Compounding pharmacy Imprimis Pharmaceuticals Inc said, it plans to make a cheaper alternative to Retrophin Inc's kidney stone drug, Thiola.

Retrophin, under former Chief Executive Martin Shkreli, raised the price of the drug from $1.50 to $30 per tablet after buying the rights from Mission Pharmacal Co in 2014, Imprimis said.

After Shkreli's departure, the price of Thiola still remains high, Imprimis said.

The drug treats cystinuria, an inherited disease that causes stones made of the amino acid, cystine, in the kidneys, bladder or urethra.

Imprimis said its compounded alternative may reduce the cost of the drug by more than 70 percent and will be available to patients in April.

The company also makes a $1 copycat of Turing Pharmaceuticals' anti-infective drug, Daraprim, whose price was raised from $13.50 to $750 per pill by Shkreli's in a controversial move.

Imprimis had said it sees an opportunity to build a market in countering massive drug price hikes.

Unlike Thiola, Imprimis's formulation in itself is not FDA approved, and can only be used when prescribed by a doctor for a particular patient.

Compounded therapies are not subjected to the same level of safety and efficacy evaluation and may not offer the same therapeutic outcome for patients, Retrophin said in a separate statement.