private void cboLoadDrug_SelectedIndexChanged(object sender, EventArgs e)
 {
     // selectClass.SelectDrug(textBox5.Text.Trim());
     selectClass.SelectDrug(cboLoadDrug.SelectedItem.ToString());
     textBox6.Text = selectClass.DrugPrice.ToString();
     selectClass.selectDrugQty(cboLoadDrug.SelectedItem.ToString());
     getQty.Text = selectClass.drugQty.ToString();
 }