Drugs can come from natural sources like plants, animals, and microorganisms, or they can be produced synthetically through cell culture, recombinant DNA technology, or monoclonal antibodies. Drugs are formulated into solid dosage forms like tablets and capsules, semisolid forms like ointments and creams, or liquid forms like solutions, suspensions, and emulsions. The active drug ingredient is combined with excipients like diluents, binders, disintegrants, lubricants, colorants, flavors, and sweetening agents to aid delivery and administration of the drug. Gaseous drugs can also be delivered as aerosols, gases, or volatile liquids.