Pill assortment. Close-up of an assortment of pills. The red pills contain the tricyclic anti- depressant Dothiepin. The blue and yellow pills both contain Diazepam (Valium). The yellow pills contain 5 milligrams (mg), and the blue contain 10mg. The pink pills contain the beta-blocker drug Propranolol. Dothiepin is a sedative antidepressant, used mainly to treat agitated or anxious depressives. It has numerous side-effects, and newer drugs are now preferred in many cases. Propranolol is a heart drug used to treat arrhythmias, hypertension (high blood pressure) and angina pectoris. Valium is a tranquillizer used to treat anxiety, convulsions and insomnia.