Macbeth and The Laboratory are related via the theme of power in that both stories concern a murder plot. The murder is intended to gain the murderer some power they covet, which is currently possessed by their intended victim; Macbeth seeks the crown of Scotland via murder of the king, and the narratrix of The Laboratory seeks a redress of grievances via the murder of her rival.
Both characters use murder to obtain power, and power is what drove them to conceive of the murders. Thus power is portrayed as a corrupting influence, even before it is obtained. It is also seen as transferrable and embodied; power may be acquired by killing the current holder and taking it from them. Macbeth later realizes that this attitude would just as likely result in his own murder in the future.
Both stories also involve women who will do anything to obtain the power they seek; Lady Macbeth attests to murdering children if it will gain her a throne, and the narratrix states that her fortune, "all her jewels", and a kiss, if the apothecary wants it, are a small price to see her rival dead. These behaviors stand in contrast to the theme of women as mothers (Lady Macbeth specifically calls for her milk to turn to poison); these are very anti-motherly actions, and it can be implied that power can turn a woman away from her "purpose".