Charak Samhita
कदाचिच्छ्लेष्मणा रुद्धं तिष्ठत्युरसि भेषजम्। क्षीणे श्लेष्मणि सायाह्ने रात्रौ वा तत्प्रवर्तते॥७४॥
There may be possibilities of virechana drugs obstructed in the chest region (stomach) because of kapha, then elimination starts in the evening or night after the reduction of kapha.
english translation
कदाचिच्छ्लेष्मणा रुद्धं तिष्ठत्युरसि भेषजम्। क्षीणे श्लेष्मणि सायाह्ने रात्रौ वा तत्प्रवर्तते॥७४॥
There may be possibilities of virechana drugs obstructed in the chest region (stomach) because of kapha, then elimination starts in the evening or night after the reduction of kapha.
english translation