Table 1. Medications evaluated for the medical management of painful achalasia.

Drug class	Mechanism of action in achalasia	Common adverse effects 30
Calcium channel blockers3	Reduce intracellular uptake of calcium, hence decreasing muscle contractility, which relaxes the LOS	Headache, dizziness, flushing, peripheral oedema, nausea & vomiting, abdominal pain
Nitrates3	Cause the release of nitrous oxide, resulting in relaxation of the LOS	Headache, dizziness, flushing, drowsiness, nausea & vomiting, hypotension
Sildenafil21	Inhibits phosphodiesterase type 5, hence increasing cyclic monophosphate levels, which have an inhibitory effect on smooth muscle cells	Headache, dizziness, fluid retention, gastrointestinal symptoms including diarrhea, nausea, night sweats, anxiety, insomnia, cough
Terbutaline19	Stimulates beta2-receptors in smooth muscle cells which causes relaxation of the smooth muscle	Headache, nausea, arrythmias, palpitations, tremor, hypotension, hypokalaemia, muscle spasms

LOS, lower esophageal sphincter.