and a partial agonist activity on D1 receptors. It also demonstrated antagonistic activity towards alpha-adrenergic receptors. The drug was approved by FDA in combination with other alkaloids (dihydroergocornine, dihydroergocristine and dihydro-beta-ergocryptine mesylate salts) under the name Hydergine for the treatment of dimentia and cerebrovascular insufficiency.

Hexamethonium is a nicotinic cholinergic antagonist. It was used to treat hypertension, but has never been approved and was discontinued because of the non-specified treatment. When this drug tried to use in medical study via inhalation, one of the volunteer died, the death has been described as “particularly disturbing ”because it was a healthy volunteer who had no thing to gain by taking part in the study. This volunteer participated in a study designed to provoke a mild asthma attack in order to help doctors discover the reflex that protects the lungs of healthy people against asthma attacks. Hexamethonium is poorly absorbed from the gastrointestinal tract and does not cross the blood-brain barrier. Now it is widely used a research tool.