High levels of adrenaline and noradrenaline have a protective effect on the cardiac electrophysiology because they bind to beta 2 adrenergic receptors, which, when activated, extracellularly decrease potassium concentration.Hyperkalemic periodic paralysis is an autosomal dominant clinical condition where there is a mutation in gene located at 17q23 that regulates the production of protein SCN4A. SCN4A is an important component of sodium channels in skeletal muscles. During exercise, sodium channels would open to allow influx of sodium into the muscle cells for depolarization to occur. But in hyperkalemic periodic paralysis, sodium channels are slow to close after exercise, causing excessive influx of sodium and displacement of potassium out of the cells.Rare causes of hyperkalemia are discussed as follows. Acute digitalis overdose such as digoxin toxicity may cause hyperkalemia through the inhibition of sodium-potassium-ATPase pump. Massive blood transfusion can cause hyperkalemia in infants due to leakage of potassium out of the red blood cells during storage. Giving succinylcholine to people with conditions such as burns, trauma, infection, prolonged immobilisation can cause hyperkalemia due to widespread activation of acetylcholine receptors rather than a specific group of muscles. Arginine hydrochloride is used to treat refractory metabolic alkalosis. The arginine ions can enter cells and displace potassium out of the cells, causing hyperkalemia. Calcineurin inhibitors such as cyclosporine, tacrolimus, diazoxide, and minoxidil can cause hyperkalemia. Box jellyfish venom can also cause hyperkalemia.
Oral use
The label for oral formulations of cysteamine carry warnings about symptoms similar to Ehlers-Danlos syndrome, severe skin rashes, ulcers or bleeding in the stomach and intestines, central nervous symptoms including  seizures, lethargy, somnolence, depression, and encephalopathy, low white blood cell levels, elevated alkaline phosphatase, and idiopathic intracranial hypertension that can cause  headache, tinnitus, dizziness, nausea, double or blurry vision, loss of vision, and pain behind the eye or pain with eye movement.The main side effects are Ehlers-Danlos syndrome, severe skin rashes, ulcers or bleeding in the stomach and intestines, central nervous symptoms, low white blood cell levels, elevated alkaline phosphatase, and idiopathic intracranial hypertension (IIH). IIH can cause headache, ringing in the ears, dizziness, nausea, blurry vision, loss of vision, and pain behind the eye or with eye movement.Additional adverse effects of oral cysteamine include bad breath, skin odor, vomiting, nausea, stomach pain, diarrhea, and loss of appetite.The drug is in pregnancy category C; the risks of cysteamine to a fetus are not known but it harms babies in animal models at doses less than those given to people.For eye drops, the most common adverse effects are  sensitivity to light, redness, and eye pain, headache, and visual field defects. Interactions
There are no drug interactions for normal capsules or eye drops, but the extended release capsules should not be taken with drugs that affect stomach acid like proton pump inhibitors or with alcohol, as they can cause the drug to be released too quickly. It doesnt inhibit any cytochrome P450 enzymes.