The present application relates to internally cyclized naphthamide compounds of the formula Ia (wherein R.sup.1a, R.sup.1b, R.sup.1c, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, X.sup.1, X.sup.2, Y, Z, and n are as defined herein), which are useful, for example, for antagonizing the pharmacological actions of the neurokinin 1 (NK.sub.1) receptor. In particular, these compounds are useful in the treatment of diseases in which Substance P is involved such as, for example, major depressive disorder, severe anxiety disorders, stress disorders, major depressive disorder with anxiety, eating disorders, bipolar disorder, substance use disorder, schizophrenic disorders, psychotic disorders, movement disorders, cognitive disorders, depression and/or anxiety, mania or hypomania, aggressive behaviour, obesity, rheumatoid arthritis, Alzheimer's disease, cancer, oedema, allergic rhinitis, inflammation, pain, gastrointestinal-hypermotility, Huntington's disease, chronic obstructive pulmonary disorder (COPD), hypertension, migraine, bladder hypermotility, and urticaria.